Pharmacokinetics of Mycophenolic Acid after Intravenous Administration of Mycophenolate Mofetil to Healthy Cats

BACKGROUND Mycophenolate mofetil (MMF), the prodrug of mycophenolic acid (MPA), is becoming increasingly popular as an alternative immunosuppressant in feline medicine. Pharmacokinetic information is not available for cats. OBJECTIVE The purpose of this study was to determine whether MMF is biotransformed into the active metabolite MPA and to evaluate the disposition of MPA after a 2-hour constant rate intravenous (IV) infusion of MMF in healthy cats. ANIMALS Healthy cats (n = 6). METHODS This was a prospective pilot study. All cats were administered MMF at 20 mg/kg every 12 hours over a 2-hour constant rate infusion for 1 day. The concentrations of MPA and its derivatives in blood were determined using a validated UHPLC-UV method. RESULTS All cats biotransformed MMF into MPA. The mean AUC0-14 h ranged from 6 to 50 h*mg/L after IV dosing of MMF. Transient large bowel diarrhea was recorded in 2 of 6 cats after medication administration. CONCLUSION AND CLINICAL IMPORTANCE The disposition of MPA in plasma was highly variable, which could result in high interindividual variability in the safety and efficacy of treatment with MMF in cats.