Antifungal Therapy: New and Evolving Therapies

Invasive fungal diseases primarily occur in immunocompromised patients. Immunosuppression has become more prevalent due to novel treatments, and this has led to a rise in the incidence of invasive fungal diseases. The antifungal armamentarium has long been insufficient and has taken quite some time to become diverse. Antifungal spectrum, tolerability, and toxicity are critical issues. Amphotericin B and its lipid formulations still have the widest spectrum, but, in spite of the better tolerance of the lipid formulations, toxicity remains a drawback, mostly with regard to renal function. Azoles constitute a heterogeneous antifungal class, in which newer molecules have an improved spectrum of activity. The main concern for the clinician when using azoles relates to the management of their many potential drug-drug interactions in an often fragile patient population. Echinocandins are better tolerated but possess a narrower antifungal spectrum and lack an oral route of administration. Still, their fungicidal activity makes them a weapon of first choice against Candida species. For certain uncommon fungal infections, antifungals such as flucytosine and terbinafine can also be useful. This article will give an overview of the mechanisms of action of currently used antifungals, as well as their spectrum of activity, clinically relevant pharmacological features, drug-drug interactions, and frequent side effects, all of which should drive the clinician's choice of agent when managing invasive fungal infections.