Acarbose

Acarbose is an oral antidiabetic medication in the class of alpha-glucosidase inhibitors. It is used to improve glycemic control in adults with type 2 diabetes, particularly for reducing postprandial glucose excursions. It is typically added to diet and exercise and may be used in combination with other antidiabetic agents such as metformin or a sulfonylurea. Brand names include Precose and Glucobay, with generic forms also available.

Mechanism of action: Acarbose acts locally in the small intestine by reversibly inhibiting brush-border alpha-glucosidase enzymes. This slows the digestion of complex carbohydrates into absorbable monosaccharides, producing a slower and smaller rise in postprandial blood glucose. It has minimal effect on fasting glucose and insulin levels.

Pharmacokinetics: Acarbose is poorly absorbed from the gastrointestinal tract, and systemic exposure is low. Most of its activity remains in the intestinal lumen. The drug is metabolized and excreted as inactive metabolites in the gut, with little systemic effect.

Administration and dosing: The medication is taken with the first bite of each main meal. Typical starting dose is 25 mg per meal, titrated to 50 mg, and then to 100 mg per meal as tolerated, with a maximum of 100 mg per meal (300 mg/day for three meals). Dosing may be adjusted for renal impairment and tolerability.

Adverse effects and safety: The most common adverse effects are gastrointestinal, including flatulence, abdominal bloating, and diarrhea, which are dose-related and often transient. Hypoglycemia can occur when used with insulin or a sulfonylurea; hypoglycemia should be treated with glucose rather than sucrose, since acarbose delays carbohydrate digestion. Rare hepatic dysfunction has been reported with long-term use. Contraindications include inflammatory bowel disease, intestinal obstruction, and malabsorption syndromes.