In vitro metabolism of quazepam in human liver and intestine and assessment of drug interactions.
Article Details
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Miura M, Ohkubo T
In vitro metabolism of quazepam in human liver and intestine and assessment of drug interactions.
Xenobiotica. 2004 Nov-Dec;34(11-12):1001-11.
- PubMed ID
- 15801544 [ View in PubMed]
- Abstract
The study was carried out to identify and characterize kinetically the cytochrome P450 (CYP) enzymes responsible for the major metabolite formation of quazepam. In in vitro studies using human liver and intestinal microsomes and cDNA-expressed human CYP and FMO isoenzymes, quazepam was rapidly metabolized mainly by CYP3A4 and to a minor extent by CYP2C9, CYP2C19 and FMO1 to 2-oxoquazepam (OQ), which was then further biotransformed to N-desalkyl-2-oxoquazepam (DOQ) and to 3-hydroxy-2-oxoquazepam (HOQ) mainly by CYP3A4 and CYP2C9. CYP3A4 is the enzyme predominantly responsible for all the metabolic pathways of quazepam. Itraconazole inhibited the formation of OQ from quazepam, HOQ from OQ and DOQ from OQ in human liver microsomes with Ki values of 8.40, 0.08 and 0.39 microM, respectively. However, the Ki for OQ formation was greater than the peak plasma itraconazole concentration following a clinically relevant 200-mg oral dose to healthy volunteers. In addition, CYP2C9 and CYP2C19 inhibitors failed to inhibit OQ formation from quazepam. In conclusion, clinically relevant drug interaction with CYP inhibitors seem unlikely for the major metabolic pathway of quazepam to OQ.
DrugBank Data that Cites this Article
- Drugs
- Drug Enzymes
Drug Enzyme Kind Organism Pharmacological Action Actions Quazepam Cytochrome P450 2C19 Protein Humans NoSubstrateDetails Quazepam Cytochrome P450 3A4 Protein Humans NoSubstrateDetails - Drug Reactions
Reaction Details