Conversion From Mycophenolate Mofetil to Enteric-Coated Mycophenolate Sodium in Maintenance Renal Transplant Recipients Receiving Tacrolimus: Clinical, Pharmacokinetic, and Pharmacodynamic Outcomes

Abstract

Mycophenolic acid (MPA) pharmacokinetics using the mycophenolate mofetil (MMF) formulation are known to differ between patients receiving tacrolimus or cyclosporine, but only limited data exist concerning concomitant use of tacrolimus and enteric-coated mycophenolate sodium (EC-MPS). In this six-month, multicenter, open-label, single-arm trial, 63 maintenance renal transplant patients receiving tacrolimus were converted from mycophenolate mofetil (MMF) to EC-MPS. MPA concentration-time profiles in 21 patients showed that MPA exposure was similar with MMF or EC-MPS (mean area under the curve 39.9+/-11.6 microg x h/mL versus 43.7+/-17.4 microg x h/mL at day 14 post-conversion). Median time to peak concentration was 0.5 hr with MMF and 1.5 hr with EC-MPS. Inosine monophosphate dehydrogenase (IMPDH) activity was almost identical: area under the enzyme activity time curve (AEC) was 124.2+/-32.0 nmol x h/mg prot/h with MMF and 130.3+/-36.6 nmol x h/mg prot/h with EC-MPS at 14 days post-conversion; average daytime IMPDH activity was 10.3+/-2.7 nmol/h/mg protein and 10.9+/-2.7 nmol/h/mg protein, respectively. Maximal daytime inhibition of IMPDH activity was 67% with MMF and 62% with EC-MPS at day 14. One patient (1.6%) experienced mild biopsy-proven acute rejection. No graft losses or deaths occurred. Renal function remained stable (mean calculated creatinine clearance 70.6+/-26.8 mL/min with MMF and 68.8+/-25.4 mL/min six months post-conversion). Adverse events or infections with a suspected relation to EC-MPS occurred in 12 patients (19%). Four patients discontinued EC-MPS due to adverse events or infections. MMF and EC-MPS are associated with similar MPA exposure and equivalent pharmacodynamic effect. Conversion of tacrolimus-treated maintenance renal transplant patients from MMF to EC-MPS is safe and well-tolerated and does not compromise therapeutic efficacy.