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.