rifampin and apixaban

Apixaban is a substrate of cytochrome P450 3A4 (CYP3A4) and P-glycoprotein. The effects of rifampin, a strong inducer of CYP3A4 and P-glycoprotein, on the pharmacokinetics of oral and intravenous apixaban were evaluated in an open-label, randomized, sequential crossover study.. Twenty healthy participants received single doses of apixaban 5 mg intravenously on day 1 and 10 mg orally on day 3, followed by rifampin 600 mg once daily on days 5-15. Finally, participants received single doses of apixaban 5 mg intravenously and 10 mg orally separately on days 12 and 14 in one of two randomized sequences.. Apixaban, given intravenously and orally, was safe and well tolerated when administered in the presence and absence of rifampin. Apixaban absolute oral bioavailability was 49 % when administered alone and 39 % following induction by rifampin. Rifampin reduced apixaban area under the plasma concentration-time curve from time zero to infinity (AUC∞) by 39 % after intravenous administration and by 54 % after oral administration. Rifampin induction increased mean clearance by 1.6-fold for intravenous apixaban and mean apparent clearance by 2.1-fold for oral apixaban, indicating rifampin affected both pre-systemic and systemic apixaban elimination pathways.. Co-administration of apixaban with rifampin reduced apixaban exposure via both decreased bioavailability and increased systemic clearance.

Topics: Administration, Intravenous; Administration, Oral; Adult; Area Under Curve; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cross-Over Studies; Cytochrome P-450 CYP3A; Drug Interactions; Factor Xa Inhibitors; Female; Humans; Male; Pyrazoles; Pyridones; Rifampin; Young Adult

Direct oral anticoagulants, such as apixaban and rivaroxaban, are important for the treatment and prophylaxis of venous thromboembolism and to reduce the risk of stroke and systemic embolism in patients with nonvalvular atrial fibrillation. Because apixaban and rivaroxaban are predominantly eliminated by cytochrome P450 (CYP) 3A and P-glycoprotein (P-gp), concomitant use of combined P-gp and strong CYP3A4 inhibitors and inducers should be avoided. Physiologically-based pharmacokinetic models for apixaban and rivaroxaban were developed to estimate the net effect of CYP3A induction, P-gp inhibition, and P-gp induction by rifampicin. The disposition of rivaroxaban is more complex compared with apixaban because both hepatic and renal P-gp is considered to contribute to rivaroxaban elimination. Furthermore, organic anion transporter-3, a renal uptake transporter, may also contribute the elimination of rivaroxaban from systemic circulation. The models were verified with observed clinical drug-drug interactions with CYP3A and P-gp inhibitors. With the developed models, the predicted area under the concentration time curve and maximum concentration ratios were 0.43 and 0.48, respectively, for apixaban, and 0.50-0.52 and 0.72-0.73, respectively, for rivaroxaban when coadministered with 600 mg multiple doses of rifampicin and that were very close to observed data. The impact of each of the elimination pathways was assessed for rivaroxaban, and inhibition of CYP3A led to a larger impact over intestinal and hepatic P-gp. Inhibition of renal organic anion transporter-3 or P-gp led to an overall modest interaction. The developed apixaban and rivaroxaban models can be further applied to the investigation of interactions with other P-gp and/or CYP3A4 inhibitors and inducers.

Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Atrial Fibrillation; Biological Transport; Cytochrome P-450 CYP3A; Cytochrome P-450 CYP3A Inducers; Cytochrome P-450 CYP3A Inhibitors; Drug Interactions; Embolism; Factor Xa Inhibitors; Humans; Pyrazoles; Pyridones; Rifampin; Rivaroxaban; Stroke; Venous Thromboembolism