Maribavir does not significantly influence tacrolimus dose requirements in solid organ transplant recipients

To the Editor: Cytomegalovirus (CMV) infection remains a common opportunistic infection in solid organ transplant (SOT) recipients that is associated with significant morbidity.1 Maribavir, a novel antiviral agent, gained FDA approval in December 2021 for the treatment of CMV that is refractory to other available antiviral agents. According to the product labeling, maribavir is a weak inhibitor of cytochrome P450 (CYP) 3A4 and an inhibitor of P-glycoprotein.2 Though previous pharmacokinetic studies have not identified any alterations in CYP 3A4 activity caused by maribavir, it is uncertain if this is consistent in the presence of other CYP3A4 substrates in a real-world setting.3 Our study aims to assess if any clinically significant drug–drug interactions exist between maribavir and tacrolimus in SOT recipients.