Drug Interaction Report

GENERALLY AVOID: Coadministration with potent inducers of CYP450 3A4 that also induce P-glycoprotein (P-gp) may significantly decrease the plasma concentrations of apixaban, which is a substrate of both the isoenzyme and the efflux transporter. When apixaban was coadministered with 600 mg/day of rifampin, a dual P-gp and potent CYP450 3A4 inducer, mean apixaban peak plasma concentration (Cmax) and systemic exposure (AUC) decreased by 42% and 54%, respectively. Reduced efficacy, increased stroke rates, and paradoxically, an increased risk of bleeding have been reported in a clinical study in patients with atrial fibrillation taking apixaban with concomitant dual P-gp and potent CYP450 3A4 inducers compared with apixaban alone.

MANAGEMENT: Concomitant use of apixaban with dual P-gp and potent CYP450 3A4 inducers should generally be avoided, since efficacy of apixaban may be compromised.

GENERALLY AVOID: Concurrent use of rifampin in patients who ingest alcohol daily may result in an increased incidence of hepatotoxicity. The increase in hepatotoxicity may be due to an additive risk as both alcohol and rifampin are individually associated with this adverse reaction. However, the exact mechanism has not been established.

ADJUST DOSING INTERVAL: Administration with food may reduce oral rifampin absorption, increasing the risk of therapeutic failure or resistance. In a randomized, four-period crossover phase I study of 14 healthy male and female volunteers, the pharmacokinetics of single dose rifampin 600 mg were evaluated under fasting conditions and with a high-fat meal. Researchers observed that administration of rifampin with a high-fat meal reduced rifampin peak plasma concentration (Cmax) by 36%, nearly doubled the time to reach peak plasma concentration (Tmax) but reduced overall exposure (AUC) by only 6%.

MANAGEMENT: The manufacturer of oral forms of rifampin recommends administration on an empty stomach, 30 minutes before or 2 hours after meals. Patients should be encouraged to avoid alcohol or strictly limit their intake. Patients who use alcohol and rifampin concurrently or have a history of alcohol use disorder may require additional monitoring of their liver function during treatment with rifampin.