Drug Interaction Report

GENERALLY AVOID: The consumption of alcohol during therapy with leflunomide may potentiate the risk of liver injury. Leflunomide has been associated with hepatotoxicity, including elevated liver transaminases, hepatitis, jaundice/cholestasis, hepatic failure, and acute hepatic necrosis,

MANAGEMENT: Patients should be advised to avoid excessive alcohol use during leflunomide treatment.

Coadministration with grapefruit juice may increase the bioavailability of oral estrogens. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall induced by certain compounds present in grapefruits. In a small, randomized, crossover study, the administration of ethinyl estradiol with grapefruit juice (compared to herbal tea) increased peak plasma drug concentration (Cmax) by 37% and area under the concentration-time curve (AUC) by 28%. Based on these findings, grapefruit juice is unlikely to affect the overall safety profile of ethinyl estradiol. However, as with other drug interactions involving grapefruit juice, the pharmacokinetic alterations are subject to a high degree of interpatient variability. Also, the effect on other estrogens has not been studied.