title: Diazepam effects and kinetics in Caucasians and Orientals.
abstract: Mental and psychomotor effects and diazepam kinetics were studied in Caucasian and Orientals. 12 Caucasian and 13 Oriental young adults received on one of two occasions, separated by 2 weeks, either 0.2-mg/kg diazepam or saline intravenously. Serum diazepam and desmethyldiazepam concentrations were measured by electron-capture gas-liquid chromatography in samples drawn up to 72 hr after injection. Serum protein binding was measured by equilibrium dialysis. Subjects were tested on a battery of psychological tests before and 0.5, 2, and 4 hr after treatment. While the free fraction of diazepam was identical in both races (0.02), volume of distribution at steady state (Vdss) was different when calculated as absolute volume (Vdss = 76.55 +/- 9.63 l in Caucasians and 54.96 +/- 4.55 l in Orientals, p = 0.04) and marginally significant when corrected for body weight (Vdssl/kg = 1.10 +/- 0.11 in Caucasian and 0.88 +/- 0.05 in Orientals, p = 0.07). total body clearance (Cl), but not elimination half-life (t 1/2), was higher in Caucasians than Orientals, p less than 0.01; t 1/2 = 37.70 +2- 5.53 hr in Caucasians and 41.77 +/- 3.80 in Orientals). Desmethyldiazepam levels were higher in Orientals than Caucasians. Mental and psychomotor effects were maximal at the first session (0.5 hr), followed by complete recovery by the 4-hr session. Effects were similar in both groups. If repeated dosing causes a higher rate of cumulated diazepam serum levels in Orientals, as expected, there might be deeper brain depression in that group.
mesh_terms: D000328:Adult; D044466:Asian People; D003975:Diazepam / Q000378:metabolism* / Q000494:pharmacology; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008568:Memory / Q000187:drug effects; D008657:Metabolic Clearance Rate; D044465:White People
chemical_list: D003975:Diazepam