Biomaterial Database

Normal metabolism of debrisoquine and theophylline in a slow tolbutamide metaboliser. 1985

J O Miners, and L M Wing, and D J Birkett

The metabolism of debrisoquine and theophylline has been studied in a healthy male who was identified as a slow hydroxylator of tolbutamide. Tolbutamide clearance in this subject was three-fold lower than the lowest tolbutamide clearance observed in other healthy males and the drug's half-life was approximately three-fold longer. Despite this, his ability to 4-hydroxylate debrisoquine and both N-demethylate and 8-hydroxylate theophylline was normal. Along with previously published information the data from this subject suggest that tolbutamide hydroxylation, debrisoquine hydroxylation, theophylline N-demethylation, and theophylline 8-hydroxylation involve four distinct isozymes of cytochrome P-450. Furthermore, this report illustrates the difficulties of using the metabolic clearance of a model drug to predict the ability of an individual to clear a range of metabolised drugs.

UI	MeSH Term	Description	Entries
D007527	Isoenzymes	Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics.	Alloenzyme,Allozyme,Isoenzyme,Isozyme,Isozymes,Alloenzymes,Allozymes
D007546	Isoquinolines	A group of compounds with the heterocyclic ring structure of benzo(c)pyridine. The ring structure is characteristic of the group of opium alkaloids such as papaverine. (From Stedman, 25th ed)
D008297	Male		Males
D002851	Chromatography, High Pressure Liquid	Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.	Chromatography, High Performance Liquid,Chromatography, High Speed Liquid,Chromatography, Liquid, High Pressure,HPLC,High Performance Liquid Chromatography,High-Performance Liquid Chromatography,UPLC,Ultra Performance Liquid Chromatography,Chromatography, High-Performance Liquid,High-Performance Liquid Chromatographies,Liquid Chromatography, High-Performance
D003577	Cytochrome P-450 Enzyme System	A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism.	Cytochrome P-450,Cytochrome P-450 Enzyme,Cytochrome P-450-Dependent Monooxygenase,P-450 Enzyme,P450 Enzyme,CYP450 Family,CYP450 Superfamily,Cytochrome P-450 Enzymes,Cytochrome P-450 Families,Cytochrome P-450 Monooxygenase,Cytochrome P-450 Oxygenase,Cytochrome P-450 Superfamily,Cytochrome P450,Cytochrome P450 Superfamily,Cytochrome p450 Families,P-450 Enzymes,P450 Enzymes,Cytochrome P 450,Cytochrome P 450 Dependent Monooxygenase,Cytochrome P 450 Enzyme,Cytochrome P 450 Enzyme System,Cytochrome P 450 Enzymes,Cytochrome P 450 Families,Cytochrome P 450 Monooxygenase,Cytochrome P 450 Oxygenase,Cytochrome P 450 Superfamily,Enzyme, Cytochrome P-450,Enzyme, P-450,Enzyme, P450,Enzymes, Cytochrome P-450,Enzymes, P-450,Enzymes, P450,Monooxygenase, Cytochrome P-450,Monooxygenase, Cytochrome P-450-Dependent,P 450 Enzyme,P 450 Enzymes,P-450 Enzyme, Cytochrome,P-450 Enzymes, Cytochrome,Superfamily, CYP450,Superfamily, Cytochrome P-450,Superfamily, Cytochrome P450
D003647	Debrisoquin	An adrenergic neuron-blocking drug similar in effects to GUANETHIDINE. It is also noteworthy in being a substrate for a polymorphic cytochrome P-450 enzyme. Persons with certain isoforms of this enzyme are unable to properly metabolize this and many other clinically important drugs. They are commonly referred to as having a debrisoquin 4-hydroxylase polymorphism.	Debrisoquine,Tendor
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006900	Hydroxylation	Placing of a hydroxyl group on a compound in a position where one did not exist before. (Stedman, 26th ed)	Hydroxylations
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D013806	Theophylline	A methyl xanthine derivative from tea with diuretic, smooth muscle relaxant, bronchial dilation, cardiac and central nervous system stimulant activities. Theophylline inhibits the 3',5'-CYCLIC NUCLEOTIDE PHOSPHODIESTERASE that degrades CYCLIC AMP thus potentiates the actions of agents that act through ADENYLYL CYCLASES and cyclic AMP.	1,3-Dimethylxanthine,3,7-Dihydro-1,3-dimethyl-1H-purine-2,6-dione,Accurbron,Aerobin,Aerolate,Afonilum Retard,Aquaphyllin,Armophylline,Bronchoparat,Bronkodyl,Constant-T,Elixophyllin,Euphylong,Glycine Theophyllinate,Lodrane,Monospan,Nuelin,Nuelin S.A.,Quibron T-SR,Slo-Phyllin,Somophyllin-T,Sustaire,Synophylate,Theo Von Ct,Theo-24,Theo-Dur,Theobid,Theocin,Theoconfin Continuous,Theodur,Theolair,Theolix,Theon,Theonite,Theopek,Theophylline Anhydrous,Theophylline Sodium Glycinate,Theospan,Theostat,Theovent,Uniphyl,Uniphyllin,Uniphylline,1,3 Dimethylxanthine,Anhydrous, Theophylline,Constant T,ConstantT,Ct, Theo Von,Glycinate, Theophylline Sodium,Quibron T SR,Quibron TSR,Slo Phyllin,SloPhyllin,Sodium Glycinate, Theophylline,Somophyllin T,SomophyllinT,Theo 24,Theo Dur,Theo24,Theophyllinate, Glycine,Von Ct, Theo