Experience of a Single-Center Voriconazole TDM Bioassay for Hospitalized Patients with Invasive Fungal Infections

Information on the plasma ranges of prescribed voriconazole prophylactic and therapeutic drug levels among the patients with invasive fungal infections (IFIs) is sparsely documented from central India.

This prospective observational database study was conducted over a period of 18 months at the ICMR Mycology Advanced Resource Center of a tertiary care hospital in central India. It included 25 voriconazole samples from 18 patients undergoing routine therapeutic drug monitoring (TDM). Clinico-mycological characteristics, target concentration ranges for prophylactic and therapeutic prescriptions, and clinical outcomes were evaluated among enrolled patients.

Out of the 25 samples, 8 (32%) were random and 17 (68%) were trough samples. 33.3% (6/18) had repeat samples sent for analysis. Out of the 18 patients enrolled, 10 (55%) received prophylactic, while 8 (44%) were received therapeutic doses of voriconazole. Overall mean concentration of voriconazole in trough samples was 3.93 μg/ml, and in random samples was 2.38 μg/ml. Both these values were within the normal range. Commonest drug-drug interaction (DDI), between proton pump inhibitor (PPI) use and voriconazole was evident in supratherapeutic voriconazole concentrations. With small sample size, exploratory nature of this study and without a multivariable analysis; the association of PPIs alone for supratherapeutic voriconazole concentrations cannot be established.

The research highlighted notable pharmacokinetic variances between children and adults who received voriconazole, particularly concerning the rate of absorption, bioavailability, and metabolism. This study emphasizes the need for antifungal TDM in developing nations with resource limited settings in better understanding of IFI management.