Drug Interactions between nirmatrelvir / ritonavir and zuranolone

ADJUST DOSING INTERVAL: Administration with food may modestly affect the bioavailability of ritonavir from the various available formulations. When the oral solution was given under nonfasting conditions, peak ritonavir concentrations decreased 23% and the extent of absorption decreased 7% relative to fasting conditions. Dilution of the oral solution (within one hour of dosing) with 240 mL of chocolate milk or a nutritional supplement (Advera or Ensure) did not significantly affect the extent and rate of ritonavir absorption. When a single 100 mg dose of the tablet was administered with a high-fat meal (907 kcal; 52% fat, 15% protein, 33% carbohydrates), approximately 20% decreases in mean peak concentration (Cmax) and systemic exposure (AUC) were observed relative to administration after fasting. Similar decreases in Cmax and AUC were reported when the tablet was administered with a moderate-fat meal. In contrast, the extent of absorption of ritonavir from the soft gelatin capsule formulation was 13% higher when administered with a meal (615 KCal; 14.5% fat, 9% protein, and 76% carbohydrate) relative to fasting.

MANAGEMENT: Ritonavir should be taken with meals to enhance gastrointestinal tolerability.

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of zuranolone. When administered with a low-fat meal (e.g., 400 to 500 calories, 25% fat), zuranolone peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 3.5- and 1.8-fold, respectively, compared to administration under fasted conditions. Zuranolone was administered with food in the premarketing study population. The efficacy of zuranolone when administered in the fasted state is unknown.

GENERALLY AVOID: Concomitant use of zuranolone with central nervous system (CNS) depressants, including alcohol, may potentiate adverse effects such as somnolence, confusion, dizziness, and gait disturbance.

MANAGEMENT: Zuranolone must be administered with fat-containing food (e.g., 400 to 1,000 calories, 25% to 50% fat) according to the manufacturer. Patients should also be advised to avoid or limit consumption of alcohol and to avoid activities requiring mental alertness such as driving or operating hazardous machinery until at least 12 hours after administration of zuranolone.