Anti-Obesity Drug Discovery and Development

Volume: 1

Medication Absorption Post-Bariatric Surgery with Emphasis on Management of Vitamin Deficiencies

Author(s): Susan Jacob, Nhu Nguyen, Christian S. Jackson and Stewart Rendon

Pp: 265-282 (18)

DOI: 10.2174/978160805163211101010265

* (Excluding Mailing and Handling)


The increased prevalence of obesity worldwide has led to a rise in bariatric surgeries performed each year. Bariatric surgery is currently one of the most effective interventions for weight loss. The most common procedures include gastric bypass, adjustable gastric band, jejunoileal bypass, vertical banded gastroplasty, and biliopancreatic diversion with duodenal switch. Bariatric surgery can improve various medical conditions including but not limited to diabetes, hypertension, dyslipidemia, reflux, and obstructive sleep apnea. Patients with type 2 diabetes develop increased insulin sensitivity and improvements in glucose metabolism within days after surgery. As weight loss occurs, blood pressure and cholesterol levels may improve post operatively, allowing discontinuation of medications. Due to the possible achlorhydric nature of the gastrointestinal tract, post surgery patients often do not require acid suppressing agents for reflux. Medication absorption is highly affected by post gastric bypass surgery, specifically drug solubility and surface area for absorption. These changes warrant manipulation in drug route or dose to ensure adequate delivery. As weight loss occurs, medication adjustments are essential to provide optimal bioavailability for various health related conditions. Consideration should be made for certain medications that depend on absorption site and pH of the gastrointestinal tract for solubility and proper absorption. Non-steroidal anti-inflammatory drugs, aspirin, and bisphosphonates, should be discontinued as these can cause an increased risk of stomach ulcerations if continued post surgery. Long acting and enteric coated formulations will not be absorbed as they require an extended period of time in the intestines for drug dissolution and metabolism. Patients undergoing bariatric surgery have alterations in the digestive anatomy resulting in micronutrient and mineral deficiencies requiring immediate postoperative vitamin supplementations. Nutrient deficiencies include calcium, fat soluble vitamins (A, D, E, K), thiamine, iron, folic acid, and cyanocobalamin. Calcium and vitamin D deficiencies may cause secondary hyperparathyroidism and bone softening diseases. Cyanocobalamin deficiency may lead to irreversible peripheral neuropathy. Wernicke’s encephalopathy is common in patients with thiamine deficiency. Anemia may develop in patients with iron deficiency. Due to rapid weight loss and physiological changes, patient monitoring for therapeutic effects is crucial. Recent developments in anti-obesity therapies such as bariatric surgery have revealed improvements or complete remission of multiple chronic diseases. Manipulation of the gastrointestinal tract post bariatric surgery requires medication adjustments and vitamin supplementation for optimal patient care.

Keywords: Bariatric surgery, vitamin deficiency, medication adjustments.

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