5 Things to Know About Antifungal Therapeutic Drug Monitoring

Antifungal therapeutic drug monitoring is a critical component of individualized, precision treatment for fungal infections and for antifungal stewardship.^[1,2] Antifungal therapeutic drug monitoring is a method to optimize the antifungal treatment regimen for an individual patient by measuring antifungal drug concentrations in a patient's biologic fluids and applying well-described pharmacokinetic principles to adjust the treatment regimen.^[3] Measurement of antifungal concentrations is usually performed by analytical assays, such as high-performance liquid chromatography or liquid chromatography-mass spectrometry; bioassays are available for certain azole antifungals (eg, itraconazole). Infectious Diseases Society of America's Guidelines for treatment of fungal diseases like candidiasis, aspergillosis, histoplasmosis, coccidioidomycosis, and blastomycosis recommend therapeutic drug monitoring for certain antifungals, particularly for triazole antifungals (eg, itraconazole, voriconazole, posaconazole)^[4,5,6,7,8] Antifungal therapeutic drug monitoring can help improve outcomes through minimizing toxicity associated with supratherapeutic drug levels and prevent treatment failure from subtherapeutic levels.^[9,10,11,12] Also, in vitro studies have shown that suboptimal drug levels can lead to antifungal resistance, supporting therapeutic drug monitoring's potential role in preventing the emergence of antifungal-resistant organisms.^[13]

Recent studies suggest that antifungal therapeutic drug monitoring is underutilized, leading to missed opportunities to address sub- and supratherapeutic drug levels and improve patient outcomes. An analysis of a hospital discharge data set showed that only 16% of therapeutic drug monitoring–eligible patients receiving itraconazole, posaconazole, or voriconazole had drug level monitoring performed.