Drug Interaction Report

GENERALLY AVOID: Theoretically, hemin may potentiate the risk of bleeding in patients treated with agents that affect hemostasis such as anticoagulants, platelet inhibitors, thrombin inhibitors, thrombolytic agents, or agents that commonly cause thrombocytopenia. Hemin has exhibited mild, transient anticoagulant effects during clinical studies. Thrombocytopenia and coagulopathy including prolonged prothrombin time and prolonged partial thromboplastin time have been reported during postmarketing use. The extent and duration of the hypocoagulable state induced by hemin are not known.

MANAGEMENT: The use of hemin with concurrent anticoagulant therapy should be avoided. Caution is advised if hemin is used in combination with other drugs that affect hemostasis such as platelet inhibitors, thrombin inhibitors, thrombolytic agents, or agents that commonly cause thrombocytopenia. Close clinical and laboratory observation for hematologic complications is recommended. Patients should be advised to promptly report any signs of bleeding to their physician, including pain, swelling, headache, dizziness, weakness, prolonged bleeding from cuts, increased menstrual flow, vaginal bleeding, nosebleeds, bleeding of gums from brushing, unusual bleeding or bruising, red or brown urine, or red or black stools.

ADJUST DOSING INTERVAL: Food may alter the oral bioavailability of cabozantinib. When healthy subjects were given a single 140 mg oral dose with a high-fat meal, cabozantinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 41% and 57%, respectively, relative to administration under fasting conditions. In clinical studies, patients were administered cabozantinib without food.

GENERALLY AVOID: Coadministration with grapefruit juice is likely to increase the plasma concentrations of cabozantinib, which is primarily metabolized by CYP450 3A4. However, the interaction has not been studied. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit.

MANAGEMENT: Cabozantinib should be administered at least one hour before or two hours after a meal. The consumption of grapefruit, grapefruit juice, and supplements that contain grapefruit extract should be avoided.