Pharmacokinetic and pharmacodynamic alterations in the Roux-en-Y gastric bypass recipients

Sweta Tandra, Naga Chalasani, David R. Jones, Samer Mattar, Stephen D. Hall, Raj Vuppalanchi

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


OBJECTIVE:: We conducted a pharmacokinetic (PK) study and a pharmacodynamic (PD) study to assess whether Roux-en-Y gastric bypass (RYGB) surgery is associated with significant changes to PK and PD of oral medications. BACKGROUND:: The effect of RYGB on oral drug disposition is not well understood. METHODS:: An oral cocktail of probe drugs for major drug-metabolizing enzymes (caffeine, tolbutamide, omeprazole, dextromethorphan, and oral and intravenous midazolam) was administered to 18 RYGB recipients and 18 controls. Timed blood and urine samples were obtained for PK analyses. Forty mg of oral furosemide was administered to 13 RYGB recipients and 14 controls, and urine and blood samples were collected for assessing furosemidePK, and urine volume and urine sodium excretion for PD analyses. RESULTS:: Compared with controls, the RYGB group had significantly lower time to maximum plasma concentration (tmax) for caffeine (0.58 ± 0.5 vs 2.1 ± 2.2 hours, P < 0.0001), tolbutamide (1.4 ± 1.8 vs 2.1 ± 2.2 hours, P = 0.0001), omeprazole (1.1 ± 1.1 vs 4.4 ± 1.3 hours, P < 0.0001), and oral midazolam (0.5 ± 0.2 vs 0.7 ± 0.4 hours, P < 0.01). However, maximum plasma concentration, half-life, area under the curve, and oral bioavailability were not different. Compared with controls, the RYGB group had brisk natriuresis, with significantly lower tmax for urine sodium (1.3 ± 0.5 vs 3.1 ± 2.3 hours, P < 0.02) and correspondingly lower tmax for furosemide (1.8 ± 0.3 vs 4.2 ± 1.2 hours, P = 0.006). However, 6-hour urine sodium and 6-hour urine volume were not different between the two groups. CONCLUSIONS:: RYGB recipients have significantly shorter tmax for the studied orally administered medications, but otherwise no other significant changes in PK were reported.

Original languageEnglish (US)
Pages (from-to)262-269
Number of pages8
JournalAnnals of surgery
Issue number2
StatePublished - Aug 2013


  • CYP3A
  • drug metabolism
  • furosemide
  • gastric bypass
  • oral cocktail

ASJC Scopus subject areas

  • Surgery


Dive into the research topics of 'Pharmacokinetic and pharmacodynamic alterations in the Roux-en-Y gastric bypass recipients'. Together they form a unique fingerprint.

Cite this