Effects of terfenadine and diphenhydramine on the CYP2D6 activity in healthy volunteers.
Article Details
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Kortunay S, Bozkurt A, Basci NE, Kayaalp SO
Effects of terfenadine and diphenhydramine on the CYP2D6 activity in healthy volunteers.
Eur J Drug Metab Pharmacokinet. 2002 Jul-Sep;27(3):171-4. doi: 10.1007/BF03190453.
- PubMed ID
- 12365197 [ View in PubMed]
- Abstract
The aim of this study was to investigate the effects of two antihistaminic drugs, terfenadine and diphenhydramine on CYP2D6 activity by using debrisoquine as a model substrate. The study was carried out as an in vivo single-dose study in 12 young, healthy men. All volunteers had previously been identified as debrisoquine-extensive metabolizers. The volunteers took increasing single oral doses of one of the two antihistaminic drugs in randomized order, at weekly intervals, followed 1 h later by debrisoquine test. Terfenadine and diphenhydramine were given in the doses of 60 and 120 mg; 100 and 150 mg, respectively. The 8-hr urinary concentrations of debrisoquine and 4-hydroxydebrisoquine were determined by high-performance liquid chromatography (HPLC). With increasing doses of terfenadine and diphenhydramine, there was no statistically significant increase in the debrisoquine metabolic ratios (P > 0.05, Page's test for trend). The difference between the median debrisoquine metabolic ratios before and after treatments with terfenadine or diphenhydramine were not statistically significant (Wilcoxon's test). This investigation indicates that single-dose administration of diphenhydramine or terfenadine has no effect on the CYP2D6-mediated hydroxylation of debrisoquine in healthy volunteers.
DrugBank Data that Cites this Article
- Drug Enzymes
Drug Enzyme Kind Organism Pharmacological Action Actions Terfenadine Cytochrome P450 2D6 Protein Humans UnknownSubstrateInhibitorDetails