phase 1 drug metabolizing enzyme
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Introduction
Phase 1 enzymes in general act to make xenobiotics more polar so that they may be eliminated in the urine with or without addition action of phase 2 enzymes.*
Phase 1 enzymes include:
The products of phase 1 enzymes may be cytotoxic &/or carcinogenic.
* lipophilic drugs that pass through the renal glomerulus are reabsorbed by tubular membranes
The cyt P450s are a family of enzymes responsible for most phase 1 enzyme activity. The proportion of drugs metabolized by the major P450s are (roughly):
- cyt P450 3A* 54% (see cyt P450 3A4)
- cyt P450 2D6 24%
- cyt P450 2C 18%
- cyt P450 1A2 2%
- cyt P450 2E1 1%
* drug metabolism is best exemplified by cytochrome P450 3A4
More general terms
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Additional terms
References
- ↑ Nguyen T et al, Ann Rev Pharmacol Toxicol 43:233, 2003
- ↑ The Pharmacological Basis of Therapeutics, 8th ed. Gilman et al, eds. Permagon Press/McGraw Hill pg 11,14
- ↑ Cytochrome P-450 Drug Interactions Prescriber's Letter 6(4):41 1999 Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=150400&pb=PRL (subscription needed) http://www.prescribersletter.com