Acarbose

• Type 2 Diabetes Mellitus
• Postprandial Hyperglycemia
• Prediabetes (prevention)

Acarbose is an alpha-glucosidase inhibitor used in the management of type 2 diabetes mellitus. This medication works by slowing carbohydrate digestion and absorption, helping to control blood sugar spikes that occur after meals.

Mechanism of Action

Acarbose competitively inhibits pancreatic alpha-amylase and membrane-bound intestinal alpha-glucosidase enzymes in the brush border of the small intestine. These enzymes are responsible for breaking down complex carbohydrates and disaccharides into absorbable monosaccharides. By inhibiting these enzymes, acarbose delays carbohydrate digestion, resulting in a slower and more gradual rise in blood glucose after meals. This mechanism specifically targets postprandial hyperglycemia without directly affecting insulin secretion or sensitivity. The undigested carbohydrates pass to the large intestine where they are fermented by bacteria, which explains many of the medication's gastrointestinal side effects.

Available Formulations

Acarbose is available as oral tablets in 25 mg, 50 mg, and 100 mg strengths. The tablets should be taken with the first bite of each main meal to maximize effectiveness. Generic formulations are widely available.

Medical Uses

Acarbose is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. It is particularly useful in patients who have predominantly postprandial hyperglycemia or in combination with other antidiabetic medications. The drug may be used as monotherapy in patients who cannot tolerate or have contraindications to other antidiabetic drugs. Studies have also shown that acarbose can reduce the risk of progression from impaired glucose tolerance to type 2 diabetes and may provide cardiovascular benefits by reducing postprandial glucose excursions.

Dosing Guidelines

Treatment should be initiated with a low dose to minimize gastrointestinal side effects. The recommended starting dose is 25 mg three times daily with the first bite of each main meal. The dose may be increased at 4-8 week intervals based on blood glucose response and tolerability. The maximum recommended dose is 100 mg three times daily for patients over 60 kg and 50 mg three times daily for those under 60 kg. If no adequate response is observed with 100 mg three times daily, dosage increases are unlikely to provide additional benefit.

Important Safety Information

Acarbose is contraindicated in patients with diabetic ketoacidosis, inflammatory bowel disease, colonic ulceration, intestinal obstruction, or any condition that may deteriorate with increased intestinal gas formation. It should not be used in patients with chronic intestinal diseases associated with marked disorders of digestion or absorption. Rare cases of serious hepatotoxicity have been reported; liver function tests should be checked periodically, especially during the first year of treatment. If hypoglycemia occurs while taking acarbose with other antidiabetic medications, patients must use glucose (dextrose) rather than sucrose to treat it, as acarbose delays sucrose absorption.

Drug Interactions

Intestinal adsorbents (such as charcoal) and digestive enzyme preparations containing carbohydrate-splitting enzymes (amylase, pancreatin) may reduce the effect of acarbose. Thiazide diuretics, corticosteroids, thyroid hormones, and estrogens may cause hyperglycemia and reduce acarbose effectiveness. Acarbose may affect digoxin bioavailability, requiring monitoring when used together. The medication can enhance the hypoglycemic effect of sulfonylureas and insulin.

Special Populations

Acarbose is not recommended during pregnancy due to limited human data; insulin is preferred for managing diabetes during pregnancy. It is unknown whether acarbose is excreted in human breast milk, so use during breastfeeding should be based on risk-benefit assessment. Safety and effectiveness have not been established in pediatric patients. Elderly patients may be more sensitive to gastrointestinal effects. Acarbose is contraindicated in patients with significant renal impairment (serum creatinine greater than 2 mg/dL) as systemic accumulation may occur.