title: Pharmacokinetics of tacrolimus according to body composition in recipients of kidney transplants.
abstract: BACKGROUND
  Currently, the dosage of tacrolimus used after transplantation is based on the patient's body weight. However, there is a low correlation between body weight and body composition in kidney transplant recipients. In this study, we evaluate the pharmacokinetics of tacrolimus according to body composition in 18 Korean kidney transplant recipients with stable graft function.
  
  
  METHODS
  Body composition parameters were calculated using bioelectrical impedance analysis. Pharmacokinetic profiles were determined 0, 1, 2, 3, and 4 hours after treatment with tacrolimus and were compared between high- and low-level median body composition groups. The values of C0, C1, C2, C3, and C4 were used in determining an abbreviated area under the curve (AUC) for tacrolimus.
  
  
  RESULTS
  The mean body mass index (BMI) and body composition values were as follows: BMI, 24.3 kg/m(2); lean mass, 49.8 kg; and fat mass, 17.4 kg. There were no statistical differences in pharmacokinetic profiles between groups with different BMIs. However, the C0 and C4 in the high-fat group were significantly elevated compared with those of the low-fat group (P=0.024 and 0.031, respectively). Furthermore, the C0, C2, C3, and C4 and the AUC were significantly different between the two lean mass groups (P=0.007, 0.038, 0.047, 0.015, and 0.015, respectively). Other variables, such as waist circumference and arm muscle circumference, did not differentiate between the pharmacokinetic profiles of tacrolimus.
  
  
  CONCLUSIONS
  Taken together, these data suggest that tacrolimus dose monitoring based on body composition may provide adequate dosage leading to favorable long-term outcomes.
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Seung Seok
authors.initials: SS
authors.lastname: Han
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Do Hyoung
authors.initials: DH
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Su Mi
authors.initials: SM
authors.lastname: Lee
authors.affiliation: Department of Clinical Pharmacy, Seoul National University College of Pharmacy, Seoul, Korea.
authors.forename: Na Young
authors.initials: NY
authors.lastname: Han
authors.affiliation: Department of Clinical Pharmacy, Seoul National University College of Pharmacy, Seoul, Korea.
authors.forename: Jung Mi
authors.initials: JM
authors.lastname: Oh
authors.affiliation: Department of Surgery, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jongwon
authors.initials: J
authors.lastname: Ha
authors.affiliation: Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea; Kidney Research Institute, Seoul National University, Seoul, Korea.
authors.forename: Yon Su
authors.initials: YS
authors.lastname: Kim
keywords: Adipose tissue; Body composition; Muscles; Pharmacokinetics; Tacrolimus