Drug Interactions between sofosbuvir / velpatasvir / voxilaprevir and talazoparib

MONITOR: Coadministration with inhibitors of organic anion transporting polypeptides (OATP) 1B1 and/or 1B3 may increase the plasma concentrations of voxilaprevir, which is a substrate of the hepatic uptake transporters. When a single 100 mg dose of voxilaprevir was administered with a single 600 mg dose of the potent OATP 1B1/1B3 inhibitor cyclosporine (n=24), mean voxilaprevir peak plasma concentration (Cmax) and systemic exposure (AUC) increased by approximately 19.0- and 9.4-fold, respectively. Inhibition of P-glycoprotein (P-gp)- and breast cancer resistance protein (BCRP)-mediated intestinal transport and CYP450 3A4-mediated metabolism of voxilaprevir may also contribute to the overall interaction with cyclosporine. The safety of such high levels of voxilaprevir has not been established.

MANAGEMENT: Caution and monitoring are advised when voxilaprevir is used with OATP 1B1 or 1B3 inhibitors.

MONITOR: Coadministration with inhibitors of P-glycoprotein (P-gp) and/or breast cancer resistance protein (BCRP) may increase the plasma concentrations of talazoparib, which has been shown in vitro to be a substrate of both efflux membrane transporters. In clinical studies, administration of talazoparib with the P-gp inhibitors amiodarone, carvedilol, clarithromycin, itraconazole, and verapamil resulted in an approximate 45% increase in talazoparib exposure and an increase in the rate of talazoparib dose reduction. In contrast, coadministration with the P-gp inhibitors azithromycin, atorvastatin, diltiazem, felodipine, fluvoxamine, and quercetin increased talazoparib exposure by just 8%. The effect of BCRP inhibitors on the pharmacokinetics of talazoparib has not been studied.

MANAGEMENT: No initial dosage adjustment is recommended by the manufacturer when talazoparib is coadministered with inhibitors of BCRP and/or P-gp other than amiodarone, carvedilol, clarithromycin, itraconazole, or verapamil. However, patients should be closely monitored for adverse effects such as myelosuppression and myelodysplastic syndrome/acute myeloid leukemia, and dosage adjustments made or treatment withheld as needed in accordance with the product labeling.