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Drug Absorption Post-Bariatric Surgery — FRCA Final MCQ

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ModeratePreoperative AssessmentDrug Absorption Post-Bariatric SurgeryFRCA Final

A 52-year-old man (ASA II) presents for elective cholecystectomy. He has a BMI of 31. Pre-operatively he mentions he had bariatric surgery (Roux-en-Y gastric bypass) 5 years ago. What is the most important pharmacological consideration following Roux-en-Y gastric bypass?

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Correct answer: B — Oral drug absorption may be unpredictable – particularly for modified-release formulations

Following Roux-en-Y gastric bypass, oral drug absorption is altered: (1) bypassed duodenum and proximal jejunum reduce the surface area for absorption, (2) altered gastric pH affects drug dissolution, (3) modified-release (MR/sustained-release) preparations may have unpredictable absorption and should be AVOIDED – use immediate-release formulations instead, (4) first-pass metabolism may be altered. Important examples: paracetamol absorption is faster (rapid gastric emptying), NSAID absorption may be increased (risk of anastomotic ulceration), and MR opioid preparations are unreliable. IV administration is preferred when drug levels are critical.

Reference: RCOA – 2023 – Bariatric anaesthesia; AAGBI – 2015 – Obesity perioperative management