The pregnane X receptor agonist St John's Wort has no effects on the pharmacokinetics and pharmacodynamics of repaglinide

Abstract

Background and objectives: St John's wort (SJW; Hypericum perforatum) has been one of the most commonly used herbal remedies for mood disorders. This study aimed to investigate the effect of SJW, a pregnane X receptor (PXR) agonist, on the pharmacokinetics and pharmacodynamics of repaglinide, a widely consumed glucose-lowering drug.

Methods: In a two-phase, randomized, crossover study with a 4-week washout period between phases, 15 healthy subjects with specific solute carrier organic anion transporter family member 1B1 (SLCO1B1) genotypes were given pretreatment with SJW 325 mg or placebo three times daily for 14 days, and a single dose of repaglinide 1 mg was administered followed by 75 g glucose at 15 minutes after repaglinide administration.

Results: In all subjects, SJW had no effect on the total area under the plasma concentration-time curve from time zero to infinity (AUC(∞)), the peak plasma concentration (C(max)) or the elimination half-life (t(½)) of repaglinide. In addition, SJW had no significant effect on the blood glucose-lowering and insulin-elevating effects of repaglinide.

Conclusion: Consumption of SJW for 14 days had no clinically significant effect on the pharmacokinetics and pharmacodynamics of repaglinide.