MedWire News: The commonly used herbal remedy, silymarin, offers no benefit to patients with treatment-resistant hepatitis C virus (HCV) infection, a study shows.
"This was the strongest, most methodologically sound clinical trial to date of silymarin as a treatment for chronic hepatitis C infection, and we found that it had absolutely no effect on serum ALT [alanine aminotransaminase] or levels of the hepatitis C virus," said lead author, Michael Fried (University of North Carolina, Chapel Hill, USA) in a press release.
In all, 154 patients who had previously failed to respond to treatment with interferon and had elevated ALT levels (≥ 65 U/L) were randomly assigned to receive placebo, or silymarin 420 mg or 700 mg three times daily for 24 weeks. Most of the patients were men (71%) infected with genotype 1 of the virus (91%).
At the end of treatment, 95% of patients had achieved at least 80% adherence to treatment. Equal numbers of patients in the three groups had achieved a serum ALT level of 45 U/L or less, or attained a 50% decline to less than 65 U/L. They represented 3.8%, 4.0%, and 3.8% of patients in the placebo group, and silymarin 420 mg and 700 mg groups, respectively.
Furthermore, there was no significant difference in the decline of serum ALT levels from baseline between treatment groups, nor in serum HCV RNA levels.
It is thought that a third of HCV and cirrhosis patients in the USA have taken silymarin, also known as milk thistle extract, despite a lack of robust evidence for its efficacy. It is also approved as a prescription drug in several countries in Europe and Asia for hepatic disorders.
Studies have shown antiviral, anti-inflammatory and antioxidant effects of silymarin in vitro. However, these were achieved at much greater concentration (20-50 µg/mL) compared with the peak plasma concentrations in the current study (2-2048 ng/mL). This is despite doses being three to five times higher than those normally taken.
However, the herb may have potential benefits when used in other forms. The authors note that these results contrast with those found in a recent trial of silibinin succinate - a silymarin-derived compound not present in the product used in the current study. It has been reported to have greater effects than silymarin, both in vivo and in vitro.
Reporting in the Journal of the American Medical Association, the authors of the current study - which benefited from a cohort representative of the disease population, adequate treatment duration, and a high adherence rate - failed to find any benefit of silymarin in treatment-resistant HCV.
Fried stated that he believes the results are valuable to patients: "I think this information is very important to help patients focus on other ways to maintain liver health and not rely on ineffective remedies."
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