Probenecid interacts with the pharmacokinetics of morphine-6-glucuronide in humans.

Background: Evidence obtained from porcine cell cultures and experiments in laboratory animals indicates that transmembrane transporters may play a role in the distribution of the active morphine metabolite morphine-6-glucuronide (M6G). This was evaluated in a study in healthy volunteers.

Methods: Ten subjects received an intravenous M6G infusion for 30 min at a dosage of 0.

Effects of ABCB1 (multidrug resistance transporter) gene mutations on disposition and central nervous effects of loperamide in healthy volunteers.

Objective: Mutations in the ABCB1 gene have been associated with decreased expression and net function of P-glycoprotein (P-gp). We investigated the modulation of the central nervous effects of loperamide resulting from ABCB1 genetic variants.

Methods: On two occasions, 20 healthy volunteers received 24 mg loperamide suspension orally and, in a double-blind randomized two-way crossover fashion, 800 mg quinidine or placebo orally 1 h before loperamide.

Respiratory and miotic effects of morphine in healthy volunteers when P-glycoprotein is blocked by quinidine.

Aim: Our objective was to evaluate whether P-glycoprotein inhibition after quinidine pretreatment results in modified central nervous effects of morphine.

Methods: Twelve healthy volunteers received 7.5 mg morphine as an intravenous infusion over a 3-hour period.