Medication Management After Gastric Bypass Surgery

High-Risk Medications

• The American Society of Anesthesiologists recommends that insulin and sulfonylureas must be drastically reduced or discontinued immediately postoperatively due to the rapid reduction in insulin requirement starting immediately after gastric bypass surgery 1
• Gastric bypass causes a unique neuro-humeral response that creates profound changes in glucose metabolism within days of surgery, according to the American Diabetes Association 1
• The American College of Surgeons advises cautious postoperative reintroduction of diabetic medication and frequent blood sugar monitoring to prevent life-threatening hypoglycemia 1

Medications Requiring Dose Adjustment

• The American Society of Anesthesiologists recommends that most anesthetic agents should be dosed to lean body weight or adjusted body weight, NOT total body weight, to prevent relative overdose 1, 2
• The American Heart Association notes that patients with obesity hypoventilation syndrome are particularly susceptible to respiratory depression from anaesthetic agents and opioids, which may precipitate respiratory arrest in the early postoperative period 1, 2

Medications with Altered Absorption

• The National Institute of Diabetes and Digestive and Kidney Diseases states that extended-release and enteric-coated medications may have unpredictable absorption after gastric bypass due to altered gastrointestinal anatomy and rapid transit through the shortened gastric pouch 3

Cardiovascular Medications

• The American Heart Association warns that ondansetron and other QT-prolonging drugs carry increased risk given the increased incidence of prolonged QT interval with increasing BMI 1
• The American College of Cardiology recommends that baseline ECG should be obtained preoperatively in patients with at least one risk factor for coronary heart disease 4

Pharmacotherapy Considerations

• The American Gastroenterological Association advises that sympathomimetic agents such as phentermine and phentermine/topiramate ER should not be prescribed in patients with cardiovascular disease 5
• The Endocrine Society recommends that lorcaserin and orlistat are safer alternatives for patients requiring continued weight management pharmacotherapy 5
• The American Diabetes Association suggests that GLP-1 analogues may be appropriate for patients with type 2 diabetes requiring continued glycemic management 5