D-penicillamine-induced myasthenia gravis in primary biliary cirrhosis.

A 62-yr-old woman with recently diagnosed primary biliary cirrhosis was started on D-penicillamine, 250 mg twice daily. Within 9 mo, she developed myasthenia gravis, associated with elevated antiacetylcholine receptor antibody titers and abnormalities of single-fiber electromyography. The D-penicillamine was withdrawn and pyridostigmine bromide was prescribed. The latter drug was slowly reduced, and at the end of 6 mo stopped, after a full recovery by the patient. The clinical response was paralleled by a fall in the antiacetylcholine receptor antibody titer into the normal range and reversal of the previously abnormal single-fiber electromyographic findings. The human leukocyte antigen type of the patient was not that typically associated with classic myasthenia gravis. It is suggested that D-penicillamine-induced myasthenia gravis is due to an independent effect of the drug on the immune system rather than to the unmasking of subclinical myasthenia gravis.