A large number of patients with chronic hepatitis C have not been cured with interferon-based therapy. Therefore, we evaluated the efficacy of amantadine combined with the standard of care(pegylated interferon plus ribavirin) in patients who had not responded to or had relapsed after ≥ 24 weeks of treatment with conventional interferon plus ribavirin.
Patients stratified by previous response (i.e., non-response or relapse) were randomized to 48 weeks of open-label treatment with peginterferon alfa-2a (40KD) 180 µg/week plus ribavirin 1,000/1,200 mg/day plus amantadine 200 mg/day (triple therapy), or the standard of care (peginterferon alfa-2a [40KD] plus ribavirin).
The primary outcome was sustained virological response (SVR), defined as undetectable hepatitis C virus RNA in serum (< 50 IU/mL) at end of follow-up (week 72). Among patients with a previous non-response, 12/53 (22.6%; 95% confidence interval [CI] 12.3-36.2%) randomized to triple therapy achieved an SVR compared with 16/52 (30.8%; 95% CI 18.7-45.1%) randomized to the standard of care. Among patients with a previous relapse 22/39 (56.4%; 95% CI 39.6-72.2%) randomized to triple therapy achieved an SVR compared with 23/38 (60.5%; 95% CI 43.4-76.0%) randomized to the standard of care. Undetectable HCV RNA (< 50 IU/mL) at week 12 had a high positive predictive value for SVR. A substantial proportion of non-responders and relapsers to conventional interferon plus ribavirin achieve an SVR when re-treated with peginterferon alfa-2a (40KD) plus ribavirin.
Amantadine does not enhance SVR rates in previously treated patients with chronic hepatitis C and cannot be recommended in this setting.