Pharmacokinetics of mycophenolate sodium and comparison with the mofetil formulation in stable kidney transplant recipients.

BACKGROUND AND OBJECTIVES The introduction of mycophenolate mofetil has improved graft survival after organ transplantation; however, its use may be limited by important adverse effects. For overcoming these problems, an enteric-coated formulation of mycophenolate sodium has been developed, but pharmacokinetic data of mycophenolic acid release from this formulation are scanty. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Pharmacokinetic studies in 32 kidney transplant recipients who were given the enteric-coated formulation of mycophenolate sodium (n = 12) or mycophenolate mofetil (n = 20) were performed. The profiles of mycophenolic acid from the two formulations at months 6, 12, 18, and 24 after transplantation were compared. Subsequently, all patients who were receiving the enteric-coated formulation were shifted to mycophenolate mofetil, and the pharmacokinetic evaluations were repeated. RESULTS At month 6 after surgery, aberrant and variable pharmacokinetic curves were found in patients who were given the enteric-coated formulation, whereas those who were taking mycophenolate mofetil had regular mycophenolic acid kinetic profiles. Patients who were taking the enteric-coated formulation had mycophenolic acid time of occurrence for maximum drug concentration that ranged from 0 to 480 min and higher dosage-adjusted mycophenolic acid trough levels compared with patients who were given mycophenolate mofetil. Conversion from the enteric-coated formulation of mycophenolate sodium to mycophenolate mofetil resulted in an improvement of the mycophenolic acid kinetics profiles. CONCLUSIONS Given the emerging clinical benefit of mycophenolic acid monitoring in the transplant setting, therapeutic drug monitoring problems with the enteric-coated formulation of mycophenolate sodium should be taken into account.