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 AUC(0-14) (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.