Response to D.M. Marcus's comment on the TRIFRA study (comparison of Tripterygium wilfordii Hook F vs methotrexate in the treatment of active rheumatoid arthritis)

We appreciate the comments of Dr Marcus1 concerning our article on the treatment of patients with rheumatoid arthritis with an extract of Tripterygium wilfordii Hook F (TwHF).2 While we agree that patient safety is of paramount concern, we would like to clarify a number of issues. First, our study did not examine the efficacy of ‘the herb’ TwHF, but rather a pharmaceutical extract of specific parts of the plant. Various extracts of TwHF have been used in traditional Chinese medicine for hundreds of years for various symptoms. Because the plant contains hundreds of components, many of which have biological activity, standardisation has been difficult.3 However, over the past 30 years, intensive work by Chinese and …