Drug Interaction Report

Theoretically, coadministration of dapsone with inducers of CYP450 3A4 such as rifamycins, anticonvulsants, barbiturates, and St. John's wort may increase the formation of dapsone hydroxylamine, a metabolite associated with hemolysis. Dose-related hemolysis is the most common adverse event associated with oral dapsone in both patients with or without glucose-6-phosphate dehydrogenase (G6PD) deficiency. While clinical studies have not demonstrated evidence of clinically significant anemia in patients treated with dapsone 5% gel for acne vulgaris, an increased reticulocyte count and a decreased hemoglobin level were noted to be associated in a G6PD-deficient patient. Exposure to dapsone from the recommended topical dose is about 1% of that from a 100 mg oral dose.

ADJUST DOSING INTERVAL: Food may reduce as well as delay the absorption of dabrafenib. In study subjects, administration of dabrafenib with a high-fat meal decreased peak plasma concentration (Cmax) and systemic exposure (AUC) by 51% and 31%, respectively, and delayed median Tmax by approximately 3.6 hours compared to administration in the fasted state.

MANAGEMENT: Dabrafenib should be taken at least 1 hour before or 2 hours after a meal.