amiodarone and apixaban

Amiodarone inhibits hepatic CYP3A4 and P-glycoprotein (P-gp), both of which are involved in the elimination of apixaban. This reduces apixaban metabolism and transport, leading to increased systemic exposure and anticoagulant effect.

Elevated apixaban concentrations raise the risk of bleeding, including gastrointestinal, intracranial, and other serious haemorrhage. The risk is amplified in patients with renal impairment, advanced age, or low body weight. Bleeding may manifest as ecchymoses, epistaxis, melaena, or more severe events.

Concomitant use of amiodarone and apixaban may require caution. Check the current apixaban prescribing information, as some formularies advise a reduced apixaban dose (e.g., 2.5 mg twice daily) when given with strong inhibitors of both CYP3A4 and P-gp. If no dose reduction is made, closely monitor the patient for clinical evidence of bleeding. Reassess the need for amiodarone and consider alternative anti-arrhythmic options when possible.

The interaction is supported by pharmacokinetic studies showing that inhibition of CYP3A4 and P-gp can increase apixaban exposure. The magnitude of the effect is modest compared with strong inhibitors such as ketoconazole; a clinically relevant increase in bleeding risk is expected but is not universally mandated to avoid co-prescription. Clinical guidelines vary, so always refer to the current product label or local protocols.