Letermovir and tacrolimus interaction effects in hematopoietic cell transplantation recipients receiving moderate cytochrome P450 3A4 inhibitors for antifungal prophylaxis.

These results demonstrate a reduction in tacrolimus dosing requirements for patients receiving tacrolimus and letermovir with concomitant moderate CYP3A4 inhibitors. The results of this interaction suggest that frequent monitoring of tacrolimus trough levels is warranted when starting letermovir and that empiric reduction of tacrolimus dosing upon letermovir initiation should be considered.