Leflunomide

Leflunomide is a drug I've seen used with increasing frequency in the renal transplant world. Marketed under the trade name "Arava", it is an immunomodulatory agent which works by inhibition of the enzyme dihydroorotate dehydrogenase, one of the important enzymes in pyramidine synthesis. It has immunosuppressive properties which have proven useful in the treatment of autoimmune diseases such as rheumatoid arthritis and psoriatic arthritis. It also has been shown to have antiviral activity against both BK virus and CMV virus, which is why I've seen this adopted in the transplant community: there are very few effective treatments demonstrated thus far which have anti-BK virus activity, and we are using leflunomide to treat a patient on our service currently with gancyclovir-resistant CMV infection.