title: Clinical efficacy and toxicity profile of tacrolimus and mycophenolic acid in relation to combined long-term pharmacokinetics in de novo renal allograft recipients.
abstract: BACKGROUND
  Tacrolimus and mycophenolate mofetil are effective drugs characterized by specific toxicity profiles that may compromise their long-term use in renal transplant recipients. Clinicians, therefore, need reliable drug monitoring tools for relating efficacy and toxicity to drug exposure. Study design We conducted a prospective 12-month pharmacokinetic study of tacrolimus and mycophenolic acid in 100 de novo recipients. The aim was to examine whether tacrolimus and mycophenolic acid exposure parameters (predose trough blood concentration [C(0)], area under the concentration curve from 0 to 12 hours [AUC(0-12)], maximum blood or plasma concentration [C(max)], and dose) would reflect clinical efficacy and toxicity at different time points after transplantation (7 days, 6 weeks, and 3, 6, and 12 months).
  
  
  RESULTS
  Initially, after grafting, the tacrolimus AUC(0-12) was higher in recipients with infection (P =.01 on day 7, P =.02 at week 6), whereas the mycophenolic acid AUC(0-12) was not different. There was no difference in tacrolimus exposure between patients who had arterial hypertension or hyperlipidemia and those who did not. Patients with tacrolimus nephrotoxicity received a higher drug dose (P =.03) and had higher drug clearance (P =.02). From 3 months, recipients with anemia or leukopenia had higher mycophenolic acid AUC(0-12) (anemia, P =.03 at month 3 and P =.01 at month 12; leukopenia, P =.01 at month 3 and P =.04 at 1 year) and C(0) (anemia, P =.001 at month 3 and P =.001 at month 12; leukopenia, P =.01 at month 3 and P =.04 at 1 year). Finally, for recipients who did not simultaneously have a target tacrolimus AUC(0-12) of 150 ng x h/mL and a mycophenolic acid AUC(0-12) of 45 mg x h/L by day 7, the incidence of acute rejection tended to be higher (26.3%) compared with patients who reached both target values (7.7%) (P =.07).
  
  
  CONCLUSIONS
  Pharmacokinetic exposure parameters of tacrolimus and mycophenolic acid are related to specific drug-induced side effects in a time-dependent fashion. In addition, this study has provided a conceptual basis for defining a combined target therapeutic window for tacrolimus and mycophenolic acid based on sparse AUC(0-12) measurements.
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, Belgium. Dirk.Kuypers@uz.kuleuven.ac.be
authors.forename: Dirk R J
authors.initials: DR
authors.lastname: Kuypers
authors.forename: Kathleen
authors.initials: K
authors.lastname: Claes
authors.forename: Pieter
authors.initials: P
authors.lastname: Evenepoel
authors.forename: Bart
authors.initials: B
authors.lastname: Maes
authors.forename: Yves
authors.initials: Y
authors.lastname: Vanrenterghem
mesh_terms: D019540:Area Under Curve; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D003404:Creatinine / Q000097:blood; D004359:Drug Therapy, Combination; D005260:Female; D005858:Germany; D006084:Graft Rejection; D006801:Humans; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D011183:Postoperative Complications; D011446:Prospective Studies; D012709:Serum Albumin; D016559:Tacrolimus / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D014280:Triglycerides / Q000097:blood
chemical_list: D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D012709:Serum Albumin; D014280:Triglycerides; D002784:Cholesterol; D003404:Creatinine; D009173:Mycophenolic Acid; D016559:Tacrolimus