Neuromuscular disorders associated with D-penicillamine treatment for rheumatoid arthritis.

Three cases of D-penicillamine (DPA) induced myasthenia gravis (MG) and one case of DPA-induced polymyositis (PM) are reported among four patients suffering from seropositive rheumatoid arthritis. The cumulative doses responsible for the three DPA-induced MG cases amounted respectively to 73, 117 and 467 g. The cumulative dose responsible for the DPA-induced PM case amounted to 465 g. All the patients were HLA DR1. All four cases healed completely after withdrawal of DPA. The aetiology of the cases is discussed and the literature is reviewed. These cases represent further instances of DPA-induced neuromuscular disorders.