In the most rigorous trial to date, oral silymarin was not superior to placebo in decreasing disease activity.
Silymarin is a botanical extract of milk thistle commonly used by patients with liver disease. In vitro studies have demonstrated antiviral, anti-inflammatory properties of silymarin in hepatitis C virus (HCV) replicon systems. However, the few efficacy studies conducted in patients with chronic HCV infection have produced mixed results.
In a new multicenter, double-blind, placebo-controlled efficacy trial, investigators randomized 154 patients (median age, 54; 71% men) with chronic HCV infection who previously failed interferon-based therapy to receive 420 mg of silymarin, 700 mg of silymarin, or placebo three times daily for 24 weeks. The two oral doses of pure silymarin were determined by earlier dose finding studies and were three to five times higher than concentrations used in previous studies. The primary endpoint was a serum alanine aminotransferase (ALT) level of 45 U/L or a 50% reduction from baseline ALT to a level <65 U/L. Secondary endpoints included HCV RNA levels and quality-of-life indicators.
After 24 weeks of treatment, only two patients in each group achieved the primary endpoint. The mean decline in ALT levels at the end of treatment, the mean change in HCV RNA levels, and the quality-of-life indicators did not differ among the three groups.
Comment: This trial definitively demonstrates that silymarin, even at three to five times the typical dose, is ineffective in treating patients with chronic HCV infection. Unlike previous trials, this study used a pure, quantifiable formulation of silymarin and well-defined outcomes, its cohort was large and representative of the patient population, the treatment period was sufficiently long, and both medication and visit adherence rates were high. Clinicians should quote this study when addressing patients’ questions regarding the use of milk thistle for treating HCV infection.
Source: Journal Watch Gastroenterology