Effect of a 150mg dose of rifabutin on serum itraconazole levels in patients with coexisting chronic pulmonary aspergillosis and Mycobacterium avium complex lung disease.

Abstract

Patients with coexisting chronic pulmonary aspergillosis and nontuberculous mycobacterial lung disease may undergo treatment with both the antifungal itraconazole and the antimycobacterial rifamycin. However, rifamycins interact with itraconazole. We examined the effects of a 150mg dose of rifabutin on serum itraconazole levels and found significantly lower levels in 28 patients receiving itraconazole with rifabutin (median, 0.65μg/ml) compared with 65 patients receiving itraconazole alone (median 3.45μg/ml, P<0.001). One-third of patients receiving itraconazole and rifabutin reached the therapeutic range of serum itraconazole concentration. Therapeutic drug monitoring is strongly recommended during concomitant use of rifabutin and itraconazole.