Abstract
Tacrolimus, a potent immunosuppressive agent, has recently become available for the treatment of myasthenia gravis (MG). However, few reports have evaluated the usefulness of tacrolimus in the elderly and in intractable MG classified as Osserman's grade IIb or higher. In this study, we examined the effects of tacrolimus in two patients with postthymectomy Osserman's grade III and IIb MG. The effects of tacrolimus were evaluated using the modified quantitative MG score (QMG score) and anti-acetylcholine receptor antibody (AChRAb) titer. Patient 1 was a 39-year-old woman with Osserman grade III MG. Her MG score improved after tacrolimus administration (3 mg/day), allowing gradual decreases in the doses of prednisolone and pyridostigmine because of improvement in MG symptoms. The AChRAb titer also decreased from 100.0 to 25.7 nmol/l during tacrolimus treatment. The concentrations of tacrolimus in whole blood ranged from 5.5 to 8.2 ng/ml during treatment. Patient 2 was a 68-year-old man diagnosed with Osserman grade IIb MG. After the initiation of tacrolimus treatment, dysphagia improved dramatically, and he was able to swallow food without a nasal feeding tube. The AChRAb titer decreased from 42.4 to 23.4 nmol/l during the treatment period. The concentration of tacrolimus in whole blood was 7.0 ng/ml 6 days after the initiation of treatment. These findings suggest that tacrolimus is effective in intractable and elderly MG patients.
