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Effect of the UGT2B15 Genotype on the Pharmacokinetics, Pharmacodynamics, and Drug Interactions of Intravenous Lorazepam in Healthy Volunteers
Author(s) -
Chung JaeYong,
Cho JooYoun,
Yu KyungSang,
Kim JungRyul,
Jung HyeRyung,
Lim KyoungSoo,
Jang InJin,
Shin SangGoo
Publication year - 2005
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1016/j.clpt.2005.02.006
Subject(s) - lorazepam , pharmacokinetics , pharmacodynamics , pharmacology , medicine , confidence interval , anesthesia , visual analogue scale
Objective Our objective was to investigate the effect of the uridine 5′‐diphosphate‐glucuronosyltransferase (UGT) 2B15 genetic polymorphism on the pharmacokinetics and pharmacodynamics of lorazepam in basal, inhibited, and induced metabolic states in healthy normal volunteers. Methods Twenty‐four healthy subjects were enrolled and grouped into UGT2B15*1/*1 or UGT2B15*2/*2 genotype groups. The pharmacokinetic and pharmacodynamic profiles of intravenous lorazepam were characterized before and after inhibition with 600 mg valproate once daily for 4 days and after induction with rifampin (INN, rifampicin) pretreatment (600 mg once daily for 10 days), with a washout period of 10 days between. The plasma concentrations of lorazepam and lorazepam glucuronide were analyzed before and at 0.25, 0.5, 1, 1.5, 2, 4, 6, 8, 12, 24, and 48 hours after lorazepam administration by liquid chromatography‐tandem mass spectrometry. Visual analog scale assessments and psychomotor coordination tests were administered before and up to 12 hours after drug administration. Results The UGT2B15*2/*2 group showed 0.58‐fold (95% confidence interval, 0.43–0.72; P <.0001) lower systemic clearance during the basal state and 1.37‐fold (95% confidence interval, 1.05–1.88; P = .037) higher area under the visual analog scale‐time curve during the induced state compared with the UGT2B15*1/*1 group. The mean systemic clearance of lorazepam decreased by 20% in the inhibited state and increased by 140% in the induced state. During the inhibited or induced state, absolute values of clearance were consistently lower in the *2/*2 group, but the percent changes from baseline did not differ significantly by genotype. Conclusions Our results suggest that the UGT2B15*2 polymorphism is a major determinant of interindividual variability with respect to the pharmacokinetics and pharmacodynamics of lorazepam. Clinical Pharmacology & Therapeutics (2005) 77 , 486–494; doi: 10.1016/j.clpt.2005.02.006