Effect of Obesity and Roux-En-Y Gastric Surgery on Omeprazole Pharmacokinetics

: The prevalence of obesity is increasing globally. The principal aim was to evaluate whether gastric bypass surgery modifies the bioavailability and pharmacokinetic (PK) parameters of omeprazole. Methods: Controlled, open-label, bioavailability clinical trial in patients undergoing Roux-en-Y gastric bypass (RYGB). Healthy patients with obesity (body mass index >35) were included and assessed for omeprazole PKs before and after RYGB (1 and 6 months). PK sampling was done at baseline and several times up to 12 h after drug dosing. Pre- and post-surgery parameters were compared using paired ANOVA or Wilcoxon tests, and control versus cases using ANOVA or Mann-Whitney tests. Given the post-surgery change in body weight, parameters were corrected by dose/body weight. Results: Fourteen case and 24 control subjects were recruited; 92% were women ( N = 35/38). In patients who underwent RYGB, maximum plasma concentration ( C max ) was significantly reduced at 1 and 6 months after surgery compared with presurgery values ( p = 0.001). Regarding the AUC, the values are lower at 1 and 6 months after surgery than at baseline ( p < 0.001). The drug clearance was also increased in the first month after surgery. No differences were found between patients 6 months after surgery and controls. C max and AUC corrected by dose/body weight were significantly different between the baseline surgery subjects and controls. Discusion/Conclusions: Omeprazole bioavailability is reduced in patients with obesity at 1 and 6 months after RYGB. However, omeprazole PK parameters 6 months after RYGB are similar to control subjects, and thus no dose correction is required after RYGB for a given indication.