Clinical course of bucillamine-induced nephropathy in patients with rheumatoid arthritis.

Background: Bucillamine, a disease-modifying antirheumatic drug widely prescribed in Japan, is reported to be a cause of proteinuria. However, to date, the clinical course of the nephropathy associated with the use of bucillamine has not been described in detail.

Methods: We analyzed renal biopsy findings from 10 patients with rheumatoid arthritis and concomitant bucillamine-induced nephropathy. Each patient was followed up until proteinuria had resolved.

Results: Proteinuria appeared 2-11 months after the initiation of the treatment with bucillamine. Nine patients, who stopped bucillamine treatment immediately (within 3 months) after the onset of proteinuria, were diagnosed as having stage I membranous nephropathy. Only one patient, who used bucillamine for 9.5 months after the onset of proteinuria, was diagnosed as having stage II membranous nephropathy. In all patients with stage I membranous nephropathy, the proteinuria disappeared within 7 months after they stopped bucillamine treatment. On the other hand, in the patient with stage II membranous nephropathy, the proteinuria persisted for 14 months after the use of bucillamine was stopped. In all the patients, the proteinuria resolved completely without deterioration of renal function. None of the patients has experienced recurrence of proteinuria.

Conclusions: In patients with proteinuria induced by treatment with bucillamine, membranous nephropathy is the most common disorder. Immediate withdrawal of bucillamine results in prompt and complete resolution of proteinuria without deterioration of renal function.Bucillamine, a disease-modifying antirheumatic drug widely prescribed in Japan, is reported to be a cause of proteinuria. However, to date, the clinical course of the nephropathy associated with the use of bucillamine has not been described in detail.