To examine the safety and efficacy of an extract of Tripterygium wilfordii Hook F (TWHF) in the treatment of patients with rheumatoid arthritis (RA).


An ethanol/ethyl acetate extract from the roots of TWHF was prepared and used in a prospective, double-blind, placebo-controlled study in patients with longstanding RA in whom conventional therapy had failed. Patients were randomly assigned to receive either placebo or low-dose (180 mg/day) or high-dose (360 mg/day) extract for 20 weeks, followed by an open-label extension period. Clinical responses were defined as 20% improvement in disease activity according to the American College of Rheumatology criteria. Side effects were actively queried and recorded at each visit.


A total of 35 patients were enrolled in the trial; 21 patients completed the 20-week study. One patient from each group withdrew because of side effects. Twelve, 10, and 10 patients in the placebo, low-dose, and high-dose groups, respectively, completed at least 4 weeks of treatment. Of these patients, 8 and 4 in the high-dose and low-dose groups, but none in the placebo group, met criteria for clinical response. Four, 4, and 7 patients in the placebo, low-dose, and high-dose groups, respectively, were enrolled in the open-label extension; of these, 2, 4, and 5 patients, respectively, met criteria for clinical response. The most common side effect was diarrhea, which caused 1 patient in the high-dose group to withdraw from the trial. No patients withdrew because of adverse events during the open-label extension.


The ethanol/ethyl acetate extract of TWHF shows therapeutic benefit in patients with treatment-refractory RA. At therapeutic dosages, the TWHF extract was well tolerated by most patients in this study.