Rifampicin is a potent and broad spectrum antibiotic against bacterial pathogens. Rifampicin has anti-influenza virus activities. In Vitro: Rifampicin (100 mg/mL) can block the functional activity of P-glycoprotein. Rifampicin is not a substract for P-glycoprotein. The mechanism of rifampicin resistance is unassociated with the functional activity of P-glycoprotein^[3]. In Vivo: Rifampicin (200, 400 mg/kg) can induce fatty liver at high concentration^[1]. Rifampicin (30 mg/kg, i.p.) treatment of S464P biofilms in vivo results in a slight decline, but earlier rebinds in bioluminescence from these catheters compared with the parental signal, whereas rifampicin has no affect on bioluminescence in mice infected with mutant H481Y^[2].