Mycophenolate mofetil in patients with systemic lupus erythematosus: a prospective pharmacokinetic study

Few studies have assessed the pharmacokinetics of mycophenolic acid (MPA) in non-transplanted patients treated with mycophenolate mofetil (MMF), and little information is available concerning a concentration-effect relationship between the MPA area under the curve (AUC) and the immunological parameters in patients treated for systemic lupus erythematosus (SLE). We evaluated the variations in pharmacokinetics for MPA in patients with SLE and the relationship between MPA-AUC and markers of disease activity. MPA blood concentrations were measured through enzyme-multiplied immunotechnique (T0, T30’, T1h, T2h, T3h and T4h) to determine the MPA AUC0–4h in patients treated with MMF since at least 4 weeks for SLE. Clinical examination, biochemical analyses and immunological analyses were performed on the same day. The relationship between MPA exposure and disease activity markers was assessed. A total of 20 patients were included in the study. The diagnosis of SLE had been made 87 ± 72 months before and patients had been treated with MMF for 31 ± 30 months. Mean dose of MMF on the day of the study was 1600 ± 447 mg/day. Mean MPA AUC0–4h was 28.4 ± 13.6 mg h/L, mean dose-normalised AUC0–4h was 35.5 ± 13.8 mg h/L and mean MPA C0 was 3.1 ± 2.2 mg/L. There was a high correlation between MPA AUC0–4h and MPA C0, ( r = 0.80; P 0–4h tended to be lower in patients who had low complement C3 concentration (0) and immunological disease activity parameters.