tenofovir prodrug MK-8504

MK-8504 is an investigational small molecule antiretroviral drug developed as a novel prodrug of tenofovir, designed for the treatment of HIV-1 infection. It acts as a nucleoside reverse transcriptase inhibitor (NRTI), inhibiting the replication of HIV by blocking reverse transcriptase activity. Unlike existing daily-dosed tenofovir formulations, MK-8504 was engineered to enable less frequent dosing—potentially weekly—due to its long intracellular half-life as the active diphosphate metabolite (tenofovir diphosphate). In early clinical studies, single doses were generally well-tolerated and maintained target concentrations in peripheral blood mononuclear cells for up to 7 days. However, antiviral activity observed in monotherapy was modest and transient, raising questions about its efficacy with extended dosing intervals compared to daily regimens. The drug was developed by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc.[1][3][6][8]