In Vitro and Clinical Evaluation of Potential Interactions of Bemnifosbuvir with Drug Transporters.

Bemnifosbuvir is a novel oral guanosine nucleotide prodrug candidate for the treatment of chronic hepatitis C virus infection. Potential drug-drug interactions (DDIs) of bemnifosbuvir as a substrate or perpetrator with regard to ATP-binding cassette (ABC) and solute carrier (SLC) transporters were evaluated in vitro and in clinical studies. Bemnifosbuvir was demonstrated in vitro as a substrate and inhibitor of the ABC transporters' P-glycoprotein (P-gp), as an inhibitor of the breast cancer resistance protein (BCRP), as well as a weak inhibitor of SLC transporters, including organic anion transporting polypeptide 1B1 (OATP1B1). Phase 1 studies in healthy participants were subsequently conducted to assess the clinical significance of transporter-mediated DDI potentials of bemnifosbuvir as a precipitant using digoxin and rosuvastatin as P-gp and BCRP/OATP1B1 index substrates, respectively. A single dose of 0.25 mg digoxin or 10 mg rosuvastatin was administered alone and with 1100 mg bemnifosbuvir, either simultaneously or staggered. Simultaneous administration of a single dose of 1100 mg bemnifosbuvir increased total plasma exposure of both drugs by less than 20%, and transiently increased the peak plasma exposure of digoxin and rosuvastatin by 78% and 40%, respectively. Staggered dosing reduced the magnitude of changes in peak exposure to digoxin and rosuvastatin. No serious adverse events or drug discontinuations were observed. Dose adjustments are therefore unlikely for drugs that are substrates of P-gp or BCRP/OAT1B1 when coadministered with bemnifosbuvir, and staggered dosing may further reduce any DDI risk.