Bucillamine (BCL), a treatment for rheumatoid arthritis, occasionally causes proteinuria. Renal specimens are reported to show segmental granular deposition of immunoglobulin G, associated with membranous nephropathy. Long-term course and optimal treatment have remained unknown, and were investigated here.
We examined clinical records of 400 patients treated with BCL for rheumatoid arthritis, at our hospital from 1998 to 2003, finding 17 with proteinuria and biopsy-proven BCL-induced nephropathy.
In all 17 patients, proteinuria resolved without loss of renal function between 3 and 85 months after discontinuing BCL (14.1 +/- 3.4). The only factor influencing time to remission was pathologic stage of membranous nephropathy (stage I vs. stage II or III: 11.5 +/- 4.8 vs. 21.6 +/- 3.3 months; p = 0.02). Maximal proteinuria, total amount of BCL, BCL exposure time, and use of prednisolone or other immunosuppressant agents did not significantly influence time until remission.
The most important therapeutic step in treating BCL-induced nephropathy is to discontinue BCL. Prednisolone or other immunosuppressant agents might not be effective.