Tripterygium wilfordii Hook F (TwHF) extract offers better symptom relief than sulfasalazine in patients with rheumatoid arthritis, reports Annals of Internal Medicine. (TwHF — also known as “thunder god vine” or “lei gong teng” — is used in traditional Chinese medicine to treat inflammatory conditions.)

U.S. researchers randomized some 120 adults with active rheumatoid arthritis to receive the extract (180 mg) or sulfasalazine (2 g) daily for 24 weeks. Participants were allowed to use stable prednisone dosing (up to 7.5 mg/day) but not disease-modifying antirheumatic drugs.

In intent-to-treat analyses, significantly more patients assigned to TwHF versus sulfasalazine achieved at least a 20% improvement in arthritis symptoms (65% vs. 33%). In analyses limited to the roughly 50% of patients who completed the study, results were similar. Adverse events did not differ between the two groups.

The authors write that three of TwHF’s metabolites — triptolide, tripdiolide, and triptonide — may account for its anti-inflammatory and immunosuppressive effects.