One-anastomosis gastric bypass and oral semisynthetic penicillins bioavailability: Clinical pharmacology analysis

Introduction. One-anastomosis gastric bypass (OAGB) is a bypass bariatric procedure that combines restrictive and malabsorptive components and is associated with anatomical changes in the upper gastrointestinal tract. After this operation, the food stream bypasses the duodenum and the proximal jejunum, which may affect the absorption of oral medications, including semisynthetic penicillins.

Objective. To assess the potential effect of OAGB on the bioavailability of oral semisynthetic penicillins and to define clinical pharmacology approaches to their use in patients after this type of bypass bariatric procedure.

Materials and methods. A review and clinical pharmacology analysis of published data were performed. The search included studies on anatomical and physiological changes after bariatric surgery, mechanisms of intestinal absorption of amoxicillin, ampicillin, amoxicillin with clavulanic acid, and penicillinase-resistant isoxazolyl penicillins, primarily oxacillin, as well as studies on the pharmacokinetics of oral antibiotics after bypass bariatric procedures. The literature search was conducted in international and Russian scientific databases, including PubMed, Cochrane Library, Google Scholar, Crossref, eLibrary.ru, and CyberLeninka, as well as on the websites of scientific journals and publishers. Publications with verifiable digital object identifiers and Russian sources on bariatric surgery were additionally analyzed.

Results and discussion. No direct clinical pharmacokinetic studies of oral semisynthetic penicillins specifically after one-anastomosis gastric bypass were identified in the available literature. Most evidence comes from studies after Roux-en-Y gastric bypass and suggests that systemic exposure to amoxicillin may be unpredictable, especially when solid dosage forms are used. Potentially relevant factors include exclusion of the proximal small intestine, changes in gastric pouch acidity, accelerated intestinal transit, dosage form, hypoalbuminemia, and signs of malabsorption.

Conclusion. Oral penicillins after OAGB should not be considered inherently ineffective. However, their use requires assessment of infection severity, dosage form, preserved oral intake, and early clinical response. In severe infection, systemic inflammatory manifestations, or signs of unreliable oral exposure, parenteral administration is preferable.

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