Successful treatment of a patient with severe refractory myasthenia gravis using mycophenolate mofetil

Mycophenolate mofetil is an immunosuppressive agent that inhibits the de novo pathway of guanosine nucleotide synthesis critical for B- and T-lymphocyte proliferation.1 It is absorbed rapidly and undergoes presystemic metabolism to mycophenolic acid-a potent, selective, noncompetitive, and reversible inhibitor of inosine monophosphate dehydrogenase.2 We present a patient with severe refractory myasthenia gravis (MG) who experienced an excellent response to mycophenolate mofetil. A 14-year-old girl initially noticed dysarthria on sustained speech. A year later she experienced intermittent ptosis; face, neck, and limb weakness; drooling; difficulty chewing and swallowing; and shortness of breath. Acetylcholine receptor antibody levels, Tensilon (Zeneca Pharmaceuticals; Wilmington, DE) test, and repetitive nerve stimulation were all positive and consistent with the diagnosis of MG. The patient was placed on escalating doses of pyridostigmine without benefit. She suffered a cholinergic crisis on pyridostigmine, 1,800 mg/d, that required hospitalization and mechanical ventilation. Pyridostigmine was then discontinued. Pyridostigmine subsequently was retried several times over the ensuing years but …