title: Effects of gastric emptying on oral mycophenolic acid pharmacokinetics in stable renal allograft recipients.
abstract: BACKGROUND
  * Strategies that are more elaborate than measuring predose plasma concentrations are required for the therapeutic monitoring of mycophenolic acid (MPA). * Previous studies in healthy subjects and diabetes patients have suggested that MPA pharmacokinetics are influenced by gastric emptying, but this has not been demonstrated directly.
  
  
  CONCLUSIONS
  * This study has investigated the relationship between gastric emptying, measured directly (using the (14)C octanoate and (13)C glycine breath tests) and the steady-state plasma concentration-time profile of MPA. * Delayed gastric emptying was associated with a longer t(max) and lower C(max), but total exposure to MPA was not affected. * The findings suggest that it could be misleading to rely fully on short-term (<2 h) limited sampling strategies for MPA therapeutic monitoring in recipients with gastric emptying disorders, the latter occurring relatively frequently in solid organ transplantation.
  
  
  OBJECTIVE
  To investigate the effect of gastric emptying on the pharmacokinetics of mycophenolic acid (MPA) in renal transplant patients.
  
  
  METHODS
  We assessed the effect of gastric emptying on the disposition of MPA in 27 stable renal allograft recipients at 2 years after transplantation. Gastric emptying was measured by the (14)C-octanoate and (13)C-glycine breath test.
  
  
  RESULTS
  Delayed gastric emptying was associated with a significantly longer MPA t(max)[1.0 (0.33-2.0) h vs. 0.5 (0.33-1.0) h; mean difference 0.39 h, 95% confidence interval (CI) 0.03, 0.75; P = 0.0289] and with a significant decrease in the maximum MPA concentration after dosing [10.6 (6.5-21.3) mg l(-1)vs. 20.1 (10.7-28.5) mg l(-1); mean difference 6.5 mg l(-1), 95% CI 2.1, 10.9; P = 0.0075]. Despite the substantial effect of delayed gastric emptying rates on MPA C(max) and t(max), total dose-interval exposure, measured by the MPA AUC(0-4), was not affected by the rate of gastric emptying [20.4 (13.9-43.0) mg h(-1) l(-1)vs. 22.4 (13.1-29.8) mg h(-1) l(-1)].
  
  
  CONCLUSIONS
  Delayed gastric emptying was associated with a slower absorption of MPA, a longer time to reach peak concentrations and lower maximum concentrations. These effects should be taken into account when validating limited (<2 h) sampling strategies to estimate total MPA exposure, which could be unreliable when monitoring patients with gastric emptying disorders.
authors.affiliation: Department of Nephrology and Renal Transplantation, University Hospitals Leuven, Belgium.
authors.forename: Maarten
authors.initials: M
authors.lastname: Naesens
authors.forename: Kristin
authors.initials: K
authors.lastname: Verbeke
authors.forename: Yves
authors.initials: Y
authors.lastname: Vanrenterghem
authors.forename: Dirk
authors.initials: D
authors.lastname: Kuypers
mesh_terms: D000328:Adult; D000368:Aged; D001944:Breath Tests / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D005746:Gastric Emptying; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood*; D016030:Kidney Transplantation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009173:Mycophenolic Acid / Q000097:blood*; D011184:Postoperative Period
chemical_list: D007166:Immunosuppressive Agents; D009173:Mycophenolic Acid