Systematic review of drug bioavailability following gastrointestinal surgery

Inter- and intraindividual pharmacokinetics variability in humans affects the way in which drugs act on the body. Gastrointestinal surgery has an impact on this variability and significantly alters the kinetics of drugs in post-surgical patients. The way in which pharmacokinetic profiles are modified depends on the type of operative procedure performed. The extent to which the absorption of different groups of drugs is affected varies according to the site and length of intestinal resections.

A literature search was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Three databases were searched: MEDLINE, Embase, and the Cochrane Library. For each drug, potential changes in absorption were described, including recommendations extracted from the results of the studies and collected according to authors' criteria as practical conclusions, and grades of recommendation were determined by levels of evidence using the Oxford Centre for Evidence-Based Medicine scale.

Sixty-eight articles were collected during the selection process after the bibliographic search. The main outcomes for 60 drugs from the various studies were classified according to each type of surgery.

Modifications in the digestive tract secondary to gastrointestinal surgery may compromise the bioavailability of drugs. Decreased absorption surface, gastric emptying speed, and gastric pH alteration are factors to be taken into account in the management of pharmacological treatment after surgery. Evidence supported by data in clinical practice is scarce, but after studying the pharmacokinetic profile of some molecules, it is possible to offer recommendations for its adaptation to the patient's clinical situation.