Drug Interaction Report

Coadministration with remdesivir may increase the plasma concentrations of drugs metabolized via CYP450 3A4, but many sources indicate that clinically significant interactions are unlikely. The proposed mechanism is inhibition of CYP450 3A4 by remdesivir. Two drug interaction studies were conducted using the sensitive CYP450 3A4 substrate, midazolam. In the first study, healthy volunteers (n=19) received a single dose of remdesivir (200 mg) and a single dose of midazolam (2.5 mg), which resulted in midazolam's maximum concentration (Cmax) and systemic exposure (AUC) increasing by 29% and 20%, respectively. In the second study, healthy volunteers (n=14) received remdesivir (200 mg once, followed by 100 mg daily) for a total of 10 doses and a single dose of midazolam (2.5 mg) administered with the last dose of remdesivir. Midazolam's Cmax and AUC increased by 45% and 30%, respectively. Both studies indicated that remdesivir is a weak in vivo inhibitor of CYP450 3A4; however, some authorities consider these findings to be clinically insignificant.

ADJUST DOSING INTERVAL: Food significantly increases the oral bioavailability of sonidegib. According to the product labeling, administration of sonidegib with a high-fat meal (approximately 1000 calories; 50% from fat) increased mean sonidegib peak plasma concentration (Cmax) and systemic exposure (AUC) by 7.4- to 7.8-fold.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of sonidegib. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. Increased exposure to sonidegib may increase the risk of adverse effects such as musculoskeletal toxicity, fatigue, nausea, vomiting, diarrhea, anorexia, weight loss, alopecia, pruritus, and dysgeusia.

MANAGEMENT: Sonidegib should be administered on an empty stomach, at least 1 hour before or 2 hours after a meal. Patients should avoid consumption of grapefruit or grapefruit juice during treatment with sonidegib.