Effect of Isavuconazonium Sulfate and Posaconazole Delayed Release Tablets on Tacrolimus Dose-to-Concentration Ratios

Limited evidence exists on the effect of isavuconazonium sulfate and posaconazole delayed release tablets on tacrolimus dose-to-concentration ratios in lung transplant recipients. The purpose of this evaluation was to assess the impact of novel triazoles on tacrolimus dose-to-concentration ratios. This retrospective review included lung transplant recipient ≥18 years of age from January 1, 2017 to October 1, 2020 who received either posaconazole delayed release tablets or isavuconazonium sulfate for. A paired analysis evaluated outcomes pre-triazole and post-triazole initiation. Forty-one patients met evaluation criteria for inclusion. A total of 34 of 41 patients received posaconazole delayed release tablets. Of these patients, 22 of 34 were transitioned from previous triazole to posaconazole delayed release tablets and experienced a 47% reduction in tacrolimus dose-to-concentration ratio. Twelve patients were newly initiated on posaconazole delayed release tablets and experienced a 50% reduction in tacrolimus dose-to-concentration ratios. Although not statistically significant, a 30% reduction in tacrolimus dose-to-concentration ratio was observed when transitioning to isavuconazonium sulfate from previous triazole therapy. Limited data exists to provide guidance on tacrolimus dose adjustments with initiation and conversion of novel triazoles, however, this evaluation provides more knowledge on the drug interaction with novel triazoles and tacrolimus.