Adenine Phosphoribosyltransferase Deficiency (APRT),Disease

Adenine phosphoribosyltransferase (APRT) deficiency is an inherited condition that affects the kidneys and urinary tract. The most common feature of this condition is recurrent kidney stones; urinary tract stones are also a frequent symptom. Kidney and urinary tract stones can create blockages in the urinary tract, causing pain during urination and difficulty releasing urine.


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Mitochondrial DNA Depletion Syndrome,Disease

Mitochondrial DNA depletion syndromes are a group of autosomal recessive disorders. They are characterized by decreased levels of mitochondrial DNA (mtDNA), resulting in decreased energy production. Mitochondrial DNA depletion syndrome-3 is caused by a mutation in the gene coding for deoxyguanosine kinase (DGUOK). DGUOK aids in maintaining the levels of available deoxyguanosine triphosphate (dGTP), thus the deficiency of DGUOK impairs the synthesis of dGTP. Symptoms of DGUOK deficiency can arise in the form of a multi-system disease in neonates or an isolated hepatic disease in infancy, with the former being more common. The most common cause of death in both forms is progressive hepative disease.


Adenosine monophosphate (AMP) deaminase deficiency is a condition that can affect the muscles used for movement (skeletal muscles). People with this condition do not make enough of an enzyme called AMP deaminase. In most people, AMP deaminase deficiency does not cause any symptoms. People who do experience symptoms typically have muscle pain (myalgia) or weakness after exercise or prolonged physical activity. They often get tired more quickly and stay tired longer than would normally be expected. Some affected individuals have more severe symptoms, but it is unclear whether these symptoms are due solely to a lack of AMP deaminase or additional factors. Muscle weakness is typically apparent beginning in childhood or early adulthood. Researchers have proposed three types of AMP deaminase deficiency, which are distinguished by their symptoms and genetic cause.


Carnitine Palmitoyl Transferase Deficiency I,Disease

Carnitine palmitoyltransferase I (CPT I) deficiency is a condition that prevents the body from using certain fats for energy, particularly during periods without food (fasting). The severity of this condition varies among affected individuals. Signs and symptoms of CPT I deficiency often appear during early childhood. Affected individuals usually have low blood sugar (hypoglycemia) and a low level of ketones, which are produced during the breakdown of fats and used for energy. Together these signs are called hypoketotic hypoglycemia. People with CPT I deficiency can also have an enlarged liver (hepatomegaly), liver malfunction, and elevated levels of carnitine in the blood. Carnitine, a natural substance acquired mostly through the diet, is used by cells to process fats and produce energy. Individuals with CPT I deficiency are at risk for nervous system damage, liver failure, seizures, coma, and sudden death. Mutations in the CPT1A gene cause CPT I deficiency.


Long Chain Acyl-CoA Dehydrogenase Deficiency (LCAD),Disease

Very Long Chain Acyl CoA Dehydrogenase Deficiency (VLCADD) is a rare disorder that is inherited through an autosomal recessive trait, and prevents the body from properly metabolizing very long chain fatty acids. This disorder occurs in the mitochondria, where the metabolization of fatty acids takes place. Early-onset VLCADD patients usually begin to exhibit symptoms just days or weeks after birth. Hypoglycemia, lethargy and irritability are symptoms associated with this disorder. Patients will also be at risk for hypertrophic cardiomyopathy and other heart conditions from age two months to two years. It can be diagnosed through a research of family history and generally a urine analysis will reveal that the patient has reduced of absent ketone bodies. To help control acute episodes, treatment includes maintaining a high carbohydrate and low fat diet, and avoiding fasting for more than 12 hours.


Very-Long-Chain Acyl-CoA Dehydrogenase Deficiency (VLCAD),Disease

Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is a condition that prevents the body from converting certain fats to energy, particularly during periods without food (fasting). Signs and symptoms of VLCAD deficiency typically appear during infancy or early childhood and can include low blood sugar (hypoglycemia), lack of energy (lethargy), and muscle weakness. Affected individuals are also at risk for serious complications such as liver abnormalities and life-threatening heart problems. When symptoms begin in adolescence or adulthood, they tend to be milder and usually do not involve the heart. Problems related to VLCAD deficiency can be triggered by periods of fasting, illness, and exercise. This disorder is sometimes mistaken for Reye syndrome, a severe disorder that may develop in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections.


Carnitine Palmitoyl Transferase Deficiency II,Disease

Carnitine palmitoyltransferase II (CPT II) deficiency is a disorder of long-chain fatty-acid oxidation. The three clinical presentations are: lethal neonatal form, severe infantile hepatocardiomuscular form, and myopathic form that is usually mild and can manifest from infancy to adulthood. While the former two are severe multisystemic diseases characterized by liver failure with hypoketotic hypoglycemia, cardiomyopathy, seizures, and early death, the latter is characterized by exercise-induced muscle pain and weakness, sometimes associated with myoglobinuria. The myopathic form of CPT II deficiency is the most common disorder of lipid metabolism affecting skeletal muscle and is the most frequent cause of hereditary myoglobinuria. Males are more likely to be affected than females.


Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCAD),Disease

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is a condition that prevents the body from converting certain fats to energy, particularly during periods without food (fasting). Signs and symptoms of MCAD deficiency typically appear during infancy or early childhood and can include vomiting, lack of energy (lethargy), and low blood sugar (hypoglycemia). In rare cases, symptoms of this disorder first appear during adulthood. People with MCAD deficiency are at risk for serious complications such as seizures, breathing difficulties, liver problems, brain damage, coma, and sudden death.Problems related to MCAD deficiency can be triggered by periods of fasting or by illnesses such as viral infections. This disorder is sometimes mistaken for Reye syndrome, a severe disorder that may develop in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections.


Methylenetetrahydrofolate Reductase Deficiency (MTHFRD),Disease

Methylenetetrahydrofolate reductase deficiency (MTHFRD; Homocystinuria due to defect of n(5,10)-methylene THF deficiency) is caused by a defect in the MTHFR gene which codes for methylenetetrahydrofolate reductase. Methylenetetrahydrofolate reductase catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a co-substrate for homocysteine remethylation to methionine. A defect in this enzyme results in accumulation of homocysteine and methionine in both plasma and urine. Some of the symptoms and signs include mental retardation, withdrawal, hallucinations, delusions, muscle weakness. Some patients remain asymptomatic until adulthood.


Long-Chain-3-Hydroxyacyl-CoA Dehydrogenase Deficiency (LCHAD),Disease

Long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency is a rare condition that prevents the body from converting certain fats to energy, particularly during periods without food (fasting). Signs and symptoms of LCHAD deficiency typically appear during infancy or early childhood and can include feeding difficulties, lack of energy (lethargy), low blood sugar (hypoglycemia), weak muscle tone (hypotonia), liver problems, and abnormalities in the light-sensitive tissue at the back of the eye (retina). Later in childhood, people with this condition may experience muscle pain, breakdown of muscle tissue, and a loss of sensation in their arms and legs (peripheral neuropathy). Individuals with LCHAD deficiency are also at risk for serious heart problems, breathing difficulties, coma, and sudden death. Problems related to LCHAD deficiency can be triggered by periods of fasting or by illnesses such as viral infections. This disorder is sometimes mistaken for Reye syndrome, a severe disorder that may develop in children while they appear to be recovering from viral infections such as chicken pox or flu. Most cases of Reye syndrome are associated with the use of aspirin during these viral infections. Mutations in the HADHA gene cause LCHAD deficiency.


Trifunctional protein deficiency is a condition caused by mutations in the genes HADHA and HADHB. The enzyme affected is required to metabolize long-chain fatty acids, which makes a patients ability to convert fats to energy very difficult. This is exacerbated by periods without food. The symptoms associated with this disorder differ depending on when they appear in a patient. In infancy, symptoms would include lethargy, hypoglycaemia and hypotonia. Infants are also at higher risk for sudden death and heart problems. Later onset trifunctional protein deficiency symptoms also include hypotonia, but also include breakdown of muscle tissue and peripheral neuropathy. Treatment includes a low-fat, high-carbohydrate diet and avoiding fasting, as this can induce symptoms of this condition.


Congenital Lactic Acidosis,Disease

Mitochondrial DNA depletion syndrome-9 is a severe autosomal recessive disorder characterized by infantile onset of hypotonia, lactic acidosis, severe psychomotor retardation, progressive neurologic deterioration, and excretion of methylmalonic acid. Some patients die in early infancy (summary by Rouzier et al., 2010).


Fumarase Deficiency,Disease

Fumarase deficiency (or fumaric aciduria), also known as "Polygamist Down's", is an autosomal recessive metabolic disorder characterized by a deficiency of the enzyme fumarate hydratase, which is indicated by a build up of fumaric acid in the urine. (Wikipedia) Fumarase deficiency is a severe autosomal recessive metabolic disorder characterized by early-onset hypotonia, profound psychomotor retardation, and brain abnormalities, such as agenesis of the corpus callosum, gyral defects, and ventriculomegaly. Many patients show neonatal distress, metabolic acidosis, and/or encephalopathy (summary by Kerrigan et al., 2000 and Mroch et al., 2012).


Mitochondrial Complex II Deficiency,Disease

Mitochondrial complex II deficiency is a rare form of mitochondrial disease, accounting for approximately 2% of all respiratory chain deficiency diagnoses. The succinate dehydrogenase (SDH) genes (SDHA, SDHB, SDHC and SDHD) are autosomally-encoded and transcribe the conjugated heterotetramers of complex II via the action of two known assembly factors (SDHAF1 and SDHAF2). Only a handful of reports describe inherited SDH gene defects as a cause of paediatric mitochondrial disease, involving either SDHA (Leigh syndrome, cardiomyopathy) or SDHAF1 (infantile leukoencephalopathy). However, all four SDH genes, together with SDHAF2, have known tumour suppressor functions, with numerous germline and somatic mutations reported in association with hereditary cancer syndromes, including paraganglioma and pheochromocytoma.


2-Ketoglutarate Dehydrogenase Complex Deficiency,Disease

2-Ketoglutarate dehydrogenase complex deficiency is a rare autosomal recessive disease. 2-ketoglutarate dehydrogenase is an enzyme of the Krebs cycle that catalyzes the oxidation of alpha-ketoglutarate to succinyl CoA. The deficiency of 2-Ketoglutarate dehydrogenase complex results in the disorder of Krebs cycle with accumulation of succinyl CoA. The primary manifestations include developmental delay, ataxia, opisthotonus, seizure and other neurological symptoms.


Pyruvate Dehydrogenase Deficiency (E3),Disease

DLD deficiency is an autosomal recessive metabolic disorder characterized biochemically by a combined deficiency of the branched-chain alpha-keto acid dehydrogenase complex (BCKDC), pyruvate dehydrogenase complex (PDC), and alpha-ketoglutarate dehydrogenase complex (KGDC). This is the result of E3 being a common component of all 3 mitochondrial multienzyme complexes. Clinically, affected individuals have lactic acidosis and neurologic deterioration due to sensitivity of the central nervous system to defects in oxidative metabolism. E3 deficiency is often associated with increased urinary excretion of alpha-keto acids, such as pyruvate (summary by Hong et al., 1996). E3 deficiency can also be associated with increased concentrations of branched-chain amino acids, as observed in maple syrup urine disease (MSUD; 248600), and is sometimes referred to as 'MSUD type III,' although patients with E3 deficiency have additional biochemical defects (Chuang and Shih, 2001; Robinson, 2001).


Pyruvate Dehydrogenase Deficiency (E2),Disease

Pyruvate Dehydrogenase (PDH) Deficiency is an X linked disease where individuals have a reduced number of functioning PDH complexes ultimately affecting the mitochondria’s energy metabolism. In a healthy individual, PDH complex catalyzes the conversion of pyruvate to acetyl coenzyme A, therefore PDH deficiency can cause the accumulation of excess pyruvate and lactic acid. PDH deficiency presents itself in a variety of ways, however since the brain obtains most of it’s energy from aerobic oxidation of glucose, all PDH deficient individuals have some degree of neurological impairment. Other symptoms range from fatal lactic acidosis in the newborns, chronic neurodegenerative conditions, brain lesions, cerebral atrophy and much more.Due to the fatal nature of the disease many with this condition do not live past childhood, however there are some that survive to adolescents and adulthood. Treatments have tried to minimize systemic lactic acid accumulation by feeding patients high fat/low carbohydrate diets. However, this does not reverse neurological structural damage already present and therefore does little to influence the end results.


Glycogen Synthetase Deficiency,Disease

Glycogen storage disease (GSD, also glycogenosis and dextrinosis) is the result of defects in the processing of glycogen synthesis or breakdown within muscles, liver, and other cell types.[1] GSD has two classes of cause: genetic and acquired. Genetic GSD is caused by any inborn error of metabolism (genetically defective enzymes) involved in these processes. In livestock, acquired GSD is caused by intoxication with the alkaloid castanospermine.


Mucopolysaccharidosis VII. Sly Syndrome,Disease

Mucopolysaccharidosis type VII (MPS VII), also known as Sly syndrome, is a progressive condition that affects most tissues and organs. The severity of MPS VII varies widely among affected individuals. The features of MPS VII include a large head (macrocephaly), a buildup of fluid in the brain (hydrocephalus), distinctive-looking facial features that are described as "coarse," and a large tongue (macroglossia). Affected individuals also frequently develop an enlarged liver and spleen (hepatosplenomegaly), heart valve abnormalities, and a soft out-pouching around the belly-button (umbilical hernia) or lower abdomen (inguinal hernia). MPS VII causes various skeletal abnormalities that become more pronounced with age, including short stature and joint deformities (contractures) that affect mobility. Mutations in the GUSB gene cause MPS VII.


Sucrase-Isomaltase Deficiency,Disease

Congenital sucrase-isomaltase deficiency is a disorder that affects a person's ability to digest certain sugars. People with this condition cannot break down the sugars sucrose and maltose. Sucrose (a sugar found in fruits, and also known as table sugar) and maltose (the sugar found in grains) are called disaccharides because they are made of two simple sugars. Disaccharides are broken down into simple sugars during digestion. Sucrose is broken down into glucose and another simple sugar called fructose, and maltose is broken down into two glucose molecules. People with congenital sucrase-isomaltase deficiency cannot break down the sugars sucrose and maltose, and other compounds made from these sugar molecules (carbohydrates). Congenital sucrase-isomaltase deficiency usually becomes apparent after an infant is weaned and starts to consume fruits, juices, and grains. After ingestion of sucrose or maltose, an affected child will typically experience stomach cramps, bloating, excess gas production, and diarrhea. These digestive problems can lead to failure to gain weight and grow at the expected rate (failure to thrive) and malnutrition. Most affected children are better able to tolerate sucrose and maltose as they get older.


Pyruvate Kinase Deficiency,Disease

Pyruvate kinase deficiency is a genetic disorder. It affects red blood cells in the body. Patients are affected by a condition called chronic hemolytic anemia, which is where red blood cells undergo hemolysis before they are meant to which causes anemia in the patient. Symptoms of this condition can include jaundice, fatigue, dyspnea and splenomegaly. Gallstones are also common to patients with this disorder. This disorder is diagnosed through genetic testing. In mild cases, no treatment is required. Patients with more severe cases may require blood transfusions, and occasionally the spleen is removed to aid with the reduction of red blood cell destruction.


Phosphoenolpyruvate Carboxykinase Deficiency 1 (PEPCK1),Disease

Phosphoenolpyruvate carboxykinase deficiency 1 (pepck1) is a rare congenital metabolic disease caused by mutation of the phosphoenolpyruvate carboxykinase gene. Phosphoenolpyruvate carboxykinase (PEPCK) is an enzyme in the lyase family used in the metabolic pathway of gluconeogenesis. It converts oxaloacetic acid into phosphoenolpyruvate and carbon dioxide. Deficiency of Phosphoenolpyruvate carboxykinase results in metabolic disorder with impaired gluconeogenesis. The clinical characteristics include hypotonia, failure to thrive, hepatomegaly, lactic acidosis and hypoglycemia.


Fructosuria,Disease

Essential fructosuria is a benign, asymptomatic defect of intermediary metabolism characterized by the intermittent appearance of fructose in the urine (summary by Bonthron et al., 1994). Essential fructosuria caused by a deficiency of the enzyme hepatic fructokinase is a clinically benign condition characterized by the incomplete metabolism of fructose in the liver, leading to its excretion in urine. Essential fructosuria is a genetic condition that is inherited in an autosomal recessive manner.Mutations in the KHK gene, located on chromosome 2p23.3-23.2 are responsible.


Triosephosphate isomerase deficiency is a genetic disorder caused by a mutation in the TPI1 gene. The mutation of this gene causes the production of enzymes that are unstable or enzymes that have reduced activity. This means that cells have reduced energy supplies as glycolysis is compromised. This disorder causes anemia, movement problems and muscle weakness. As a result of the lack of red blood cells to carry oxygen through the body, patients may experience fatigue and shortness of breath. Movement problems appear in early infancy, typically before the age of 2 in patients with this disorder. Treatment includes blood transfusions.


Aromatase Deficiency,Disease

Aromatase deficiency is a rare autosomal recessive disorder caused by mutations in the CYP19A1 gene and characterized by lack of conversion of androgens to estrogens. It presents with virilization of pregnant mothers during the antenatal period, and virilization of female fetuses at birth. Affected subjects of either gender later manifest with features of estrogen deficiency and androgen excess.


Congenital adrenal hyperplasia (CAH) refers to any of several autosomal recessive diseases resulting from mutations of genes for enzymes mediating the biochemical steps of production of cortisol from cholesterol by the adrenal glands (steroidogenesis). Most of these conditions involve excessive or deficient production of sex steroids and can alter development of primary or secondary sex characteristics in some affected infants, children, or adults.


Succinic Semialdehyde Dehydrogenase Deficiency,Disease

Succinic Semialdehyde Dehydrogenase (SSADH) deficiency is a rare autosomal recessive inherited disorder affecting the metabolism of γ-aminobutyric acid (GABA). With reduced GABA activity, oxidation of succinic semialdehyde (SSA) to succinic acid is impaired causing a build up of SSA and ultimately it’s downstream metabolite γ-hydroxybutyric acid (GHB). Symptoms of SSADH deficiency are primarily neuropsychiatric including developmental delays, hypotonia, expressive language impairment, seizures, difficulty coordinating movements (ataxia), decreased reflexes (hyporeflexia), and other behavioral issues. Patients with SSADH deficiency have elevated levels of GHB in urine, however this method is not a definitive diagnosis due to the potential volatilization of acidified urine and the use of GHB as a drug. Instead SSADH can be confirmed suing enzyme analysis in leukocytes and molecular genetic analysis of the Aldh5a1 gene at chromosome 6p22.


Short-Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency (SCHAD),Disease

3-hydroxyacyl-CoA dehydrogenase deficiency is an inherited condition that prevents the body from converting certain fats to energy, particularly during prolonged periods without food (fasting). Initial signs and symptoms of this disorder typically occur during infancy or early childhood and can include poor appetite, vomiting, diarrhea, and lack of energy (lethargy). Affected individuals can also have muscle weakness (hypotonia), liver problems, low blood sugar (hypoglycemia), and abnormally high levels of insulin (hyperinsulinism). Mutations in the HADH gene cause 3-hydroxyacyl-CoA dehydrogenase deficiency.


Succinyl CoA: 3-Ketoacid CoA Transferase Deficiency,Disease

Succinyl CoA: 3-Ketoacid CoA Transferase (SCOT) deficiency is a rare inherited metabolic disorder causing reduction of ketone body utilization. In normal functioning patients, ketone bodies such as Acetoacetate (AcAc) and 3‐hydroxybutyrate (3HB) are metabolized inside the liver from free fatty acids. Next, ketone bodies are transported to extrahepatic tissues via the blood stream. Once in extrahepatic tissues, SCOT converts AcAc to acetoacetyl‐CoA and T2 cleaves acetoacetyl‐CoA into acetyl‐CoA. This process is crucial for producing alternative energy sources to glucose in order to maintain blood glucose levels. Patients with SCOT deficiency have this process disturbed and ketoacidosis which is the acidification of the bloodstream due to excess ketone body accumulation, can occur. Current treatments include avoiding actions that could onset ketoacidosis such as fasting and early infusion of glucose.The severity of SCOT deficiency differs from patient to patient. Some exhibit severe genotypes where ketones are always in abundance in the body, while others could have mild genotypes with no preeminent ketosis however both could exhibit ketoacidotic episodes.


Pyridoxine Dependency with Seizures,Disease

Pyridoxine-dependent epilepsy is a condition that involves seizures beginning in infancy or, in some cases, before birth. Those affected typically experience prolonged seizures lasting several minutes (status epilepticus). These seizures involve muscle rigidity, convulsions, and loss of consciousness (tonic-clonic seizures). Additional features of pyridoxine-dependent epilepsy include low body temperature (hypothermia), poor muscle tone (dystonia) soon after birth, and irritability before a seizure episode. In rare instances, children with this condition do not have seizures until they are 1 to 3 years old. Anticonvulsant drugs, which are usually given to control seizures, are ineffective in people with pyridoxine-dependent epilepsy. Instead, people with this type of seizure are medically treated with large daily doses of pyridoxine (a type of vitamin B6 found in food). If left untreated, people with this condition can develop severe brain dysfunction (encephalopathy). Even though seizures can be controlled with pyridoxine, neurological problems such as developmental delay and learning disorders may still occur.


Fanconi-Bickel Syndrome,Disease

Fanconi-Bickel syndrome (FBS) is a rare autosomal recessive disorder of carbohydrate metabolism recently demonstrated to be caused by mutations in Glut2, the gene for the glucose transporter protein 2 expressed in liver, pancreas, intestine and kidney. The disease was first described in a 3-year-old Swiss boy in 1949.


Congenital adrenal hyperplasia (CAH) due to 11-beta-hydroxylase deficiency is one of a group of disorders (collectively called congenital adrenal hyperplasia) that affect the adrenal glands. The adrenal glands are located on top of the kidneys and produce a variety of hormones that regulate many essential functions in the body. In people with CAH due to 11-beta-hydroxylase deficiency, the adrenal glands produce excess androgens, which are male sex hormones. There are two types of CAH due to 11-beta-hydroxylase deficiency, the classic form and the non-classic form. The classic form is the more severe of the two types.


Congenital adrenal hyperplasia (CAH) refers to any of several autosomal recessive diseases resulting from mutations of genes for enzymes mediating the biochemical steps of production of cortisol from cholesterol by the adrenal glands (steroidogenesis). 21-hydroxylase deficiency is an inherited disorder that affects the adrenal glands. The adrenal glands are located on top of the kidneys and produce a variety of hormones that regulate many essential functions in the body. In people with 21-hydroxylase deficiency, the adrenal glands produce excess androgens, which are male sex hormones. There are three types of 21-hydroxylase deficiency. Two types are classic forms, known as the salt-wasting and simple virilizing types. The third type is called the non-classic type. The salt-wasting type is the most severe, the simple virilizing type is less severe, and the non-classic type is the least severe form.


Corticosterone Methyl Oxidase I Deficiency (CMO I),Disease

Corticosterone methyloxidase type I (CMO-I) deficiency is an autosomal recessively inherited disorder causing congenital hypoaldosteronism due to defects in aldosterone synthase (P450aldo), the enzyme that converts 11-deoxycorticosterone to corticosterone, 18-hydroxycorticosterone, and aldosterone.


Corticosterone Methyl Oxidase II Deficiency (CMO II),Disease

CMO type II deficiency is an autosomal recessive disorder caused by a defect in the final biochemical step of aldosterone biosynthesis, the 18-hydroxylation of 18-hydroxycorticosterone (18-OHB) to aldosterone. This enzymatic defect results in decreased aldosterone and salt-wasting associated with an increased serum ratio of 18-OHB to aldosterone. In CMO II deficiency, aldosterone can be low or normal, but at the expense of increased secretion of 18-OHB. These patients have a low ratio of corticosterone to 18-OHB (Portrat-Doyen et al., 1998). The CYP11B2 gene product also catalyzes an earlier step in aldosterone biosynthesis: the 18-hydroxylation of corticosterone to 18-OHB. A defect in that enzymatic step results in CMO type I deficiency (204300), an allelic disorder with an overlapping phenotype but distinct biochemical features. In CMO I deficiency, aldosterone is undetectable, whereas its immediate precursor, 18-OHB, is low or normal (Portrat-Doyen et al., 1998).


Congenital Disorder of Glycosylation CDG-IId,Disease

Congenital disorders of glycosylation (CDGs) are a genetically heterogeneous group of autosomal recessive disorders caused by enzymatic defects in the synthesis and processing of asparagine (N)-linked glycans or oligosaccharides on glycoproteins. These glycoconjugates play critical roles in metabolism, cell recognition and adhesion, cell migration, protease resistance, host defense, and antigenicity, among others. CDGs are divided into 2 main groups: type I CDGs (see, e.g., CDG1A, 212065) comprise defects in the assembly of the dolichol lipid-linked oligosaccharide (LLO) chain and its transfer to the nascent protein, whereas type II CDGs refer to defects in the trimming and processing of the protein-bound glycans either late in the endoplasmic reticulum or the Golgi compartments. The biochemical changes of CDGs are most readily observed in serum transferrin (TF; 190000), and the diagnosis is usually made by isoelectric focusing of this glycoprotein (reviews by Marquardt and Denecke, 2003; Grunewald et al., 2002).


GLUT-1 Deficiency Syndrome,Disease

GLUT1 deficiency syndrome is a disorder that primarily affects the brain. Affected individuals generally have seizures beginning in the first few months of life. Babies with GLUT1 deficiency syndrome have a normal head size at birth, but growth of the brain and skull is often slow, in severe cases resulting in an abnormally small head size (microcephaly). People with GLUT1 deficiency syndrome may have developmental delay or intellectual disability. They may also have other neurological problems, such as stiffness caused by abnormal tensing of the muscles (spasticity), difficulty in coordinating movements (ataxia), and speech difficulties (dysarthria). Some experience episodes of confusion, lack of energy (lethargy), headaches, muscle twitches (myoclonus), or involuntary irregular eye movements, particularly before meals.


Joubert Syndrome,Disease

Joubert syndrome is a disorder that affects many parts of the body. The signs and symptoms of this condition vary among affected individuals, even among members of the same family. The hallmark feature of Joubert syndrome is a brain abnormality called the molar tooth sign, which can be seen on brain imaging studies such as magnetic resonance imaging (MRI). This sign results from the abnormal development of regions near the back of the brain called the cerebellar vermis and the brainstem. The molar tooth sign got its name because the characteristic brain abnormalities resemble the cross-section of a molar tooth when seen on an MRI.


Blue Diaper Syndrome,Disease

Blue diaper syndrome is a rare, autosomal recessive metabolic disorder characterized in infants by bluish urine-stained diapers. It is caused by a defect in tryptophan absorption. Bacterial degradation of tryptophan in the intestine leads to excessive indole production and thus to indicanuria which, on oxidation to indigo blue, causes a peculiar bluish discoloration of the diaper. Symptoms typically include digestive disturbances, fever and visual problems.


Lysinuric Protein Intolerance (LPI),Disease

Lysinuric protein intolerance is a disorder caused by the body's inability to digest and use certain protein building blocks (amino acids), namely lysine, arginine, and ornithine. Because the body cannot effectively break down these amino acids, which are found in many protein-rich foods, nausea and vomiting are typically experienced after ingesting protein. Mutations in the SLC7A7 gene cause lysinuric protein intolerance. The SLC7A7 gene provides instructions for producing a protein called y+L amino acid transporter 1 (y+LAT-1), which is involved in transporting lysine, arginine, and ornithine between cells in the body.


Coagulation ,Protein

Blood coagulation can be initiated by either an extrinsic or an intrinsic pathway, resulting in a cascade of serine protease activation that ultimately leads to the formation of thrombin, which converts soluble fibrinogen to an insoluble fibrin clot. The extrinsic, or tissue factor, pathway is initiated upon vascular injury, when the membrane-bound protein tissue factor (TF) comes into contact with factor VII or VIIa in plasma. The TF-VIIa complex is the strongest known activator of the coagulation cascade, and converts factors IX and X to IXa and Xa, respectively. Factors VII, IX, and X are vitamin-K-dependent proteins produced in the liver. In the intrinsic, or contact, pathway, injury exposes collagen to the bloodstream where is binds to factor XII and activates it to XIIa. Factor XIIa converts prekallikrein to kallikrein and factor XI to XIa. Both the extrinsic and intrinsic pathways result in the activation of factor IX to IXa, which forms the 'tenase' complex with factor VIIIa, calcium and phospholipids. This complex converts factor X to Xa and is important in haemostasis. Factor Xa complexes with factor Va (which functions as a non-enzymatic cofactor), calcium and a phospholipid membrane surface to form what is called the prothrombinase complex, which converts prothrombin to thrombin. Thrombin converts soluble fibrinogen to insoluble fibrin polymer, which is stabilized by cross-linking by coagulation factor XIIIa.


Angiotensin Metabolism,Physiological

Angiotensin is a peptide hormone that is part of the renin-angiotensin system responsible for regulating fluid homeostasis and blood pressure.   It is involved in various means to increase the body's blood pressure, hence why it is a target for many pharmceutical drugs that treat hypertension and cardiac conditions.  Angiotensin II, the primary agent to inducing an increased blood pressure, is formed in the general circulation when it is cleaved from a string of precursor molecules.  Angiotensinogen is converted into angiotensin I with the action of renin, an enzyme secreted from the kidneys.  From there, angiotensin I is converted to the central agent, angiotensin II, with the aid of angiotensin-converting enzyme (ACE) so that it is available in the circulation to act on numerous areas in the body when an increase in blood pressure is needed.  Angiotensin II can act directly on receptors on the smooth muscle cells of the tunica media layer in the blood vessel to induce vasoconstriction and a subsequent increase in blood pressure.  However, it can also influence the blood pressure by aiding in an increase of the circulating blood volume.  Angiotensin II can cause vasopressin to be released, which is a hormone involved in regulating water reabsorption.  Vasopressin is created in the supraoptic nuclei and they travel down the neurosecretory neuron axon to be stored in the neuronal terminals within the posterior pituitary.  Angiotensin II in the cerebral circulation triggers the release of vasopressin from the posterior pituitary gland.  From there, vasopressin enters into the systemic blood circulation where it eventually binds to receptors on epithelial cells in the collecting ducts of the nephron.   The binding of vasopressin causes vesicles of epithelial cells to fuse with the plasma membrane.  These vesicles contain aquaporin II, which are proteins that act as water channels once they have bound to the plasma membrane.  As a result, the permeability of the collecting duct changes to allow for water reabsorption back into the blood circulation.  Angiotensin II also has an effect on the hypothalmus, where it helps trigger a thirst sensation.  Correspondingly, there will be an increase in oral water uptake into the body, which would then also increase the circulating blood volume.  Another way that angiotensin II helps increase the blood volume is by acting on the adrenal cortex to stimulate aldosterone release, which is responsible for increasing sodium reuptake in the distal convoluted tubules and the collecting duct.  It is formed when angiotensin II binds to receptors on the zona glomerulosa cells in the adrenal cortex, which triggers a signaling cascade that eventually activates the steroidogenic acute regulatory (StAR) protein to allow for cholesterol uptake into the mitochondria.  Cholesterol then undergoes a series of reactions during steroidogenesis, which is a process that ultimately leads to the synthesis of aldosterone from cholesterol. Aldosterone then goes to act on the distal convoluted tubule and the collecting duct to make them more permeable to sodium to allow for its reuptake.  Water subsequently follows sodium back into the system, which would therefore increase the circulating blood volume.  In addition, potassium and hydrogen are also being excreted into the urine simultaneously to maintain the electrolyte balance.


Tubular striated muscle cells (i.e. skeletal and cardiac myocytes) are composed of bundles of rod-like myofibrils. Each individual myofibril consists of many repeating units called sarcomeres. These functional units, in turn, are composed of many alternating actin and mysoin protein filaments that produce muscle contraction.  The muscle contraction process is initiated when the muscle cell is depolarized enough for an action potential to occur. When acetylcholine is released from the motor neuron axon terminals that are adjacent to the muscle cells, it binds to receptors on the sarcolemma (muscle cell membrane), causing nicotinic acetylcholine receptors to be activated and the sodium/potassium channels to be opened. The fast influx of sodium and slow efflux of potassium through the channel causes depolarization.  The resulting action potential that is generated travels along the sarcolemma and down the T-tubule, activating the L-type voltage-dependent calcium channels on the sarcolemma and ryanodine receptors on the sarcoplasmic reticulum. When these are activated, it triggers the release of calcium ions from the sarcoplasmic reticulum into the cytosol. From there, the calcium ions bind to the protein troponin which displaces the tropomysoin filaments from the binding sites on the actin filaments.  This allows for myosin filaments to be able to bind to the actin.  According to the Sliding Filament Theory, the myosin heads that have an ADP and phosphate attached binds to the actin, forming a cross-bridge.  Once attached, the myosin performs a powerstroke which slides the actin filaments together.  The ATP and phosphate are dislodged during this process.  However, ATP now binds to the myosin head, which causes the myosin to detach from the actin.  The cycle repeats once the attached ATP dissociates into ADP and phosphate, and the myosin performs another powerstroke, bringing the actin filaments even closer together.  Numerous actin filaments being pulled together simultaneously across many muscles cells triggers muscle contraction.


Gastric Acid Production,Physiological

Gastric acid plays a key role in the digestion of proteins by activating digestive enzymes to break down long chains of amino acids. In addition, it aids in the absorption of certain vitamins and minerals and also acts as one of the body's first line of defence by killing ingested micro-organisms.  This digestive fluid is formed in the stomach (specifically by the parietal cells) and is mainly composed of hydrochloric acid (HCl).  However, it is also constituted of potassium chloride (KCl) and sodium chloride (NaCl). The main stimulants of acid secretion are histamine, gastrin, and acetylcholine which all, after binding to their respective receptors on the parietal cell membrane, trigger a G-protein signalling cascade that causes the activation of the H+/K+ ATPase proton pump. As a result, hydrogen ions are able to be pumped out of the parietal cell and into the lumen of the stomach.  The hydrogen ions are available inside the parietal cell after water and carbon dioxide combine to form carbonic acid(the reaction is catalyzed by the carbonic anhydrase enzyme) which dissociates into a bicarbonate ion and a hydrogen ion.  Moreover, the chloride and potassium ions are transported into the stomach lumen through their own channels so that hydrogen ions and/or potassium ions can form an ionic bond with chloride ions to form HCl and/or KCl, which are both constituents of stomach acid.  In addition, the peptide hormone somatostatin is the main inhibitor to gastric acid secretion.  Not only does it inhibit the G-protein signalling cascade that leads to proton pump activation, but it also directly acts on the enterochromaffin-like cells and G cells to inhibit histamine and gastrin release, respectively.


Ibuprofen Metabolism Pathway,Drug Metabolism

Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID) used for its analgesic, antipyretic and anti-inflammatory properties. Like most NSAIDs, ibuprofen is a non-selective inhibitor of prostaglandin G/H synthase 1 and 2, better known as cyclooxygenase 1 and 2 or simply COX-1 and -2. COX catalyzes the conversion of arachidonic acid to a number of prostaglandins involved in fever, pain, swelling, inflammation, and platelet aggregation. Ibuprofen antagonizes COX by binding to the upper portion of the active site, preventing its substrate, arachidonic acid, from entering the active site. The analgesic, antipyretic and anti-inflammatory effects of ibuprofen occurs as a result of decreased prostaglandin synthesis. Ibuprofen is slightly more potent than aspirin and produces analgesic effects at lower doses than aspirin. Unlike aspirin, ibuprofen is a reversible COX inhibitor and thus it is not used as an antiplatelet agent.


Benazepril Metabolism Pathway,Drug Metabolism

Benazepril, brand name Lotensin, belongs to the class of drugs known as angiotensin-converting enzyme (ACE) inhibitors and is used primarily to lower high blood pressure (hypertension). This drug can also be used in the treatment of congestive heart failure and type II diabetes. Benazepril is a prodrug which, following oral administration, undergoes biotransformation in vivo into its active form benazeprilat via cleavage of its ester group by the liver. Angiotensin-converting enzyme (ACE) is a component of the body's renin–angiotensin–aldosterone system (RAAS) and cleaves inactive angiotensin I into the active vasoconstrictor angiotensin II. ACE (or kininase II) also degrades the potent vasodilator bradykinin. Consequently, ACE inhibitors decrease angiotensin II concentrations and increase bradykinin concentrations resulting in blood vessel dilation and thereby lowering blood pressure.


Cilazapril Metabolism Pathway,Drug Metabolism


Enalapril Metabolism Pathway,Drug Metabolism


Fosinopril Metabolism Pathway,Drug Metabolism


Moexipril Metabolism Pathway,Drug Metabolism


Quinapril Metabolism Pathway,Drug Metabolism


Ramipril Metabolism Pathway,Drug Metabolism


Spirapril Metabolism Pathway,Drug Metabolism


Trandolapril Metabolism Pathway,Drug Metabolism


Irinotecan Metabolism Pathway,Drug Metabolism

Irinotecan is a topoisomerase I inhibitor used in the treatment of cancer. It is hydrolyzed by esterases in the liver, intestine, and cytoplasm into the active metabolite SN-38, which binds to and inhibits the function of topoisomerase I. Topoisomerase I unwinds DNA by making transient single strand breaks that relieves the torsion of supercoiled DNA. In the unwound form, DNA can serve as a template for DNA replication as well as transcription. In the normal state, this effect is transient and the breaks DNA are quickly religated by topoisomerase I itself. SN-38 binding, however, inhibits religation and stabilizes the DNA-topoisomerase I complex in the cleaved DNA form, ultimately leading to breaks in both DNA chains and cell death.


Etoposide Metabolism Pathway,Drug Metabolism

Etoposide is an podophyllotoxin derative that is used in the treatment of certain cancers. It inhibits mitosis and induces cell death by acting as a topoisomerase II poison. Topoisomerase II is an enzyme in the nucleus of cells that unwinds DNA by making transient double-stranded breaks, relieving the torsion of supercoiled DNA. In the unwound form, DNA can serve as a template for DNA replication as well as transcription. In the normal state, this effect is transient and the breaks DNA are quickly religated by topoisomerase II itself. Etoposide, however, inhibits religation and stabilizes the DNA-topoisomerase II complex in the cleaved DNA form, ultimately leading to breaks in both DNA chains and cell death.Etoposide is also converted into catechol and o-quinone derivatives in the liver and in lysosomes respectively. These metabolites are highly oxidative and can directly damage DNA, which may also contribute to the drug’s cytotoxic effects.


Teniposide Metabolism Pathway,Drug Metabolism

Teniposide is an podophyllotoxin derative that is used in the treatment of certain cancers. It inhibits mitosis and induces cell death by acting as a topoisomerase II poison. Topoisomerase II is an enzyme in the nucleus of cells that unwinds DNA by making transient double strand breaks, relieving the torsion of supercoiled DNA. In the unwound form, DNA can serve as a template for DNA replication as well as transcription. In the normal state, this effect is transient and the breaks DNA are quickly religated by topoisomerase II itself. Teniposide, however, inhibits religation and stabilizes the DNA-topoisomerase II complex in the cleaved DNA form, ultimately leading to breaks in both DNA chains and cell death.Teniposide is also converted into catechol and o-quinone derivatives in the liver and in lysosomes respectively. These metabolites are highly oxidative and can directly damage DNA, which may also contribute to the drug’s cytotoxic effects.


Gemcitabine Metabolism Pathway,Drug Metabolism

Gemcitabine is a cytidine analogue used in the treatment of certain cancers. Gemcitabine enters the cell via sodium nucleoside co-transporters (SLC29A1, SLC28A1, and SLC28A3), where it acts through multiple mechanisms to produce a cytotoxic effect. Gemcitabine is phosphorylated into gemcitabine monophosphate by deoxycytidine kinase, which is then subsequently phosphorylated into the diphosphate and triphosphate nucleotides by UMP-CMP kinase and nucleoside diphosphate kinase respectively. Gemcitabine diphosphate inhibits ribonucleoside-diphosphate reductase, a crucial enzyme in the conversion of ribonucleotides into deoxyribonucleotides for DNA synthesis. Gemcitabine triphosphate on the other hand can be incorporated into DNA, causing chain termination. Furthermore, gemcitabine monophosphate can be deaminated into difluoro-deoxyuridine monophosphate, which inhibits thymidylate synthase, an enzyme involved in the production of dTTP for DNA synthesis.


Cyclophosphamide Metabolism Pathway,Drug Metabolism

Cyclophosphamide is an alkylating agent used in the treatment of certain cancers. Following absorption, cyclophosphamide is converted into 4-hydroxyphosphamide by a variety of cytochrome P450 isozymes in the liver. 4-Hydroxyphosphamide is more soluble than cyclophosphamide and is the primary form of the drug that is transported in blood. 4-Hydroxyphosphamide crosses the plasma membrane of the cancer cell and spontaneuosly forms aldophosphamide. This is a reversible reaction. Aldophosphamide can decompose into acrolein and phosphoramide mustard. Phosphoramide mustard is the active alkylating agent and forms alkyl adducts with DNA through a phosphoramide aziridinium intermediate. Alkylation of DNA causes DNA damage and eventually cell death.


Ifosfamide Metabolism Pathway,Drug Metabolism

Ifosfamide is an alkylating agent used in the treatment of certain cancers. Following absorption, ifosfamide is converted into 4-hydroxyifosfamide by a variety of cytochrome P450 isozymes in the liver. 4-Hydroxyifosfamide crosses the plasma membrane of the cancer cell and spontaneuosly forms aldoifosfamide. This is a reversible reaction. Aldoifosfamide can decompose into acrolein and ifosforamide mustard. Ifosforamide mustard is the active alkylating agent and forms alkyl adducts with DNA through an ifosforamide aziridinium intermediate. Alkylation of DNA causes DNA damage and ultimately cell death.


Tamoxifen Metabolism Pathway,Drug Metabolism

Tamoxifen is a selective estrogen modulator (SERM) used in the treatment of estrogen-sensitive breast cancer. Tamoxifen itself only has weak anti-estrogen effects and must be converted into more active metabolites to have therapeutic activity. Metabolism takes place in the liver and is carried out primarily by cytochrome P450 enzymes. Tamoxifen is hydroxylated by CYP2D6 and demethylated by CYP3A4 and CYP3A5, producing the active metabolites 4-hydroxytamoxifen and endoxifen. These metabolites inhibit estrogen binding to estrogen receptors in breast cancer cells, which in turn inhibit tumour growth.


Capecitabine Metabolism Pathway,Drug Metabolism

Capecitabine is a fluoropyrimidine anticancer drug. After absorption, it is metabolized in the liver to the intermediate 5’-deoxy-5-fluorouridine, which is subsequently converted into 5-fluorouracil (5-FU) by intracellular thymidine phosphorylase. 5-FU exerts cytotoxic effects on the cell by direct incorporation into DNA and RNA as well as by inhibiting thymidylate synthase. Since thymidine phosphorylase is present at 3-10 fold higher concentration in cancer cells compared normal cells, capecitabine’s cytotoxic effect is selective for cancer cells.


Fluorouracil Metabolism Pathway,Drug Metabolism

Fluorouracil (5-FU), sold under the brand name Adrucil among others, is a fluoropyrimidine anticancer drug. By injection into a vein, it is used to treat colon cancer, esophageal cancer, stomach cancer, pancreatic cancer, breast cancer, and cervical cancer. As a cream, it is used for actinic keratosis, basal cell carcinoma, and skin warts. Fluorouracil is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system (Wikipedia). Fluorouracil exerts cytotoxic effects on the cell by direct incorporation into DNA and RNA as well as by inhibiting thymidylate synthase.


Mercaptopurine Metabolism Pathway,Drug Metabolism

Mercaptopurine is a purine antimetabolite prodrug that exerts cytotoxic effects via three mechanisms: via incorporation of thiodeoxyguanosine triphosphate into DNA and thioguanosine triphosphate into RNA, inhibition of de novo synthesis of purine nucleotides, and inhibition of Ras-related C3 botulinum toxin substrate 1, which induces apoptosis of activated T cells. Mercaptopurine travels through the bloodstream and is transported into cells via nucleoside transporters.  Mercaptopurine is then converted to thioguanosince diphosphate through a series of metabolic reactions that produces the metabolic intermediates, thioinosine 5’-monophosphate, thioxanthine monophosphate, and thioguanosine monophosphate. Thioguanosine diphosphate is then converted via a thiodeoxyguanosine diphosphate intermediate to thiodeoxyguanosine triphosphate, which is incorporated into DNA. Thioguanosine diphosphate is also converted to thioguanosine triphosphate which is incorporated into RNA. The thioguanosine triphosphate metabolite also inhibits Ras-related C3 botulinum toxin substrate 1, a plasma membrane-associated small GTPase that regulates cellular processes, inducing apoptosis in activated T cells. Finally, de novo synthesis of purine nucleotides is inhibited by the methyl-thioinosine 5’-monophosphate metabolite, which inhibits amidophosphoribosyl-transferase, the enzyme that catalyzes one of the first steps in this pathway.


Clopidogrel Metabolism Pathway,Drug Metabolism

Clopidogrel, an antiplatelet agent structurally and pharmacologically similar to ticlopidine, is used to reduce atherosclerotic events such as myocardial infarction, stroke, and vascular death in patients who have had a recent stroke, recent MI, or have established peripheral vascular disease. The active metabolite of clopidogrel prevents binding of adenosine diphosphate (ADP) to its platelet receptor, impairing the ADP-mediated activation of the glycoprotein GPIIb/IIIa complex. It is proposed that the inhibition involves a defect in the mobilization from the storage sites of the platelet granules to the outer membrane. No direct interference occurs with the GPIIb/IIIa receptor. As the glycoprotein GPIIb/IIIa complex is the major receptor for fibrinogen, its impaired activation prevents fibrinogen binding to platelets and inhibits platelet aggregation. By blocking the amplification of platelet activation by released ADP, platelet aggregation induced by agonists other than ADP is also inhibited by the active metabolite of clopidogrel.


Ticlopidine Metabolism Pathway,Drug Metabolism

Ticlopidine, marketed as Ticlid, is an antiplatelet drug that targets the P2Y12 receptor of platelets. Ticlopidine is taken orally and is a prodrug that must be metabolically activated before it can be effective. It first enters the liver and enters the endoplasmic reticulum where it is metabolized to form the active metabolite. First, it is catalyzed by cytochromes P450 2C19, 2B6 and 1A2 into 2-oxoclopidogrel. Secondly, it is processed by cytochromes P450 2B6, 2C9, 2C19, 3A4, 3A5, and serum paraoxonase/arylesterase 1 into the active metabolite of clopidogrel. The active metabolite of clopidogrel then enters the blood stream, where it binds irreversibly to the P2Y purinoreceptor 12 on the surface of platelet cells, preventing ADP from binding to and activating it. Clopidogrel prevents the activation of the Gi protein associated with the P2Y12 receptor from inactivating adenylate cyclase in the platelet, leading to a buildup of cAMP. This cAMP then activates calcium efflux pumps, preventing calcium buildup in the platelet, which would cause activation, and later, aggregation.


Esomeprazole Metabolism Pathway,Drug Metabolism

Esomeprazole is a compound that inhibits gastric acid secretion and is indicated in the treatment of gastroesophageal reflux disease (GERD), the healing of erosive esophagitis, and H. pylori eradication to reduce the risk of duodenal ulcer recurrence. Esomeprazole belongs to a new class of antisecretory compounds, the substituted benzimidazoles, that do not exhibit anticholinergic or H2 histamine antagonistic properties, but that suppress gastric acid secretion by specific inhibition of the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. Because this enzyme system is regarded as the acid (proton) pump within the gastric mucosa, Esomeprazole has been characterized as a gastric acid-pump inhibitor, in that it blocks the final step of acid production. This effect is dose-related and leads to inhibition of both basal and stimulated acid secretion irrespective of the stimulus.


Omeprazole Metabolism Pathway,Drug Metabolism

Omeprazole is a compound that inhibits gastric acid secretion and is indicated in the treatment of gastroesophageal reflux disease (GERD), the healing of erosive esophagitis, and H. pylori eradication to reduce the risk of duodenal ulcer recurrence. Omeprazole belongs to a new class of antisecretory compounds, the substituted benzimidazoles, that do not exhibit anticholinergic or H2 histamine antagonistic properties, but that suppress gastric acid secretion by specific inhibition of the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. Because this enzyme system is regarded as the acid (proton) pump within the gastric mucosa, omeprazole has been characterized as a gastric acid-pump inhibitor, in that it blocks the final step of acid production. This effect is dose-related and leads to inhibition of both basal and stimulated acid secretion irrespective of the stimulus.


Lansoprazole Metabolism Pathway,Drug Metabolism

Lansoprazole belongs to a class of antisecretory compounds, the substituted benzimidazoles, that do not exhibit anticholinergic or histamine H2-receptor antagonist properties, but rather suppress gastric acid secretion by specific inhibition of the (H+,K+)-ATPase enzyme system at the secretory surface of the gastric parietal cell. Because this enzyme system is regarded as the acid (proton) pump within the parietal cell, Lansoprazole has been characterized as a gastric acid-pump inhibitor, in that it blocks the final step of acid production. This effect is dose-related and leads to inhibition of both basal and stimulated gastric acid secretion irrespective of the stimulus.


Pantoprazole Metabolism Pathway,Drug Metabolism

Pantoprazole is a proton pump inhibitor (PPI) that suppresses the final step in gastric acid production by forming a covalent bond to two sites of the (H+,K+ )- ATPase enzyme system at the secretory surface of the gastric parietal cell. This effect is dose-related and leads to inhibition of both basal and stimulated gastric acid secretion irrespective of the stimulus.


Rabeprazole Metabolism Pathway,Drug Metabolism

Rabeprazole is a drug that belongs to the anti secretory drug class. It is used as an anti-ulcer medication, and helps relieve gastric acid reflux, gastric irritation and gastric pain. It inhibits the proton pump action of ATPase, which blocks the final step of gastric acid secretion. The pathway begins in the parietal cell in the stomach, where rabeprazole and a hydrogen ion use the active metabolite in rabeprazole —rabeprazole thioether — to inhibit potassium-transporting ATPase at the secretory surface of the gastric parietal cell. Now in the gastric endothelial cell, these secretory surfaces are inhibited by rabeprazole and by G-Protein signalling cascade through somatostatin receptor type 4, which is activated by somatostatin. At the same time, potassium-transporting ATPase is activated by the G-protein signalling cascade, through histamine H2 receptor, gastrin/cholecystokinin type B receptor, and muscarinic acetylcholine receptor M3 which are activated by histamine, gastrin and acetylcholine, respectively. The potassium transporting ATPase also converts water and ATP to a phosphate molecule and ADP. Alongside the transporters, potassium is brought into the cell. Carbonic anhydrase 1 uses water and carbon dioxide to create hydrogen carbonate and a hydrogen ion, which are both transported out of the endothelial cell, into the gastric lumen. A chloride ion is transported into the gastric endothelial cell through a chloride anion exchanger and is transported out of the cell through a chloride intracellular channel protein 2, back into the gastric lumen.


Cimetidine Metabolism Pathway,Drug Metabolism

Cimetidine binds to histamine H2-receptors located on the basolateral membrane of the gastric parietal cell, blocking histamine effects. This competitive inhibition results in reduced gastric acid secretion and a reduction in gastric volume and acidity.


Fosphenytoin (Antiarrhythmic) Metabolism Pathway,Drug Metabolism

This pathway illustrates the fosphenytoin targets involved in antiarrhythmic therapy. Contractile activity of cardiac myocytes is elicited via action potentials mediated by a number of ion channel proteins. During rest, or diastole, cells maintain a negative membrane potential; i.e. the inside the cell is negatively charged relative to the cells’ extracellular environment. Membrane ion pumps, such as the sodium-potassium ATPase and sodium-calcium exchanger (NCX), maintain low intracellular sodium (5 mM) and calcium (100 nM) concentrations and high intracellular potassium (140 mM) concentrations. Conversely, extracellular concentrations of sodium (140 mM) and calcium (1.8 mM) are relatively high and extracellular potassium concentrations are low (5 mM). At rest, the cardiac cell membrane is impermeable to sodium and calcium ions, but is permeable to potassium ions via inward rectifier potassium channels (I-K1), which allow an outward flow of potassium ions down their concentration gradient. The positive outflow of potassium ions aids in maintaining the negative intracellular electric potential. When cells reach a critical threshold potential, voltage-gated sodium channels (I-Na) open and the rapid influx of positive sodium ions into the cell occurs as the ions travel down their electrochemical gradient. This is known as the rapid depolarization or upstroke phase of the cardiac action potential. Sodium channels then close and rapidly activated potassium channels such as the voltage-gated transient outward delayed rectifying potassium channel (I-Kto) and the voltage-gated ultra rapid delayed rectifying potassium channel (I-Kur) open. These events make up the early repolarization phase during which potassium ions flow out of the cell and sodium ions are continually pumped out. During the next phase, known as the plateau phase, calcium L-type channels (I-CaL) open and the resulting influx of calcium ions roughly balances the outward flow of potassium channels. During the final repolarization phase, the voltage-gated rapid (I-Kr) and slow (I-Ks) delayed rectifying potassium channels open increasing the outflow of potassium ions and repolarizing the cell. The extra sodium and calcium ions that entered the cell during the action potential are extruded via sodium-potassium ATPases and NCX and intra- and extracellular ion concentrations are restored. In specialized pacemaker cells, gradual depolarization to threshold occurs via funny channels (I-f). Fosphenytoin, an antiepileptic drug that exhibits Class 1B antiarrhythmic effects, is a soluble pro-drug phosphate ester. It is rapidly absorbed intramuscularly and rapidly metabolized in the blood stream by plasma esterases to the active drug, phenytoin. Fosphenytoin was developed to replace parenteral phenytoin sodium for the treatment of epileptic seizures. Parenteral phenytoin sodium was originally prepared in 40% propylene glycol and 10% ethanol at pH 12. This formulation exhibited a range of toxic effects from severe irritation and pain at the injection site to occasional death from rapid injections. Although fosphenytoin is used to treat epileptic seizures, antiarrhythmic effects have also been observed. The active metabolite, phenytoin, preferentially binds to sodium channels (I-Na) in their inactive state. This causes a slight delay in the rapid depolarization phase of cardiac myocyte action potentials. In contrast to Class 1A antiarrhythmic drugs (e.g. quinidine) which prolong action potential duration, fosphenytoin and other Class 1B antiarrhythmics reduce the refractory period or action potential duration due to their membrane stabilizing effects. Phenytoin has been found to be beneficial in the treatment of atrial and ventricular arrhythmias.


Felodipine Metabolism Pathway,Drug Metabolism

Felodipine belongs to the dihydropyridine (DHP) class of calcium channel blockers (CCBs), the most widely used class of CCBs.  CCBs target L-type calcium channels, the major channel in muscle cells that mediates contraction.  Similar to other DHP CCBs, felodipine binds directly to inactive calcium channels stabilizing their inactive conformation.  Since arterial smooth muscle depolarizations are longer in duration than cardiac muscle depolarizations, inactive channels are more prevalent in smooth muscle cells.  Alternative splicing of the alpha-1 subunit of the channel gives felodipine additional arterial selectivity.  At therapeutic sub-toxic concentrations, felodipine has little effect on cardiac myocytes and conduction cells.  This pathway depicts the pharmacological action of felodipine on arterial smooth muscle cells.  Felodipine decreases arterial smooth muscle contractility and subsequent vasoconstriction by inhibiting the influx of calcium ions through L-type calcium channels.  Calcium ions entering the cell through these channels bind to calmodulin.  Calcium-bound calmodulin then binds to and activates myosin light chain kinase (MLCK).  Activated MLCK catalyzes the phosphorylation of the regulatory light chain subunit of myosin, a key step in muscle contraction.  Signal amplification is achieved by calcium-induced calcium release from the sarcoplasmic reticulum through ryanodine receptors.  Inhibition of the initial influx of calcium decreases the contractile activity of arterial smooth muscle cells and results in vasodilation.  The vasodilatory effects of felodipine result in an overall decrease in blood pressure.  Felodipine may be used to treat mild to moderate essential hypertension.  .


Lidocaine (Local Anaesthetic) Metabolism Pathway,Drug Metabolism

Lidocaine exerts its local anaesthetic effect by blocking voltage-gated sodium channels in peripheral neurons. Lidocaine diffuses across the neuronal plasma membrane in its uncharged base form. Once inside the cytoplasm, it is protonated and this protonated form enters and blocks the pore of the voltage-gated sodium channel from the cytoplasmic side. For this to happen, the sodium channel must first become active so that so that gating mechanism is in the open state. Therefore lidocaine preferentially inhibits neurons that are actively firing.


Codeine Metabolism Pathway,Drug Metabolism

Opiate receptors are coupled with G-protein receptors and function as both positive and negative regulators of synaptic transmission via G-proteins that activate effector proteins. Binding of the opiate stimulates the exchange of GTP for GDP on the G-protein complex. As the effector system is adenylate cyclase and cAMP located at the inner surface of the plasma membrane, opioids decrease intracellular cAMP by inhibiting adenylate cyclase. Subsequently, the release of nociceptive neurotransmitters such as substance P, GABA, dopamine, acetylcholine and noradrenaline is inhibited. Opioids also inhibit the release of vasopressin, somatostatin, insulin and glucagon. Codeine's analgesic activity is, most likely, due to its conversion to morphine. Opioids close N-type voltage-operated calcium channels (OP2-receptor agonist) and open calcium-dependent inwardly rectifying potassium channels (OP3 and OP1 receptor agonist). This results in hyperpolarization and reduced neuronal excitability.


Morphine Metabolism Pathway,Drug Metabolism

Morphine exerts its analgesic by acting on the mu-opioid receptor of sensory neurons. Binding to the mu-opioid receptor activates associated G(i) proteins. These subsequently act to inhibit adenylate cyclase, reducing the level of intracellular cAMP. G(i) also activates potassium channels and inactivates calcium channels causing the neuron to hyperpolarize. The end result is decreased nerve conduction and reduced neurotransmitter release, which blocks the perception of pain signals.


Heroin Metabolism Pathway,Drug Metabolism

Heroin is a mu-opioid agonist. It acts on endogenous mu-opioid receptors that are spread in discrete packets throughout the brain, spinal cord and gut in almost all mammals. Heroin, along with other opioids, are agonists to four endogenous neurotransmitters. They are beta-endorphin, dynorphin, leu-enkephalin, and met-enkephalin. The body responds to heroin in the brain by reducing (and sometimes stopping) production of the endogenous opioids when heroin is present. Endorphins are regularly released in the brain and nerves, attenuating pain.


Methadone Metabolism Pathway,Drug Metabolism

Methadone exerts its analgesic by acting on the mu-opioid receptor of sensory neurons. Binding to the mu-opioid receptor activates associated G(i) proteins. These subsequently act to inhibit adenylate cyclase, reducing the level of intracellular cAMP. G(i) also activates potassium channels and inactivates calcium channels causing the neuron to hyperpolarize. The end result is decreased nerve conduction and reduced neurotransmitter release, which blocks the perception of pain signals. Methadone further acts as an antagonist at the NMDA receptor, reducting calcium influx and neuronal excitability.


Imipramine Metabolism Pathway,Drug Metabolism

Imipramine is a tricyclic antidepressant that exerts its therapeutic effects by inhibiting norepinephrine and serotonin reuptake in the brain. It does so by competing for the same binding site as norepinephrine on the sodium-dependent noradraneline transporter (SLC6A2) and by competing with serotonin for binding to the sodium-dependent serotonin transporter (SLC6A4). This increases the concentrations of both norepinephrine and serotonin in their respective synapses and reverses the state of low concentrations of both neurotransmitters found in depression. Higher concentrations of norepinephrine and serotonin have also been shown to have long-term neuromodulatory effects. Binding of these neurotransmitters to their respective receptors activate adenylate cyclase, which produces cAMP. cAMP activates protein kinase A which activates cAMP-responsive binding protein 1 (CREB-1). CREB-1 enters the nucleus and affects transcription of brain-derived neurotrophic factor (BDNF). BDNF subsequently stimulates neurogenesis, which may contribute to the long-term reversal of depression.  Imipramine is metabolized in the liver mostly through N-demethylation by CYP2C19 into desipramine. Desipramine is an active metabolite and also has similar actions to imipramine on norepinephrine and serotonin reuptake.


Desipramine Metabolism Pathway,Drug Metabolism

Desipramine is a tricyclic antidepressant that exerts its therapeutic effects by inhibiting norepinephrine and serotonin reuptake in the brain. It does so by competing for the same binding site as norepinephrine on the sodium-dependent noradraneline transporter (SLC6A2) and by competing with serotonin for binding to the sodium-dependent serotonin transporter (SLC6A4). This increases the concentrations of both norepinephrine and serotonin in their respective synapses and reverses the state of low concentrations of both neurotransmitters found in depression. Higher concentrations of norepinephrine and serotonin have also been shown to have long-term neuromodulatory effects. Binding of these neurotransmitters to their respective receptors activate adenylate cyclase, which produces cAMP. cAMP activates protein kinase A which activates cAMP-responsive binding protein 1 (CREB-1). CREB-1 enters the nucleus and affects transcription of brain-derived neurotrophic factor (BDNF). BDNF subsequently stimulates neurogenesis, which may contribute to the long-term reversal of depression.


Citalopram Metabolism Pathway,Drug Metabolism

Citalopram is a selective serotonin reuptake inhibitor that exerts antidepressive effects by selectively inhibiting serotonin reuptake in the brain. It does so by competing for the same binding site as serotonin on the the sodium-dependent serotonin transporter (SLC6A4). This increases the concentrations of serotonin in the synaptic cleft and reverses the state of low concentration seen in depression. Higher concentration of serotonin has also been shown to have long-term neuromodulatory effects. Binding of serotonin to certain serotonin receptors activate adenylate cyclase, which produces cAMP. cAMP activates protein kinase A which activates cAMP-responsive binding protein 1 (CREB-1). CREB-1 enters the nucleus and affects transcription of brain-derived neurotrophic factor (BDNF). BDNF subsequently stimulates neurogenesis, which may contribute to the long-term reversal of depression.


Nicotine Metabolism Pathway,Drug Metabolism

Nicotine is a stimulant drug that acts as an agonist at nicotinic acetylcholine receptors. These are ionotropic receptors composed of five homomeric or heteromeric subunits. In the brain, nicotine binds to nicotinic acetylcholine receptors on dopaminergic neurons in the cortico-limbic pathways. This causes the channel to open and allow conductance of multiple cations including sodium, calcium, and potassium. This leads to depolarization, which activates voltage-gated calcium channels and allows more calcium to enter the axon terminal. Calcium stimulates vesicle trafficking towards the plasma membrane and the release of dopamine into the synapse. Dopamine binding to its receptors is responsible the euphoric and addictive properties of nicotine.Nicotine also binds to nicotinic acetylcholine receptors on the chromaffin cells in the adrenal medulla. Binding opens the ion channel allowing influx of sodium, causing depolarization of the cell, which activates voltage-gated calcium channels. Calcium triggers the release of epinephrine from intracellular vesicles into the bloodstream, which causes vasoconstriction, increased blood pressure, increased heart rate, and increased blood sugar.


Adefovir Dipivoxil Metabolism Pathway,Drug Metabolism

Adefovir dipivoxil is an ester prodrug of adefovir, a nucleotide analogue used in the treatment of chronic hepatitis B. Adefovir dipivoxil is taken up into the liver cell and is cleaved into adefovir by intracellular esterases. Adefovir is subsequently phosphorylated first by adenylate kinases and then by nucleoside diphosphate kinases into adefovir diphosphate. Adefovir diphosphate is an analogue of deoxyadenosine triphosphate (dATP) and competes with dATP for binding to the viral DNA polymerase and subsequent incorporation into the growing DNA strand. Once incorporated into the DNA, adefovir causes chain termination, thus preventing viral replication.


Tenofovir Metabolism Pathway,Drug Metabolism

Tenofovir is a nucleotide analogue used in the treatment of HIV and chronic hepatitis B. It is taken up into the cell and is subsequently phosphorylated first by adenylate kinases and then by nucleoside diphosphate kinases into tenofovir diphosphate. Tenofovir diphosphate is an analogue of deoxyadenosine triphosphate (dATP) and competes with dATP for binding to the viral DNA polymerase and subsequent incorporation into the growing DNA strand. Once incorporated into the DNA, tenofovir causes chain termination, thus preventing viral replication.


Prednisone Metabolism Pathway,Drug Metabolism

Prednisone is a synthetic glucocorticoid that is used clinically for its anti-inflammatory properties. Prednisone is converted to the active metabolite prednisolone in the liver. Prednisolone can diffuse passively across the cell membrane, where it binds to glucocorticoid receptors in the cytoplasm. Upon binding, the glucocorticoid receptor (GR) dissociates from heat shock protein 90, and translocate into the nucleus. In the nucleus, GR dimers can bind to glucocorticoid response element (GRE) in the promoter region of anti-inflammatory genes, which activates their transcription. GRs also inhibit transcription of inflammatory mediators by binding to negative GRE (nGRE). GRs further interact with the transcription factors cAMP-responsive element binding protein and NF-kappa-B, and inihibit their activation of inflammatory gene transcription. GRs also recruit histone deacetylase 2 to inflammatory genes, which leads to DNA condensation at those loci, thus suppressing expression of those genes.


Prednisolone Metabolism Pathway,Drug Metabolism

Prednisolone is a synthetic glucocorticoid that is used clinically for its anti-inflammatory properties. Prednisolone diffuses passively across the cell membrane, where it binds to glucocorticoid receptors in the cytoplasm. Upon binding, the glucocorticoid receptor (GR) dissociates from heat shock protein 90, and translocate into the nucleus. In the nucleus, GR dimers can bind to glucocorticoid response element (GRE) in the promoter region of anti-inflammatory genes, which activates their transcription. GRs also inhibit transcription of inflammatory mediators by binding to negative GRE (nGRE). GRs further interact with the transcription factors cAMP-responsive element binding protein and NF-kappa-B, and inihibit their activation of inflammatory gene transcription. GRs also recruit histone deacetylase 2 to inflammatory gene loci on DNA, which leads to DNA condensation and suppression of gene expression.


Felbamate Metabolism Pathway,Drug Metabolism

Felbamate is metabolized in the liver. One route of metabolism consists of the hydroxylation to 2-hydroxyfelbamate or p-hydroxyfelbamate, which is catalyzed by CYP2E1 and CYP3A4. Moreover, felbamate can be transformed to 2-phenyl-2-propanediol monocarbamate. This metabolite is then converted to 3-carbamoyl-2phenylpropionaldehyde via alchol dehydrogenase 1A, which in turn can be transformed into three possible metabolites: atropaldehyde, 3-carbamoyl-2-phenylpropionic acid (catalyzed by the dimeric NADP-preferring aldehyde dehydrogenase), and 4-hydroxy-5-phenyltetrahydro-1,3-oxazin-2-one. The latter is further converted by the alcohol dehydrogenase 1A to 5-phenyl-1,3-oxazinane-2,4-dione, which is subsequently transformed to 3-carbamoyl-2-phenylpropionic acid.


Carbamazepine Metabolism Pathway,Drug Metabolism

Carbamazepine is a drug used in the treatment of epilepsy, bipolar disorder, trigeminal neuralgia, and other psychiatric disorders. Carbamazepine is almost entirely metabolized in the liver, with the primary metabolic pathway being conversion to 10,11-epoxycarbamazepine. Ring hydroxylation to 2-hydroxycarbamazepine and 3-hydroxycarbamazepine represent a minor metabolic route, presumably though a carbamazepine 2,3-epoxide intermediate. Potential bioactivation occurs via CYP3A4-mediated secondary oxidation of 2-hydroxycarbamazepine to the potentially reactive carbamazepine iminoquinone and of 3-hydroxycarbamazepine to form other reactive metabolites. Radicals can also be formed from metabolism of 3-hydroxycarbamazepine by myeloperoxidase. Oxcarbazepine, an anticonvulsant used primarily in the treatment of epilepsy, is converted to 10,11-dihydroxycarbamazepine via 10-hydroxycarbazepine.


Valproic Acid Metabolism Pathway,Drug Metabolism

Valproic acid (VPA) is metabolized almost entirely in the liver, via at least there routes: glucuronidation, beta oxidation in the mitochondria, and cytochrome P450 mediated oxidation. The glucuronidation of VPA is mediated by UGT1A3, UGT1A4, UGT1A6, UGT1A8, UGT1A9, UGT1A10, UGT2B7 and UGT2B15. The key CYP-mediated reaction of the VPA metabolic pathway is the generation of 4-ene-VPA by CYP2C9, CYP2A6 and CYP2B6. These three enzymes also catalyze the formation of 4-OH-VPA and 5-OH-VPA. Moreover, CYP2A6 mediates the oxidation of VPA to 3-OH-VPA. Inside the mitochondria, the first step of oxidation is the formation of (VPA-CoA) catalyzed by medium-chain acyl-CoA synthase, followed by the conversion to 2-ene-VPA-CoA through 2-methyl-branched chain acyl-CoA dehydrogenase (ACADSB). 2-ene-VPA-CoA is further converted to 3-hydroxyl-valproyl-VPA (3-OH-VPA-CoA) by an enoyl-CoA hydratase, crotonase (ECSH1) and then 3-OH-VPA-CoA is metabolized to 3-keto-valproyl-CoA (3-oxo-VPA-CoA) through the action of 2-methyl-3-hydroxybutyryl-CoA dehydrogenase. Another route of VPA metabolism in the mitochondria includes the conversion of 4-ene-VPA to 4-ene-VPA-CoA ester catalyzed by ACADSB, followed by a beta-oxidation to form 2,4-diene-VPA-CoA ester. The latter metabolite can furthermore be conjugated to glutathione to form thiol metabolites.


Venlafaxine Metabolism Pathway,Drug Metabolism

Venlafaxine (also named as Effexor or Elafax) is an antidepressant medication, which belongs to the class of serotonin-norepinephrine reuptake inhibitor (SNRI). Venlafaxine is well absorbed into the circulation system. Venlafaxine is also metabolized to N-desmethylvenlafaxine. The N-demethylation is catalyzed by CYP3A4 and CYP2C19. N-desmethylvenlafaxine is a weaker serotonin and norepinephrine reuptake inhibitor. Both O-desmethylvenlafaxine (as potent a serotonin-norepinephrine reuptake inhibitor) and N-desmethylvenlafaxine are further metabolized by CYP2C19, CYP2D6 and/or CYP3A4 to a minor metabolite N,O-didesmethylvenlafaxine that is further metabolized into N,N,O-tridesmethylvenlafaxine or excreted as N,O-didesmethylvenlafaxine gucuronide. Later on, O-desmethylvenlafaxine is exported without any change in chemical structure. Venlafaxine is exported via two transporters: Multidrug resistance protein 1 and ATP-binding cassette sub-family G member 2.


Tramadol Metabolism Pathway,Drug Metabolism

Tramadol (also named Ultram) is a class of opioid pain medication that used for treating pain. Metabolism of tramadol mainly happened in liver cell. The N-demethylation of tramadol is catalyzed by the cytochrome CYP3A4 and CYP2B6 to form N-Desmethyltramadol, which further metabolized to N,N-Didesmethyltramadol through CYP3A4 and CYP2B6 and to N,O-Didesmethyltramadol through CYP2D6. The O-demethylation of tramadol is catalyzed by the cytochrome CYP2D6 to form O-Desmethyltramadol, which further metabolized to O-Desmethyltramadol glucuronide through UDP-glucuronosyltransferase 2B7 and UDP-glucuronosyltransferase 1-8. O-Desmethyltramadol can also be metabolized to N,O-Didesmethyltramadol through CYP2D6.


Levomethadyl Acetate Metabolism Pathway,Drug Metabolism

Levomethadyl Acetate (also known as levacetylmethadol or levo-α-acetylmethadol) (LAAM), is a synthetic opioid structurally similar to methadone. It is an opioid agonist that has been used as an analgesic and to treat opioid dependence. Levomethadyl Acetate is metabolized by cytochrome P450 3A4 in two N-demethylation reactions to nor-levomethadyl acetate (nor-LAAM) and subsequently to dinor-levomethadyl acetate (dinor-LAAM).


Clomipramine Metabolism Pathway,Drug Metabolism

Clomipramine is a dibenzazepine-derivative tricyclic antidepressant. Clomipramine may be used to treat obsessive-compulsive disorder and disorders with an obsessive-compulsive component (e.g. depression, schizophrenia, Tourette's disorder).


Acetaminophen Metabolism Pathway,Drug Metabolism

Acetaminophen (APAP) is metabolized primarily in the liver. Glucuronidation is the main route, accounting for 45-55% of APAP metabolism, and is mediatied by UGT1A1, UGT1A6, UGT1A9, UGT2B15 in the liver and UGT1A10 in the gut. APAP can also by metabolized via sulfation, accounting for 30-35% of the metabolism. In the liver, this step is catalyzed by the sulfotransferases SULT1A1, SULT1A3, SULT1A4, SULT1E1 and SULT2A1. Moreover, APAP can also be activated to form the toxic N-acetyl-p-benzoquinone imine (NAPQI) under the mediation of CYP3A4, CYP2E1, CYP2D6 CYP1A2, CYP2E1 and CYP2A6.


Doxepin Metabolism Pathway,Drug Metabolism

Doxepin is a tricyclic antidepressant (TCA) that can be used for treating major depressive disorder, sleep maintenance. Doxepin is metabolized by cytochrome P450 2C19, 1A2, 2C9, 3A4 to form N-desmethyldoxepin, and form (E)-2-hydroxydoxepin by solely cytochrome P450 2D6 in ER of liver.


Nevirapine Metabolism Pathway,Drug Metabolism

Nevirapine is used in the treatment of human immunodeficiency virus (HIV) type 1 (HIV-1) infection. It is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that binds to the tyrosines at amino acid residues 181 and 188 of HIV-1 reverse transcriptase. Nevirapine is metabolized in the liver to 2-, 3-, 8-, and 12-hydroxynevirapine by the induction of CYP enzymes, mainly CYP3A4 and CYP2B6. 12-hydroxynevirapine may be further oxidated by ALDH to form 4-carboxynevirapine. These hydroxyl metabolites are glucuronidated by UDP glucuronosyl transferases (UGTs), then exit the cell via the adenosine triphosphate-binding cassette gene ABCC10 for urinary excretion.


Celecoxib Metabolism Pathway,Drug Metabolism

Celecoxib, a non-steroidal anti-inflammatory drug (NSAID), is a selective inhibitor of cyclooxygenase-2 (COX-2), also known as prostaglandin G/H synthase 2. Like other NSAIDs, celecoxib exerts its effects by inhibiting the synthesis of prostaglandins involved in pain, fever and inflammation. COX-2 catalyzes the conversion of arachidonic acid to prostaglandin G2 (PGE2) and PGE2 to prostaglandin H2 (PGH2). In the COX-2 catalyzed pathway, PGH2 is the precusor of prostaglandin E2 (PGE2) and I2 (PGI2). PGE2 induces pain, fever, erythema and edema. Celecoxib antagonizes COX-2 by binding to the upper portion of the active site, preventing its substrate, arachidonic acid, from entering the active site. Similar to other COX-2 inhibitors, such as rofecoxib and valdecoxib, celecoxib appears to exploit slight differences in the size of the COX-1 and -2 binding pockets to gain selectivity. COX-1 contains isoleucines at positions 434 and 523, whereas COX-2 has slightly smaller valines occupying these positions. Studies support the notion that the extra methylene on the isoleucine side chains in COX-1 adds enough bulk to proclude celecoxib from binding. Celecoxib is approximately ten times more selective for COX-2 than COX-1. Celecoxib is used mainly to treat rheumatoid arthritis and osteoarthritis which require something more potent than aspirin. The analgesic, antipyretic and anti-inflammatory effects of celecoxib occur as a result of decreased prostaglandin synthesis.  The first part of this figure depicts the anti-inflammatory, analgesic and antipyretic pathway of celecoxib. The latter portion of this figure depicts celecoxib’s potential involvement in platelet aggregation. Prostaglandin synthesis varies across different tissue types. Platelets, which are anuclear cells derived from fragmentation of megakaryocytes, contain COX-1, but not COX-2. COX-1 activity in platelets is required for thromboxane A2 (TxA2)-mediated platelet aggregation. Platelet activation and coagulation do not normally occur in intact blood vessels. After blood vessel injury, platelets adhere to the subendothelial collagen at the site of injury. Activation of collagen receptors initiates phospholipase C (PLC)-mediated signaling cascades resulting in the release of intracellular calcium from the dense tubula system. The increase in intracellular calcium activates kinases required for morphological change, transition to the procoagulant surface, secretion of granular contents, activation of glycoproteins, and the activation of phospholipase A2 (PLA2). Activation of PLA2 results in the liberation of arachidonic acid, a precursor to prostaglandin synthesis, from membrane phospholipids. The accumulation of TxA2, ADP and thrombin mediates further platelet recruitment and signal amplification. TxA2 and ADP stimulate their respective G-protein coupled receptors, thomboxane A2 receptor and P2Y purinoreceptor 12, and inhibit the production of cAMP via adenylate cyclase inhibition. This counteracts the adenylate cyclase stimulatory effects of the platelet aggregation inhibitor, PGI2, produced by neighbouring endothelial cells. Platelet adhesion, cytoskeletal remodeling, granular secretion and signal amplification are independent processes that lead to the activation of the fibrinogen receptor. Fibrinogen receptor activation exposes fibrinogen binding sites and allows platelet cross-linking and aggregation to occur. Neighbouring endothelial cells found in blood vessels express both COX-1 and COX-2. COX-2 in endothelial cells mediates the synthesis of PGI2, an effective platelet aggregation inhibitor and vasodilator, while COX-1 mediates vasoconstriction and stimulates platelet aggregation. PGI2 produced by endothelial cells encounters platelets in the blood stream and binds to the G-protein coupled prostacyclin receptor. This causes G-protein mediated activation of adenylate cyclase, which catalyzes the conversion of adenosine triphosphate (ATP) to cyclic AMP (cAMP). Four cAMP molecules then bind to the regulatory subunits of the inactive cAMP-dependent protein kinase holoenzyme causing dissociation of the regulatory subunits and leaving two active catalytic subunit monomers. The active subunits of cAMP-dependent protein kinase catalyze the phosphorylation of a number of proteins. Phosphorylation of inositol 1,4,5-trisphosphate receptor type 1 on the endoplasmic reticulum (ER) inhibits the release of calcium from the ER. This in turn inhibits the calcium-dependent events, including PLA2 activation, involved in platelet activation and aggregation. Inhibition of PLA2 decreases intracellular TxA2 and inhibits the platelet aggregation pathway. cAMP-dependent kinase also phosphorylates the actin-associated protein, vasodilator-stimulated phosphoprotein. Phosphorylation inhibits protein activity, which includes cytoskeleton reorganization and platelet activation. Celecoxib preferentially inhibits COX-2 with little activity against COX-1. COX-2 inhibition in endothelial cells decreases the production of PGI2 and the ability of these cells to inhibit platelet aggregation and stimulate vasodilation. These effects are thought to be responsible for the adverse cardiovascular effects observed with other selective COX-2 inhibitors, such as rofecoxib, which has since been withdrawn from the market.


Azathioprine Metabolism Pathway,Drug Metabolism

Azathioprine is a purine antimetabolite prodrug that exerts cytotoxic effects via three mechanisms: via incorporation of thiodeoxyguanosine triphosphate into DNA and thioguanosine triphosphate into RNA, inhibition of de novo synthesis of purine nucleotides, and inhibition of Ras-related C3 botulinum toxin substrate 1, which induces apoptosis of activated T cells. Azathioprine is first converted _in vivo_ to mercaptopurine in the liver. Mercaptopurine then travels through the bloodstream and is transported into cells via nucleoside transporters.  Mercaptopurine is converted to thioguanosince diphosphate through a series of metabolic reactions that produces the metabolic intermediates, thioinosine 5’-monophosphate, thioxanthine monophosphate, and thioguanosine monophosphate. Thioguanosine diphosphate is then converted via a thiodeoxyguanosine diphosphate intermediate to thiodeoxyguanosine triphosphate, which is incorporated into DNA. Thioguanosine diphosphate is also converted to thioguanosine triphosphate which is incorporated into RNA. The thioguanosine triphosphate metabolite also inhibits Ras-related C3 botulinum toxin substrate 1, a plasma membrane-associated small GTPase that regulates cellular processes, inducing apoptosis in activated T cells. Finally, de novo synthesis of purine nucleotides is inhibited by the methyl-thioinosine 5’-monophosphate metabolite, which inhibits amidophosphoribosyl-transferase, the enzyme that catalyzes one of the first steps in this pathway.


Fluoxetine Metabolism Pathway,Drug Metabolism

Fluoxetine is a selective serotonin reuptake inhibitor that exerts antidepressive effects by selectively inhibiting serotonin reuptake in the brain. It does so by competing for the same binding site as serotonin on the the sodium-dependent serotonin transporter (SLC6A4). This increases the concentrations of serotonin in the synaptic cleft and reverses the state of low concentration seen in depression. Higher concentration of serotonin has also been shown to have long-term neuromodulatory effects. Binding of serotonin to certain serotonin receptors activate adenylate cyclase, which produces cAMP. cAMP activates protein kinase A which activates cAMP-responsive binding protein 1 (CREB-1). CREB-1 enters the nucleus and affects transcription of brain-derived neurotrophic factor (BDNF). BDNF subsequently stimulates neurogenesis, which may contribute to the long-term reversal of depression.


Thioguanine Metabolism Pathway,Drug Metabolism

Thioguanine is a purine antimetabolite prodrug closely related to mercaptopurine and similarly inhibits purine metabolism. The thioguanine pathway is shown as a part of the mercaptopurine pathway. Thioguanine exerts cytotoxic effects via incorporation of thiodeoxyguanosine triphosphate into DNA and thioguanosine triphosphate into RNA and inhibition of Ras-related C3 botulinum toxin substrate 1, which induces apoptosis of activated T cells. Once in a cell, thioguanine is converted to thioguanosine monophosphate by hypoxanthine-guanine phosphoribosyltransferase. Thioguanosine monophosphate is then phosphorylated to thioguanosine diphosphate, which is converted via a thiodeoxyguanosine diphosphate intermediate to thiodeoxyguanosine triphosphate. Thiodeoxyguanosine triphosphate is incorporated into DNA causing cytotoxicity. Thioguanosine diphosphate is also converted to thioguanosine triphosphate which is incorporated into RNA. The thioguanosine triphosphate metabolite also inhibits Ras-related C3 botulinum toxin substrate 1, a plasma membrane-associated small GTPase that regulates cellular processes, inducing apoptosis in activated T cells.


Sorafenib Metabolism Pathway,Drug Metabolism

Sorafenib is a drug that belongs to the antineoplastics drug class, which is the drug class relating to the treatment of cancer, specifically renal, hepatic and thyroid cancers. This drug works by stopping cancerous tumour progress and stopping therapy replication pf potentially malignant cells. It does this by inhibiting protein synthesis, as we will explore in the pathway. Sorafenib is administered orally, in a tablet form taken twice daily without food. Once ingested, sorafenib finds itself in the endoplasmic reticulum membrane , where it inhibits cytochrome P450 2B6, cytochrome P450 2C8, cytochrome P450 2C9 and UDP-glucuronosyltransferase 1-1. Sorafenib is also catalyzed, with the help uridine diphosphate glucuronic acid and the enzyme UDP-glucuronosyltransferase 1-9 to sorafenib b-D-glucuronide with a by-product of uridine 5’-diphosphate. Sorafenib also undergoes a transformation without the use of catalytic enzymes and becomes sorafenib metabolite M4 and subsequently becomes sorafenib metabolite M5. In another reaction, sorafenib teams up with water and oxygen, using cytochrome P450 3A4 to create sorafenib N-oxide and hydrogen peroxide. Sorafenib N-oxide then undergoes two more reactions, one where it becomes sorafenib N-oxide glucuronide, and another where it becomes sorafenib metabolite M1. Sorafenib metabolite M1 is also attached to another reaction, as sorafenib creates sorafenib metabolite M3, sorafenib metabolite M1 is also created from this metabolite.


Lamivudine Metabolism Pathway,Drug Metabolism

Lamivudine (2'-deoxy-3'-thiacytidine, 3TC) is a pyrimidine analog reverse transcriptase enzyme inhibitor used to treat human immunodeficiency virus type I (HIV-1), HIV-2, and Hepatitis B. When metabolized to its active triphosphate form, it competes with deoxycytidine triphosphate for binding to reverse transcriptase, resulting in chain termination when incorporated into the viral DNA. Lamivudine may enter the cells by passive diffusion or by active transported via SLC22A1, SLC22A2, and SLC22A3. Intracellularly, it is phosphorylated to its active triphosphate from via deoxycytidine kinase (3TC to 3TC-monophosphate), followed by cytidine monophosphate/deoxycytidine monophosphate kinase (3TC-monophosphate to 3TC-diphosphate), then 3'-phosphoglycerate kinase or nucleoside diphosphate kinase (3TC-diphosphate to 3TC-triphosphate). Dephosphorylation can occur via phosphatases or salvage pathways. Lamivudine is actively transported out of cell by efflux transporters ABCB1, ABCC1, ABCC2, ABCC3, ABCC4 and ABCG2 and primarily excreted unchanged in the urine.


Doxorubicin Metabolism Pathway,Drug Metabolism

Doxorubicin is an anthracycline antibiotic used as a cancer chemotherapy drug. The major metabolic route of doxorubicin metabolism is two-electron reduction to doxorubicinol. A second route is one-electron reduction resulting in a doxorubicin-semiquinone, which can be undertaken by NADH dehydrogenases in the sarcoplasmic reticulum or mitochondrion, or nitric oxide synthases, NADPH dehydrogenase, or xanthine oxidase. Reactive oxygen species are formed when the semiquinone is re-oxidized back to doxorubicin. The reactive oxygen species are thought by some to be responsible for the drug's effects and cardiotoxicity, and can be deactivated by glutathione peroxidase, catalase, and superoxide dismutase. A third and minor metabolic route involves deglycosidation and results in the formation of doxirubicinol hydroxyaglycone. Approximately 50% of doxorubicin is eliminated unchanged from the body.


Artemether Metabolism Pathway,Drug Metabolism

Artemether is a semisynthetic derivative of artemisinin, a phytoconstituent that acts as a short-acting antimalarial agent and is used to treat uncomplicated Plasmodium falciparum malaria. Artemisinin derivatives kill parasites more rapidly than conventional antimalarial drugs, and are active against both the sexual and asexual stages of the parasite cycle. However due to their short half-life (and to prevent resistance development) artemisinin compounds are often combined with long-acting antimalarial drugs. Artemeter is administered orally and as an oil-based intramuscular injection. The antimalarial activity of artemether and other artemisinin derivatives is a result of the peroxide bridge found in the active metabolite dihydroartemisinin. Dihydroartemisinin is formed from the rapid demethylation of artmether via CYP3A4 and CYP3A5. It then undergoes glucuronidation catalyzed by the UDP-glucuronosyltransferases UGT1A9 and UGT2B7 into inactive metabolites that are eliminated in the bile.


Mycophenolic Acid Metabolism Pathway,Drug Metabolism

Mycophenolic Acid (MPA) is an immunosuppressive agent that acts as a noncompetitive, selective and reversible inhibitor of inosine monophosphate dehydrogenase (IMPDH). It is available as a prodrug, Mycophenolate mofetil (MMF), which is a 2-morpholinoethyl ester with improved bioavailability. After absorption, MMF is hydrolyzed to MPA and N-(2-carboxymethyl)- morpholine, N-(2-hydroxyethyl)-morpholine, and the N-oxide of N-(2-hydroxyethyl)-morpholine by the carboxylesterases CES-1 (in the liver only) and CES-2 (in the liver and intestine). The morpholine metabolites are excreted in the urine. MPA is glucuronidated by UDP glucuronosyl transferases (UGTs) UGT1A7, UGT1A8, UGT1A9 and UGT1A10 to MPA-7-O-glucuronide, which is excreted in the urine. Other metabolites of MPA include MPA-acyl glucoronide, which is formed by UGT2B7, and 6-O-desmethyl-MPA, which is formed by the CYP enzymes CYP3A4, CYP3A5 and CYP2C8. MPA enters hepatocytes by the organic anion transport proteins (OATPs) SLCO1B1 and SLCO1B3. MPA and its metabolites are excreted in the bile via the ABCC2, ABCG2, and ABCB1 proteins.


Rosiglitazone Metabolism Pathway,Drug Metabolism

Rosiglitazone is an anti-diabetic drug in the thiazolidinedione class of drugs. It is extensively metabolized in the liver by the cytochrome p450 enzymes CYP2C8 and CYP2C9 to para-hydroxy rosiglitazon, ortho-hydroxy rosiglitazone and N-desmethyl rosiglitazone. N-desmethyl rosiglitazone is the major metabolite and is further metabolized to N-desmethyl-p-hydroxyrosiglitazone, N-desmethyl glucuronide rosiglitazone and N-desmethyl-O-hydroxy rosiglitazone. Both para-hydroxy rosiglitazon and ortho-hydroxy rosiglitazone are excreted as sulfated or glucuronidated metabolites.