PT  - JOURNAL ARTICLE
AU  - Armel Stockis
AU  - Shikiko Watanabe
AU  - André J. Scheen
AU  - Dominique Tytgat
AU  - Brigitte Gerin
AU  - Maria Rosa
AU  - Hugues Chanteux
AU  - Jean-Marie Nicolas
TI  - Effect of Rifampin on the Disposition of Brivaracetam in Human Subjects: Further Insights into Brivaracetam Hydrolysis
AID  - 10.1124/dmd.115.069161
DP  - 2016 Jun 01
TA  - Drug Metabolism and Disposition
PG  - 792--799
VI  - 44
IP  - 6
4099  - http://dmd.aspetjournals.org/content/44/6/792.short
4100  - http://dmd.aspetjournals.org/content/44/6/792.full
SO  - Drug Metab Dispos2016 Jun 01; 44
AB  - Brivaracetam (BRV) is a high-affinity synaptic vesicle protein 2A ligand developed for the treatment of uncontrolled partial-onset seizures. The present phase I, open-label, two-way crossover study was designed to assess the effect of rifampin on the pharmacokinetics of BRV and its hydroxy (BRV-OH), acid (BRV-AC), and hydroxy acid (BRV-OHAC) metabolites. Twenty-six healthy subjects received BRV (150-mg single oral dose) either alone or following 5 days of rifampin 600 mg/day. BRV and its metabolites were examined for their plasma profiles and urinary excretion. Pharmacokinetic modeling was developed to estimate the rate constants of the various metabolic routes. Parallel in vitro assays were conducted to characterize the hydrolysis of BRV to BRV-AC as well as to identify any potential effect of rifampin on the hydrolysis reaction. Rifampin did not significantly affect the maximum plasma concentration (Cmax) of BRV, but decreased its area under the curve (AUC) by 45%. In addition, rifampin significantly increased the AUC of BRV-OH (+109%), decreased the AUC of BRV-AC (−53%), but had little effect on BRV-OHAC (−10%). In vitro assays showed that the major urinary metabolite BRV-AC (33% of the dose) was likely to be formed by amidase EC 3.5.1.4. In vitro data indicated that the enzyme was not significantly inhibited nor induced by rifampin. Modeling confirmed that all of the observed changes in vivo were secondary to the induction of the CYP2C19-mediated hydroxylation of BRV to BRV-OH (3.7-fold increase in the rate constant).