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Estimation of the area under the concentration-time curve of racemic lansoprazole by using limited plasma concentration of lansoprazole enantiomers.

Author(s): Niioka T, Miura M, Uno T, Yasui-Furukori N, Hayakari M, Tateishi T, Suzuki T

Affiliation(s): Department of Pharmacy, Hirosaki University Hospital, Aomori, Japan.

Publication date & source: 2008-05, Eur J Clin Pharmacol., 64(5):503-9. Epub 2008 Jan 26.

OBJECTIVE: The purpose of this study was to identify the common time point that gives plasma concentrations of lansoprazole enantiomers that adequately reflect the AUC of racemic lansoprazole. METHODS: A randomized, double-blind, placebo-controlled, crossover study in three phases was conducted at intervals of 2 weeks. Eighteen healthy Japanese volunteers, including three CYP2C19 genotype groups, took a single 60-mg oral dose of lansoprazole after 6 days of pretreatment, with either clarithromycin (800 mg/day), fluvoxamine (50 mg/day), or a placebo. Multiple linear regression analysis was used to identify the most informative sampling times of (R)- and (S)-lansoprazole, using one to three samples to estimate the AUC(0-infinity) of racemic lansoprazole. RESULTS: The best R (2) in each prediction formula for the AUC of racemic lansoprazole using one, two, and three sampling points of (R)- and (S)-lansoprazole based on the data sets from all three pretreatment groups (n = 54) were 0.897, 0.930, and 0.929, respectively. The best prediction formula for the AUC of racemic lansoprazole, using the fewest sampling points of (R)- and (S)-lansoprazole, was [Formula: see text] (P < 0.001), where C(3h) is the plasma concentration 3 h after administration, G1 = 1 for the homozygous extensive metabolizer (EM) and 0 for the other genotypes, G2 = 1 for the heterozygous EM and 0 for the other genotypes. CONCLUSIONS: C(3h) monitoring of (R)- and (S)-lansoprazole is a useful time point to estimate the AUC of racemic lansoprazole. This method of plasma concentration monitoring at a few time points within 3 h might be more suitable for AUC estimation than CYP2C19 genotyping, particularly when lansoprazole is co-administered with CYP inhibitors.

Page last updated: 2008-03-26

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