Safety, Metabolism, and Antioxidant Activity of Silymarin and Green Tea Extract in Patients With Chronic Hepatitis C

Silymarin and green tea are the two most widely used botanical products used by patients with chronic hepatitis C virus (HCV) infection. A major limitation of prior clinical investigations that may account for lack of efficacy is their use of inadequate customary oral dose regimens. Ongoing Phase II studies utilizing higher than customary doses of silymarin are based on potential disease modifying effects resulting from the potent antioxidant properties of silymarin flavonolignans. Since patients often use more than one herbal product to self-treat their disease, the use of higher than customary doses of silymarin may change silymarin's potential for herbal-herbal interactions. Pharmacokinetic interactions between silymarin and green tea catechins may change their safety/tolerability profiles, and may increase their antioxidant effects through additive or synergistic pharmacodynamic interactions. The objective of this double blind, active placebo controlled, randomized clinical trial is to characterize the pharmacokinetics and to evaluate the safety, tolerability, and antioxidant effects of an herbal cocktail consisting of silymarin and epigallocatechin gallate (EGCG) standardized green tea extract in treatment-naïve patients with chronic HCV infection. This investigation will include two treatment arms that will enroll 15 subjects per arm. Subjects will be randomized to receive in a fixed sequence either: 1) 196.5 mg EGCG followed by the coadministration of 700 mg silymarin; or 2) 700 mg silymarin followed by the coadministration of 196.5 mg EGCG. Each dosing regimen will be administered p.o. every 12 hrs for 12 days. No treatment arm uses high doses for both silymarin and EGCG in a sequence. Depending on the treatment arm, pharmacokinetic studies will be performed on plasma concentrations for six major silymarin flavonolignans and for the green tea catechin, EGCG at the end of 12 days of either silymarin or green tea extract monotherapy (Period 1), and then again after 12 days of silymarin and green tea extract given in combination (Period 2). For each treatment arm, plasma 8F2α-isoprostane concentrations, a measure of oxidative stress, will also be determined at baseline, during each period, and then at follow-up. The results from this investigation will be used to identify doses of silymarin and green tea that can be used together safely for future efficacy trials in patients with different chronic liver diseases.