The authors state that the concomitant use of SOF/VEL and rifaximin does not impact the PK of SOF/VEL in HCV-infected patients with moderate hepatic impairment. This data suggests limited potential for P-gP or CYP induction by rifaximin, even in patients with hepatic impairment.
Sofosbuvir/velpatasvir vs rifaximin
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Study Design
This was a substudy of ASTRAL-4.Of the 268 HCV infected patients enrolled in the ASTRAL-4 study, 92 of them utilized rifaximin during the study duration. Pharmacokinetic sampling assessed the concentrations of sofosbuvir (SOF), its metabolite GS-331007, and velpatasvir (VEL). Geometric Least Square Means Ratios and 90% confidence intervals for AUC, Cmax and Ctau (if applicable) were estimated comparing HCV-infected individuals with moderate hepatic impairment concomitantly using rifaximin versus those patients not using rifaximin.
Study Results
Of patients reporting rifaximin use during the study population 81/92 (88%) used rifaximin throughtou the entire course of SOF/VEL. Chronic use of rifaximin (>14 days during treatment with SOF/VEL) was reported in 90/92 (98%) of patients. Exposures for SOF, GS-331007, and VEL were not significantly altered by the use of rifaximin. The following values were shown: for SOF, AUC was 102%, and Cmax was 98%; for GS-331007, AUC was 102 and Cmax was 103%; for VEL, AUC was 89%, Cmax was 88%, and Ctau was 91%.
References
E Mogalian, B Kirby, L Ni, S Chuang, J McNally, J Ling, et al. Evaluation of drug-drug interaction between sofosbuvir/velpatasvir and rifaximin in hcv-infected subjects with moderate hepatic impairment. abstract o_8. 17th International Workshop On Clinical Pharmacology Of Hiv And Hepatitis Therapy. Washington DC, USA. ; 2016.
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