title: A comparison of the effect of ciclosporin and sirolimus on the pharmokinetics of mycophenolate in renal transplant patients.
abstract: OBJECTIVE
  To compare the pharmacokinetics of mycophenolic acid when given with either ciclosporin or sirolimus, and investigate in vitro the potential effect of ciclosporin, sirolimus, tacrolimus and everolimus on mycophenolic acid metabolism.
  
  
  METHODS
  In renal transplant patients given mycophenolate mofetil in combination with ciclosporin (n = 19) or sirolimus (n = 12), concentration-time profiles of mycophenolic acid, mycophenolic-acid-phenyl-glucuronide, mycophenolic-acid-acyl-glucuronide and mycophenolic-acid-phenyl-glucoside were determined at one month post-transplant. The effect of immunosuppressive drugs on mycophenolic acid glucuronidation and glycosylation was investigated in vitro using human liver microsomes.
  
  
  RESULTS
  The mean mycophenolic acid AUC(0-9 h) in the sirolimus group was 44.9 mg h(-1) L(-1) (95% CI: 34.7-55.1), vs. 30.5 mg h(-1) L(-1) (95% CI: 25.4-35.6) in the ciclosporin group, corresponding to 1.5-fold dose-normalized difference (95% CI: 1.1-1.9; P < 0.05). In addition, the metabolite/mycophenolic acid AUC(0-9 h) ratios were significantly higher in patients cotreated with ciclosporin than with sirolimus, giving values of 1.8-fold (95% CI: 1.3-2.3; P = 0.0009), 2.6-fold (95% CI: 2.0-3.3; P < 0.0001) and 4.3-fold (95% CI: 2.6-6.0; P = 0.0016) for mycophenolic-acid-phenyl-glucuronide, mycophenolic-acid-acyl-glucuronide and mycophenolic-acid-phenyl-glucoside, respectively. In vitro, none of the immunosuppressive drugs tested inhibited mycophenolic acid metabolism.
  
  
  CONCLUSIONS
  Patients taking mycophenolate mofetil and sirolimus experience a higher exposure to mycophenolic acid and a lower exposure to mycophenolic acid metabolites than those being treated with mycophenolate mofetil and ciclosporin. This interaction is probably not caused by inhibition of mycophenolic acid glucuronidation or glycosylation, but is more likely to be due to the influence of ciclosporin on the excretion of mycophenolic acid metabolites into bile.
authors.affiliation: Laboratory of Pharmacology, Faculty of Medicine, University of Limoges, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Picard
authors.forename: Aurélie
authors.initials: A
authors.lastname: Prémaud
authors.forename: Annick
authors.initials: A
authors.lastname: Rousseau
authors.forename: Yannick
authors.initials: Y
authors.lastname: Le Meur
authors.forename: Pierre
authors.initials: P
authors.lastname: Marquet
mesh_terms: D000328:Adult; D000368:Aged; D016572:Cyclosporine / Q000494:pharmacology* / Q000627:therapeutic use; D004347:Drug Interactions; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000627:therapeutic use; D020123:Sirolimus / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D007166:Immunosuppressive Agents; D016572:Cyclosporine; D009173:Mycophenolic Acid; D020123:Sirolimus