Purpose: To examine whether the monitoring of cyclosporine (CsA) blood concentrations is of benefit in CsA microemulsion pre-concentrate (MEPC) therapy for myasthenia gravis (MG).
Methods: We measured CsA blood concentrations both 2 h after administration (C2) and immediately before administration (C0) and examined associations with changes to clinical parameters in 20 MG patients treated with CsA MEPC in an unblinded, 6-month prospective open trial.
Results: Initial dose of CsA MEPC (4.7 +/- 0.5 mg/kg/day) provided both high C2 levels and safe C0 levels. Disease severity, daily dose of prednisolone, acetylcholine receptor-antibody titre levels and levels of interleukin-2 production by peripheral blood mononuclear cells were significantly reduced following treatment with CsA MEPC. A significant correlation existed between C2 levels following the initial dose and clinical improvement in responder MG patients. C0 levels were significantly higher in patients who exhibited increased serum creatinine or hypertension compared with patients free from side effects. Body mass index of individual patients was significantly correlated with C0 level, and may thus offer a useful marker to predict C0 levels.
Discussion: CsA MEPC was effective at suppressing symptoms and T-cell-dependent pathogenesis of MG, and monitoring of C2 and C0 levels can be useful to estimate efficacy and safety of the drug.