Effect of the UGT2B15 genotype on the pharmacokinetics, pharmacodynamics, and drug interactions of intravenous lorazepam in healthy volunteers.
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.
Chung
Jae-Yong
JY
Department of Pharmacology and Clinical Pharmacology Unit, Seoul National University College of Medicine and Hospital, Seoul, Korea.
Cho
Joo-Youn
JY
Yu
Kyung-Sang
KS
Kim
Jung-Ryul
JR
Jung
Hye-Ryung
HR
Lim
Kyoung-Soo
KS
Jang
In-Jin
IJ
Shin
Sang-Goo
SG
D000328:Adult; D004347:Drug Interactions / Q000235:genetics; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics / Q000494:pharmacology; D005260:Female; D005838:Genotype; D014453:Glucuronosyltransferase / Q000235:genetics*; D006801:Humans; D006993:Hypnotics and Sedatives / Q000493:pharmacokinetics* / Q000494:pharmacology; D007262:Infusions, Intravenous; D008140:Lorazepam / Q000493:pharmacokinetics* / Q000494:pharmacology; D008297:Male; D011110:Polymorphism, Genetic; D012293:Rifampin / Q000493:pharmacokinetics / Q000494:pharmacology; D014635:Valproic Acid / Q000493:pharmacokinetics / Q000494:pharmacology
D004791:Enzyme Inhibitors; D006993:Hypnotics and Sedatives; D014635:Valproic Acid; D014453:Glucuronosyltransferase; C472000:UDP-glucuronosyltransferase 2B15, human; D008140:Lorazepam; D012293:Rifampin