Acarbose, an Intestinal Alpha-Glucosidase Inhibitor, decreases postprandial hyperglycemia by inhibiting the digestion and absorption of carbohydrates. It achieves this by inhibiting the enzymes responsible for the digestion of starches and other carbohydrates in the brush border of the small intestine.The peak action of acarbose occurs within 1 hour of ingestion. The drug is metabolized by intestinal bacteria and digestive enzymes. Because the half-life for acarbose is only about 2 hours, the drug should be taken three times a day.

A physician will begin acarbose therapy at 25 mg three times a day. She will adjust dosages every 4 to 8 weeks based on 1-hour postprandial blood glucose levels and on tolerance until an effective dose is achieved. The maximum recommended dosage is 50 mg three times a day for patients who weigh 60 kg or less. For those who weigh more than 60 kg, the maximum dosage is 100 mg three times a day.

Indications and Contraindications

Acarbose is used with stable Type 2 patients as an adjunct to diet and exercise to reduce blood glucose levels. This drug benefits patients who can’t achieve near-normal blood glucose levels with sulfonylureas or metformin.

Because acarbose increases gas formation in the intestine, it’s contraindicated for anyone with inflammatory bowel disease, ulcerations of the colon, or intestinal obstruction. The drug is also contraindicated for patients with chronic intestinal diseases that alter digestion or absorption. Acarbose is contraindicated during pregnancy or breast-feeding. Patients with kidney dysfunction, DKA, or a hypersensitivity to the drug also shouldn’t take it.

Adverse Effects and Interactions

The most common reactions to acarbose are GI signs and symptoms. Patients may complain of abdominal pain, diarrhea, and flatulence caused by undigested carbohydrates in the intestines. These signs and symptoms tend to subside with time. At doses of 100 mg, acarbose may cause an asymptomatic, reversible increase in serum transaminase levels, especially in women.

The action of acarbose decreases with the concurrent use of charcoal, an intestinal adsorbent, and digestive enzyme preparations that contain carbohydrate-splitting enzymes, such as amylase and pancreatin. Hyperglycemia may result if a patient takes acarbose with thiazide and other diuretic drugs, beta-blockers, corticosteroids, phenothiazines, thyroid preparations, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blockers, or isoniazid. Acarbose can be taken with a sulfonylurea or insulin, but these combinations may cause hypoglycemia. However, acarbose can help to prevent weight gain associated with sulfonylurea therapy.

Advise your patients to take acarbose with meals. Because the goal is to prevent the absorption of intestinal glucose, they should take the drug along with the first bite of food. No food interactions occur.