Cytochrome P450 2A6 Phenotyping Using Dietary Caffeine Salivary Metabolite Ratios and Genotyping Using Blood on Storage Cards in Non-smoking Japanese Volunteers

Background: A simple method of genotyping and phenotyping cytochrome P450 2A6 (CYP2A6) was previously reported using individual blood samples and urinary caffeine metabolite ratios of 1,7-dimethyluric acid (17U) to 1-methylxanthine (1X). Objective: Blood spotted onto storage cards and salivary caffeine metabolites were analyzed in 27 healthy non-smoking Japanese volunteers with no prior abstention from dietary caffeine intake. Methods: 1,7-Dimethylxanthine (17X), 17U, 1X, and caffeine levels in spot saliva samples were determined in Japanese non-smokers by high-performance liquid chromatography under normal dietary caffeine consumption. Results: 17U/17X ratios in saliva were almost constant over time, but those of 17U/1X were variable in two subjects tested before and 1-2.5 h after caffeine treatment (a cup of black tea). In seven subjects, 17U/17X ratios in saliva were highly correlated with those in plasma (r = 0.98, p
Source: Drug Metabolism Letters - Category: Drugs & Pharmacology Source Type: research