A 55-year-old woman with type 2 diabetes is started on acarbose with meals. After two weeks she complains of excessive flatulence and bloating. The mechanism of these gastrointestinal side effects is:

• A Osmotic fluid shift into the colonic lumen from undigested disaccharides
• B Altered gut motility from inhibition of motilin receptors
• C Direct stimulation of serotonin receptors in the enteric nervous system
• D Bacterial fermentation of unabsorbed carbohydrates in the colon producing gas ✓

Explanation

Acarbose inhibits alpha-glucosidase in the small intestinal brush border, delaying carbohydrate digestion and absorption. Unabsorbed carbohydrates reach the colon where bacterial fermentation produces hydrogen, carbon dioxide, and methane, causing flatulence and bloating. The osmotic diarrhea seen with some agents is less prominent here because gas production dominates the symptom profile.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.