The manufacturers say that the concurrent use of
leflunomide and
chloroquine or
hydroxychloroquine has not yet been studied, but it would be expected to increase the risk of serious adverse reactions (haematological
toxicity or hepatotoxicity).
The manufacturers advise avoiding concurrent use. As the active
metabolite of
leflunomide has a long half life of 1 to 4 weeks a washout with colestyramine or activated charcoal should be given if patients are to be switched to other DMARDs.