Pharmacokinetics of enteric coated mycophenolate sodium in lupus nephritis (POEMSLUN).

Abstract

Introduction: Mycophenolate mofetil (MMF) or enteric coated mycophenolate sodium (EC-MPS) and steroids are used for induction and maintenance therapy in severe lupus nephritis (LN). Blood concentrations of mycophenolic acid (MPA), the active metabolite of these drugs varies among LN patients. The objective of this study was to examine whether concentration controlled (CC) dosing (via therapeutic drug monitoring) of EC-MPS result in a higher proportion of participants achieving target exposure of MPA compared to fixed dosing (FD). An additional aim of the study was to evaluate the influence of CC dosing on clinical outcomes.

Methods: Nineteen participants were randomly assigned either to FD or CC group. All the participants were eligible to have free and total measurements of MPA over a period of 8-12 hours on three different occasions. Area under the concentration-time curve between 0 and 12 hours (AUC0-12) was calculated using non-compartmental method. Dose of EC-MPS was titrated according to AUC0-12 in the CC group.

Results: Thirty-two AUC0-12 measurements were obtained from 9 FD and 9 CC participants. Large interpatient variability was observed in both groups but was more pronounced in FD group. There were no significant differences between FD and CC participants in any pharmacokinetic parameters across the study visits except for total C0 (FD 2.0 ± 0.3 mg/L vs. CC 1.1 ± 0.3; p = 0.01) and dose-normalised C0 (FD 2.9 ± 0.2 mg/L/g vs. CC 2.1 ± 0.7 mg/L/g; p = 0.04) at the second visit and total AUC0-12 (FD 66.6 ± 6.0 mg[BULLET OPERATOR]h/L vs. CC 35.2 ± 11.4 mg[BULLET OPERATOR]h/L; p = 0.03) at the third visit. At the first study visit, 33.3% of the FD and 11.1% of the CC participants achieved the target AUC (p = 0.58). From the second visit, none of the FD participants, compared to all the CC participants, achieved target AUC0-12 (p = 0.01). More CC participants achieved remission compared to FD participants (absolute difference of -22.2, 95% confidence interval -0.19-0.55; p = 0.62). The mean free MPA AUC0-12 was significantly lower in those who had complete remission.

Conclusions: CC participants reached target AUC0-12 quicker. Larger studies are required to test clinical efficacy.