title: Pharmacokinetics of mycophenolic acid, tacrolimus and sirolimus after gastric bypass surgery in end-stage renal disease and transplant patients: a pilot study.
abstract: BACKGROUND
  Promising data regarding the safety and efficacy of gastric bypass surgery (GBS) as an option to address obesity in the transplant population are emerging. The data lack on how GBS may alter the pharmacokinetics (PK) of modern immunosuppression. The objective of this study was to describe the alterations in the PK of modern immunosuppressants and the GBS population.
  
  
  METHODS
  Data are presented on six subjects who participated in this trial--four were on dialysis and two were renal transplant recipients. Dialysis-dependent bypass subjects received a single dose of 6 mg of sirolimus, two 4-mg doses of tacrolimus and two 1000-mg doses of mycophenolate mofetil (MMF) over the 24-h study period. Transplant recipients continued their current regimen. Maximum plasma concentration (C(max)), time to reach the maximum plasma concentration (T(max)) and the area under the plasma concentration vs. time curve (AUC(0-12) and AUC(0-infinity) where appropriate) were calculated for tacrolimus, sirolimus, mycophenolic acid (MPA) and mycophenolic acid glucuronide (MPAG).
  
  
  RESULTS
  Significant inter-patient variability in the C(max), T(max) and AUC of tacrolimus, sirolimus MPA and MPAG was observed. A notable difference in the AUC:dose ratio for tacrolimus was seen when comparing data with published data in the non-bypass population. Similar differences in PK were seen with sirolimus, MPA and MPAG.
  
  
  CONCLUSIONS
  When comparing the PK of sirolimus, tacrolimus, MPA and MPAG to published PK data in the non-bypass population, significant differences are observed. It is likely that transplant recipients with GBS would need higher doses of tacrolimus, sirolimus and MMF to provide similar exposure to a non-bypass patient.
authors.affiliation: University of Cincinnati, Department of Surgery, Cincinnati, OH 45267-0585, USA.
authors.forename: Christin C
authors.initials: CC
authors.lastname: Rogers
authors.forename: Rita R
authors.initials: RR
authors.lastname: Alloway
authors.forename: J Wesley
authors.initials: JW
authors.lastname: Alexander
authors.forename: Michael
authors.initials: M
authors.lastname: Cardi
authors.forename: Jennifer
authors.initials: J
authors.lastname: Trofe
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Vinks
mesh_terms: D000328:Adult; D015390:Gastric Bypass; D020719:Glucuronides / Q000493:pharmacokinetics; D006801:Humans; D007166:Immunosuppressive Agents / Q000493:pharmacokinetics*; D007676:Kidney Failure, Chronic / Q000378:metabolism*; D016030:Kidney Transplantation; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000493:pharmacokinetics*; D010865:Pilot Projects; D006435:Renal Dialysis; D020123:Sirolimus / Q000008:administration & dosage / Q000493:pharmacokinetics*; D016559:Tacrolimus / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D020719:Glucuronides; D007166:Immunosuppressive Agents; C113145:mycophenolic acid glucuronide; D009173:Mycophenolic Acid; D020123:Sirolimus; D016559:Tacrolimus