Drug Interaction Report

ADJUST DOSE: Coadministration with potent inhibitors of CYP450 3A4 may increase the plasma concentrations of panobinostat, which is partially metabolized by the isoenzyme. In 14 patients with advanced or metastatic solid tumors, administration of a single 20 mg dose of panobinostat on day 4 of multiple once daily dosing of 400 mg ketoconazole, a potent CYP450 3A4 inhibitor, resulted in 1.6- and 1.8-fold increases in mean panobinostat peak plasma concentration (Cmax) and systemic exposure (AUC), respectively, compared to administration of panobinostat alone. Ketoconazole caused a greater than 2-fold increase in Cmax and AUC of panobinostat in a limited number of patients. QTc prolongation >30 ms over baseline occurred in 5 patients during concomitant administration, compared to 4 patients during panobinostat alone and 3 patients during ketoconazole alone. Other ECG abnormalities occurred in 6 patients during concomitant administration and 3 patients during either panobinostat or ketoconazole alone. No significant alteration in time to maximum concentration (Tmax) or half-life of panobinostat was observed.

MANAGEMENT: For the treatment of multiple myeloma in combination with bortezomib and dexamethasone, the dose of panobinostat should be reduced to 10 mg when coadministered with potent CYP450 3A4 inhibitors.

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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.

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ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of ombitasvir, paritaprevir, ritonavir, and dasabuvir. Relative to fasting conditions, administration of ombitasvir, paritaprevir, ritonavir, and dasabuvir with a moderate-fat meal (approximately 600 Kcal; 20% to 30% calories from fat) increased the mean systemic exposure (AUC) by 82%, 211%, 49%, and 30%, respectively. Relative to fasting conditions, administration of ombitasvir, paritaprevir, ritonavir, and dasabuvir with a high-fat meal (approximately 900 Kcal; with 60% calories from fat) increased the mean AUC by 76%, 180%, 44%, and 22%, respectively.

MANAGEMENT: Ombitasvir/paritaprevir/ritonavir plus dasabuvir should always be administered with a meal. The fat or calorie content does not matter.

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GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of panobinostat. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Increased exposure to panobinostat may increase the risk of adverse effects such as nausea, vomiting, diarrhea, anorexia, peripheral edema, cardiotoxicity, ECG abnormalities, electrolyte disturbances, bleeding complications, hepatotoxicity, and myelosuppression.

Food may delay the rate of absorption of panobinostat, but does not significantly affect the overall extent of absorption. When a single oral dose of panobinostat was administered to 36 patients with advanced cancer 30 minutes after a high-fat meal, panobinostat peak plasma concentration (Cmax) and systemic exposure (AUC) were approximately 44% and 16% lower, respectively, compared to administration under fasting conditions. The median time to maximum concentration (Tmax) was prolonged by 2.5 hours.

MANAGEMENT: Patients should avoid consumption of grapefruit or grapefruit juice during treatment with panobinostat. The manufacturer also recommends avoiding star fruit, Seville oranges, pomegranate, and pomegranate juice. Panobinostat may be administered with or without food.

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