Diego R Falci, Alessandro C Pasqualotto

The triazole class of antifungal drugs comprises first-line agents for the treatment of several invasive fungal diseases. Isavuconazole is a novel broad-spectrum triazole agent. Here we summarize its characteristics and compare it with the currently available antifungal agents. Isavuconazole is administered as a prodrug, and it is water soluble. Oral and intravenous formulations are available. Its intravenous formulation does not contain cyclodextrin, which is an advantage over voriconazole, considering the potential for nephrotoxicity of cyclodextrin. As with other azoles, isavuconazole requires a loading dose. Due to its prolonged half-life, a once-a-day regimen is possible. Considering that isavuconazole shares the same mechanism of action with the other triazoles, cross-resistance is an important concern in the class. Tolerability and safety profiles are favorable, and no serious adverse events have been consistently reported. Significant interactions with drugs metabolized by cytochrome P450 are expected to occur, especially with substrates and inducers of the CYP3A4 enzyme. Isavuconazole has in vitro activity against most medically important fungi, including species of Candida, Aspergillus, and Cryptococcus. It has some activity against the agents of mucormycosis. Clinical data regarding isavuconazole remain limited because ongoing trials have not yet been completed or published. Isavuconazole has the potential to become first-line therapy for invasive aspergillosis. It also has the potential for use in the context of antifungal prophylaxis, salvage therapy, or in combination regimens. Results of clinical trials are ultimately expected in order to adequately position isavuconazole in the current antifungal armamentarium.