The use of Amantadine HCl (Symmetrel, DuPont) in the treatment of chronic Hepatitis C virus infection has been recently discussed. This brief communication will provide an update on the status of the drug and its use.
An abstract was recently published (Gastroenterol 1996; 110:A1330) regarding a pilot study from Hershey Medical Center in Hersey, PA. This prospective, open-labeled study utilized Amantadine in the treatment of chronically HCV-infected patients who had previously failed treatment with alpha-interferon. Twenty-two patients were treated with Amantadine HCl at 100 mg b.i.d. for six months. The patients were used as their own controls both during and off of interferon. 20 of the 22 patients completed therapy. Complete response (defined as normalization of ALT) was observed in 6 (30%) patients at the end of treatment. Hepatitis C RNA levels were undetectable in 6 (30%) patients at completion of therapy. ALT levels are reported as significantly lower at 6 month post-therapy follow-up. No HCV RNA values are noted.
While they may initially appear encouraging, these results should be viewed with some caution. Complete response in the study was defined as normalization of ALT. It is known that many patients may normalize their ALT values but remain viremic, and relapse when taken off drug. HCV RNA is considered a better measure of treatment outcome. HCV RNA reportedly became negative in 6 (30%) patients although it is unclear if these were the same patients who had normalization of ALT. ALT levels do not correlate well with the extent of hepatic parenchymal disease, so the fact that her cohort had significantly lower ALTs 6 months post therapy is not an adequate measure of response. No information was given regarding the 6 responders and their outcome.
Chronic hepatitis C infection is a frustrating disease to attempt to treat, and current therapies are clearly inadequate. Further investigation is needed, however, with respect to Amantadine before it can be recommended as a substitute for interferon-alfa.