Drug Interaction Report

MONITOR: Immunosuppressed patients may have diminished response to diagnostic skin test antigens due to suppression of cell-mediated, delayed-type hypersensitivity. Falsely insignificant or false-negative results may occur in such patients, which may include those who have recently received or are receiving immunosuppressive agents, antilymphocyte globulins, alkylating agents, antimetabolites, radiation, some antirheumatic agents, high dosages of corticosteroids or adrenocorticotropic agents (e.g., greater than or equal to 2 mg/kg/day or 20 mg/day of prednisone or equivalent for 14 consecutive days or more), or long-term topical or inhaled corticosteroids.

MANAGEMENT: Clinicians should be aware of the potential for falsely insignificant or false-negative results when administering diagnostic skin test antigens to patients treated with immunosuppressive agents.

ADJUST DOSING INTERVAL: Food enhances the oral bioavailability of bosutinib. When given with a high-fat meal, bosutinib peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 1.8- and 1.7-fold, respectively.

GENERALLY AVOID: Coadministration with grapefruit juice is likely to increase the plasma concentrations of bosutinib, 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: Bosutinib should be administered with a meal. The consumption of grapefruit, grapefruit juice, and supplements that contain grapefruit extract should be avoided.