Itraconazole: Precautions regarding drug interactions and bioavailability

Abstract

Objective: To describe patients with fungal infections in whom drug interactions and bioavailability problems were associated with itraconazole treatment failure. Design: Retrospective chart review. Setting: Two tertiary care university-affiliated teaching hospitals. Population Studied: Itraconazole-treated patients between 1990 and 1992. Main Results: Four patients treated with itraconazole were identified in whom suboptimal serum itraconazole levels were associated with relapse of disseminated histoplasmosis, treatment failure of invasive aspergillosis or development of superficial mycoses. Low serum itraconazole levels were associated with concurrent therapy with rifampin or agents inhibiting gastric acid secretion, with administration of itraconazole capsule contents through a nasogastric tube or with the presence of AIDS. Conclusions: It is recommended that serum itraconazole levels be measured in patients with potentially life-threatening mycoses if coexistent factors may interfere with itraconazole therapy.