Short CommunicationCYP3A5 Genotype Is Not Related to the Intrapatient Variability of Tacrolimus ClearancePashaee, Nilufar BSc*; Bouamar, Rachida PharmD*; Hesselink, Dennis A MD, PhD†; Roodnat, Joke I MD, PhD†; van Schaik, Ron HN PhD‡; Weimar, Willem MD, PhD†; van Gelder, Teun MD, PhD*†Author Information From the Departments of *Hospital Pharmacy, Clinical Pharmacology Unit; †Internal Medicine, Division of Nephrology and Renal Transplantation; and ‡Clinical Chemistry, Erasmus MC, Rotterdam, the Netherlands. Received for publication November 12, 2010; accepted March 15, 2011. The authors declare no conflicts of interest. Dr. D.A. Hesselink has received lecture fees and grant support from Astellas Pharma. Correspondence: Teun van Gelder, MD, PhD, Department of Hospital Pharmacy, Clinical Pharmacology Unit, Room L058, Erasmus MC, PO Box 2040, 3000 CA Rotterdam (e-mail: [email protected]). Therapeutic Drug Monitoring: June 2011 - Volume 33 - Issue 3 - p 369-371 doi: 10.1097/FTD.0b013e31821a7aa3 Buy Metrics Abstract Background: The risk of long-term chronic allograft nephropathy and graft loss after kidney transplantation is increased in patients with a high intrapatient variability of tacrolimus (Tac) clearance. Methods: To test whether this intrapatient variability is associated with an individual's CYP3A5 genotype, we measured the intrapatient variability in Tac clearance in a cohort of 208 kidney transplant recipients treated with Tac and mycophenolate mofetil. Results: Tac dose requirement was significantly higher in patients expressing CYP3A5. However, intraindividual variability of Tac clearance was not related to CYP3A5 genotype. Conclusions: Intraindividual variability in Tac clearance is not related to CYP3A5 genotype. Other factors, including patient adherence, may explain the variability in Tac clearance within an individual patient over time. © 2011 Lippincott Williams & Wilkins, Inc.