A simple and sensitive HPLC-FL method for bioanalysis of velpatasvir, a novel hepatitis C virus NS5A inhibitor, in rat plasma: Investigation of factors determining its oral bioavailability

•A new bioanalytical HPLC-FL method to determine velpatasvir (VEL).•The method offered sufficient sensitivity, comparable to LC-MS/MS methods.•VEL exhibited moderate intestinal permeability and significant biliary excretion.•VEL was significantly metabolized in the liver, but not in the intestine.•Gut absorption and hepatic first-pass metabolism mainly determined the oral bioavailability of VEL.