Leflunomide and rheumatoid interstitial lung disease

Abstract

Interstitial lung disease(ILD) is one of the common extra-articular manifestations of rheumatoid arthritis(RA).Its incidence in RA is 7.7%,and the prognosis is poor.Leflunomide is one of the commonly used drugs for RA,but there are more and more reports about leflunomide caused interstitial pneumonia.Then,should leflunomide be used when RA is complicated with ILD? However,It has been reported that leflunomide can be an effective treatment for RA patient who already sufferred from lung disease[including ILD caused by methotrexate(MTX)],and no adverse drug reaction or pulmonary exacerbation was observed.So,leflunomide could be used as a replacement therapy in patients with MTX related ILD.The safety of leflunomide in treatment of RA was relatively approved in China, but the reports on leflunomide induced ILD were not rare recently outside of China.A cohort study performed in Canada reported that the risk of ILD was increased in RA patients treated with leflunomide(adjusted RR 1.9),but it was not elevated in patients with no previous history of MTX use or ILD(adjusted RR1.2).Japanese scholars proposed that leflunomide application should be prohibited or require careful consideration in elderly male RA patients with history of ILD or smoking.Pulmonary function responsed to leflunomide adversely in an ethnic group dependent manner.Genetics testing might be the key to find the answer.Although leflunomide had a potential risk of causing ILD,meta-analysis indicated satisfactory therapeutic effects and safety of leflunomide for RA.For RA patients with preexisting pulmonary disorders,leflunomide application requires careful consdideration and CT scanning should be monitored regularly.