Drug Interactions between colchicine and Ibrance

GENERALLY AVOID: Coadministration with grapefruit juice may increase the serum concentrations of colchicine. Clinical toxicity including myopathy, neuropathy, multiorgan failure, and pancytopenia may occur. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism and P-glycoprotein efflux in the gut wall by certain compounds present in grapefruits. A published case report describes an eight-year-old patient with familial Mediterranean fever who developed acute clinical colchicine intoxication after ingesting approximately one liter of grapefruit juice per day for two months prior to hospital admission while being treated with colchicine 2 mg/day. Her condition progressed to circulatory shock and multiorgan failure, but she recovered with supportive therapy after 24 days in the hospital. In a study of 21 healthy volunteers, administration of 240 mL grapefruit juice twice a day for 4 days was found to have no significant effect on the pharmacokinetics of a single 0.6 mg dose of colchicine. However, significant interactions have been reported with other CYP450 3A4 inhibitors such as clarithromycin, diltiazem, erythromycin, ketoconazole, ritonavir, and verapamil.

MANAGEMENT: Patients treated with colchicine should be advised to avoid the consumption of grapefruit and grapefruit juice, and to contact their physician if they experience symptoms of colchicine toxicity such as abdominal pain, nausea, vomiting, diarrhea, fatigue, myalgia, asthenia, hyporeflexia, paresthesia, and numbness.

GENERALLY AVOID: Grapefruit and/or grapefruit juice may increase the systemic exposure to palbociclib. 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 palbociclib may increase the risk of adverse effects such as infections, neutropenia, leukopenia, anemia, thrombocytopenia, anorexia, nausea, vomiting, diarrhea, stomatitis, alopecia, asthenia, peripheral neuropathy, and epistaxis.

ADJUST DOSING INTERVAL: Food may enhance the oral bioavailability of palbociclib capsules and reduce the intersubject variability of palbociclib exposure. According to the product labeling, absorption and exposure of palbociclib from its oral capsule formulation were very low in approximately 13% of the population when taken in the fasted state. Food intake increased the palbociclib exposure in this small subset of the population but did not alter exposure in the rest of the population to a clinically relevant extent. Compared to palbociclib capsules given under overnight fasted conditions, the population average palbociclib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 38% and 21%, respectively, when given with high-fat, high-calorie food (approximately 800 to 1000 calories; 150, 250, and 500 to 600 calories from protein, carbohydrate and fat, respectively); by 27% and 12%, respectively, when given with low-fat, low-calorie food (approximately 400 to 500 calories; 120, 250, and 28 to 35 calories from protein, carbohydrate and fat, respectively); and by 24% and 13%, respectively, when given with moderate-fat, standard calorie food (approximately 500 to 700 calories; 75 to 105, 250 to 350 and 175 to 245 calories from protein, carbohydrate and fat, respectively) one hour before and two hours after palbociclib capsule dosing.

MANAGEMENT: Patients should avoid consumption of grapefruit or grapefruit juice while on treatment with palbociclib. To avoid variability in drug absorption between doses, palbociclib capsules should be taken with food. Palbociclib tablet formulations may be taken with or without food.