sisunatovir + rifampicin

Sisunatovir + rifampicin is a combination of two drugs: **sisunatovir**, a selective small molecule RSV fusion (F) protein inhibitor, and **rifampicin**, a broad-spectrum rifamycin-class antibiotic. Sisunatovir inhibits entry and fusion of respiratory syncytial virus (RSV) into host cells by targeting the RSV-F protein, thereby preventing viral replication and reducing viral load[5][6][8]. Rifampicin acts as both an antibiotic and a potent inducer of hepatic metabolic enzymes, notably cytochrome P450, and is primarily used against mycobacterial infections such as tuberculosis[7][9]. This combination is not recognized as a marketed or clinically trialed fixed-dose therapy. There are no known indications or structured clinical data supporting the use of sisunatovir and rifampicin together, and rifampicin is known to cause profound drug-drug interactions via CYP3A4 induction, which may substantially reduce the plasma levels and therapeutic effect of drugs metabolized by this pathway, including many antivirals.