In the case of the majority of studied drugs , an increased absorption rate was observed early after RYGBP .
The effect on systemic exposure allows for a low degree of extrapolation , including between drugs subjected to the same major metabolic and transporter pathways .
Anatomical changes in the gastrointestinal tract and subsequent weight loss may influence drug disposition and thus drug dosing following bariatric surgery .
This review systematic ally examines the effects of bariatric surgery on drug pharmacokinetics , focusing especially on the mechanisms involved in restricting oral bioavailability .
The Effect of Roux-en-Y Gastric Bypass Surgery in Morbidly Obese Patients on Pharmacokinetics of (Acetyl)Salicylic Acid and Omeprazole: the ERY-PAO Study
Background Data on the absorption of orally administered drugs following  Roux-en-Y gastric bypass ( RYGB ) surgery in obese patients are limited and inconclusive . As it is difficult to predict changes in absorption , studies on frequently used drugs in this population are necessary . Acetylsalicylic acid ( ASA ) and omeprazole are two commonly prescribed drugs in obese patients . Methods In this repeated measures study , omeprazole and salicylic acid ( SA ) serum concentrations were measured before and after RYGB in 34 morbidly obese subjects .  Time to maximum concentration ( Tmax ) , lag time ( Tlag ) , maximum concentration ( Cmax ) , and area under the serum concentration versus time curve ( AUC ) were calculated for both drugs to determine possible differences in drug absorption after the procedure . Results For SA , Tmax significantly decreased after RYGB , while both Cmax and AUC0–24 significantly increased . For omeprazole , both Tmax and Tlag significantly decreased after RYGB , while Cmax significantly increased . Mean AUC0–12 significantly decreased post-surgery . The difference in AUC0–12 before and after surgery varied between subjects . Conclusions Our study shows a faster absorption of both ASA and omeprazole after RYGB . The exposure to ASA is higher post-surgery , but the st and ard dose of 80 mg does not need to be modified , considering its range in effective dose . The exposure to omeprazole is , on average , decreased after surgery . Clinicians should be aware to increase the dose of omeprazole if symptoms suggest inadequate response
In the case of the majority of studied drugs , an increased absorption rate was observed early after RYGBP .
The effect on systemic exposure allows for a low degree of extrapolation , including between drugs subjected to the same major metabolic and transporter pathways .
Anatomical changes in the gastrointestinal tract and subsequent weight loss may influence drug disposition and thus drug dosing following bariatric surgery .
This review systematic ally examines the effects of bariatric surgery on drug pharmacokinetics , focusing especially on the mechanisms involved in restricting oral bioavailability .