Monitoring trough plasma concentrations of mycophenolate mofetil in patients with uveitis

Mycophenolate mofetil (MMF) has been used successfully in patients with various forms of uveitis not responsive to other immunosuppressants. Nevertheless, for these patients neither recommendations for optimal dosage of MMF nor data concerning drug exposure of MMF are available.

To describe the results of the therapeutic drug monitoring (TDM) of MMF trough concentrations in a cohort of patients with uveitis, with the aim of optimizing the dosage of this drug, by maintaining a target concentration to achieve adequate immunosuppression with a minimal risk of therapeutic failure or toxicity.

This study describes the results of monitoring trough plasma concentrations of MMF in 12 patients with uveitis during a mean period of 21.4 months. Patients included one with Stevens-Johnson syndrome, one with Graves-Basedow's disease, one with Behcet's disease, one with idiopathic thrombocytopenic purpura and the rest with idiopathic uveitis. All patients were treated with steroids and additional therapy prior to treatment with MMF.

Pharmacokinetic monitoring of mycophenolic acid (MPA) was performed with 108 trough plasma samples using an EMIT assay. Mean daily MMF dose was 24.5 +/- 6.3 mg/kg and mean trough MPA concentration was 2.9 +/- 1.9 microg/mL. Therapy was effective in 10 patients (83%). There were few side-effects: diarrhoea, excitement, agitation and cough that disappeared with daily dose reduction of MMF.

MMF was effective in the majority of patients with uveitis with an acceptable profile of side-effects. TDM of MMF in patients with uveitis is clinically practicable and may help to optimize individual immunosuppressive therapy. We estimated that MMF dosages in the range of 0.5-1.5 g/day might be sufficient for treating uveitis and we recommend an initial target range of 2-4 microg/mL, which included 50% of our results. Randomized controlled trials are essential to confirm the efficacy of MMF in uveitis.