Proton Pump Inhibitors (PPIs)
According to many local protocols, PPIs are frequently prescribed after bariatric surgery for the prevention of ulceration, even though the duration of prophylactic PPI use seems to vary. In an internet-based survey among members of the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) on the management of anastomotic ulcers after RYGB surgery, 88% of the 189 participants reported the prescription of prophylactic medication of which 91% preferred proton pump inhibitors 111. The prophylactic medication was prescribed for a period of one month in 25% of the cases, for a period of three months in 37% of the cases, for a period of six months in 28% of the cases, for more than six months in 4% of the cases and lifelong for 5% of the cases with a median of three months111. Even though the majority (~75%) of ulceration appears to occur in the first year after surgery with the steepest increase in the first six months (~60%)78, the available literature regarding this subject is not conclusive on the duration of prophylaxis in this population78–80,82,84,112.
Since the prescription and usage of PPIs is widespread, information on the absorption and dose is of relevance. Mitrov-winkelmolen et al. studied the pharmacokinetics of omeprazole in 34 patients with morbid obesity the months – two weeks before and more than six weeks after RYGB. Tmax after surgery was 0.9 h compared to 2.1h before surgery, Cmax was higher (958.6±300.8 μg/l vs. (731.1±339.0 μg/l) and AUC0–12 was lower (2834.1±1560.4 vs. 3737.4±21932 μg h/l) after surgery 27. Another study in 18 RYGB subjects one year after surgery also showed a reduced Tmax (0.75h vs. 4h) but no alterations in other PK parameters compared to matched controls 113. This discrepancy might be explained by differences in study design (matched vs. repeated measure design) and/or large inter-individual variability in omeprazole PK. Also, the timing of the study in relation to surgery, can be relevant.
Another factor that might contribute to therapy failure of PPIs is the dissolution of the capsule, which was investigated by Schulman et al., reporting shorter healing time when the capsule was opened (as described under Disintegration of the oral drug formulation) 21. Therefore, in case an inadequate response is observed, opening the PPI capsule can be advised provided that PPIs do not get in contact with acid to prevent degradation 114. Therefore, PPI capsules can only be opened when this is allowed according to the SmPC.