Update on Therapeutic Drug Monitoring of Antifungals for the Prophylaxis and Treatment of Invasive Fungal Infections

Purpose of Review: Certain antifungals used as therapy for invasive fungal disease, including the extended-spectrum triazoles, may be limited by variable pharmacokinetics and drug interactions. This is especially important when drug exposure, as measured by trough concentrations, may be linked to either efficacy or toxicity. We review the rationale, indications, and controversies in TDM of antifungals. Recent Findings: The monitoring of voriconazole drug levels is often practiced in patients that receive this triazole based on clinical data. Posaconazole delayed-release tablets achieve higher drug exposure more consistently, necessitating reconsideration of a role for therapeutic drug monitoring. Isavuconazole has predictable population kinetics, although exposure appears to be reduced in certain groups. However, the utility of isavuconazole therapeutic drug monitoring is unknown. Summary: Therapeutic drug monitoring is warranted for certain antifungals, while its utility is being reconsidered for others.