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 gastric bypass on the pharmacokinetics of serotonin reuptake inhibitors.
OBJECTIVE Morbidly obese patients frequently present with mood and anxiety disorders , which are often treated with serotonin reuptake inhibitors ( SRIs ) . Having observed that patients treated with SRIs frequently relapse after Roux-en-Y gastric bypass surgery , the authors sought to assess whether SRI bioavailability is reduced postoperatively . METHOD Twelve gastric bypass c and i date s treated with an SRI for primary mood or anxiety disorders were studied prospect ively . Timed blood sample s for  SRI plasma levels were drawn for pharmacokinetic studies before surgery and 1 , 6 , and 12 months afterward . Maximum concentration , time to maximum concentration , and area under the concentration/time curve ( AUC ) were determined . RESULTS In eight of the 12 patients , AUC values 1 month after surgery dropped to an average of 54 % ( SD=18 ) of preoperative levels ( range=36%-80 % ) ; in six of these patients , AUC values returned to baseline levels ( or greater ) by 6 months . Four patients had an exacerbation of depressive symptoms , which resolved by 12 months in three of them . Three of the four patients had a reduced AUC level at 1 month and either gained weight or failed to lose weight between 6 and 12 months . Normalization of the AUC was associated with improvement in symptom scores . CONCLUSIONS Patients taking SRIs in this study were at risk for reduced drug bioavailability 1 month after Roux-en-Y gastric bypass . The authors recommend close psychiatric monitoring after surgery
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 .