Strategies to Mitigate the Drug-Drug Interaction between Nirmatrelvir/Ritonavir and Tacrolimus in Allogeneic Hematopoietic Stem Cell Transplant Recipients on Azole Antifungals: Results of a Case Series.

INTRODUCTION: Nirmatrelvir/ritonavir (NIM/r) inhibits tacrolimus metabolism resulting in a profound drug-drug interaction that is further complicated by the use of azole antifungals. CASE PRESENTATIONS: We describe three strategies, in 4 patient cases, for the initiation of NIM/r in allogeneic hematopoietic stem cell transplant (alloHSCT) recipients on tacrolimus at the time of diagnosis. Patients 1 and 2 (strategy 1) experienced prolonged, elevated tacrolimus concentrations after an empiric 33% reduction in tacrolimus dose and adjustment of azole antifungal at NIM/r initiation (strategy 1) and with complete discontinuation of tacrolimus and azole antifungal at NIM/r initiation (strategy 2). Patients 3 and 4 (strategy 3) did not experience elevated tacrolimus concentrations on NIM/r treatment with complete discontinuation of tacrolimus and azole antifungal and a 12-24-h delay in NIM/r initiation. Reinitiation of tacrolimus after NIM/r completion resulted in variable tacrolimus concentrations. CONCLUSION: NIM/r-tacrolimus is a serious drug-drug interaction which can be mitigated by early discontinuation of tacrolimus and azole antifungals, close monitoring, and reinitiation of tacrolimus and antifungal 48-72 h after completion of therapy.

Quality and Clinical Outcomes Associated with a Gentamicin Use System Change for Managing Chorioamnionitis.

Chorioamnionitis is an intra-amniotic infection with serious maternal and neonatal complications. Clinical studies suggest antibiotic administration before delivery reduces the risk of complications compared to after delivery. Our center implemented a standardized intrapartum gentamicin computerized provider order entry and dosage form dispensing system intended to improve treatment initiation efficiency in hospitalized obstetric patients. The primary objective of this retrospective study was to determine if these system changes were associated with decreased time from gentamicin ordering to administration in patients with chorioamnionitis. A secondary objective was to compare clinical outcomes before and after system changes. Classification and regression tree (CART) analyses was applied to identify key predictors. Results demonstrated a trend towards reduced time to administration in the post-implementation group. Clinical outcomes were not altered. CART analysis revealed that post-implementation assignment and length of membrane rupture predicted shorter time to gentamicin initiation. This study suggests that the specific system changes we implemented were safe and improved efficiency, but additional changes are needed to have a clinically significant impact.