New Zealand. According to a recent Prescriber Update article available from Medsafe, New Zealand, serious multi-system adverse effects are possible with leflunomide, an effective disease modifying agent for rheumatoid arthritis. The adverse reactions associated with the use of this drug involve haematological, hepatic, immune, dermatological and respiratory systems. International reports include liver failure (15 cases, nine with fatal outcome), neutropenia, thrombocytopenia, thrombo-cytosis, severe pancytopenia, Stevens Johnson syndrome, bullous eruptions and skin necrosis, interstitial pneumo-nitis and pulmonary infiltration and infections due to immune response impairments including sepsis. Post-marketing experience with leflunomide estimates the frequency of severe hepatic, dermatological, respiratory, haematological and infection reactions as being very rare (less than 1 in 10 000) and for blood dyscrasias as being rare (between 1 in 1000 and 1 in 10 000). According to the article, the long half-life of leflunomide may delay resolution of some of the reactions but regular monitoring and patient education of early warning signs (e.g. easy bruising, tiredness, pallor, skin lesions, shortness of breath etc.) can reduce morbidity. To minimize the risk of serious blood and liver adverse reactions, all patients taking leflunomide should have their haematological and liver function monitored. Pretreatment baseline values should be established for these functions first before starting therapy, every month after initiating therapy for the first six months and, every six to eight weeks thereafter. Ongoing monthly monitoring is recommended if methotrexate is used concurrently.
Prescriber Update Articles, April 2004. Available from URL: http://www.medsafe.govt.nz/Profs/PUarticles/Arava.htm