Sofosbuvir/velpatasvir (with or without ribavirin) is a complete regimen. There are no data to support coadministration with another NS5A agent such as daclatasvir.

Epclusa is a fixed dose combination of sofosbuvir and velpatasvir and should not be administered with other products containing sofosbuvir.

Coadministration of sofosbuvir (400 mg once daily) and daclatasvir (60 mg once daily) was studied in patients with chronic HCV infection. When compared to historical data, daclatasvir AUC, Cmax and Cmin decreased by 5%, 12% and 9%, respectively. There was no change in the AUC of GS-331007 (the major circulating metabolite of sofosbuvir), but Cmax decreased by 20% and Cmin increased by 40%. No dose adjustment of daclatasvir or sofosbuvir is required.

Coadministration has not been studied. Based on metabolism and clearance a clinically significant interaction is unlikely as allopurinol is metabolised by xanthine oxidase and aldehyde oxidase which are unlikely to be affected by sofosbuvir. Sofosbuvir is a prodrug and formation of its active metabolite is unlikely to be affected by comedications. [Note, the European SmPC and US Prescribing Information for allopurinol recommend reduced dose in hepatic impairment.]

Coadministration has not been studied but based on metabolism and clearance a clinically significant interaction is unlikely. Allopurinol is metabolised by xanthine oxidase which is not affected by sofosbuvir/velpatasvir. [Note, the European SmPC and US Prescribing Information for allopurinol recommend reduced dose in hepatic impairment.]

Coadministration has not been studied but based on metabolism and clearance a pharmacokinetic interaction is unlikely as allopurinol is metabolised by xanthine oxidase and aldehyde oxidase. [Note, the European SmPC and US Prescribing Information for allopurinol recommend reduced dose in hepatic impairment.]