acarbose
Precose

Available forms
Available by prescription only
Tablets: 25 mg, 50 mg, 100 mg

Indications and dosages
 Dietary adjunct to lower blood glucose levels in patients with type 2 diabetes mellitus whose hyperglycemia can’t be managed by diet alone or by diet and a sulfonylurea, or adjunct to insulin or metformin; adjunct to insulin or metformin therapy in patients with type 2 diabetes mellitus whose hyperglycemia can’t be managed by diet, exercise, and insulin or metformin alone. Adults: Initially, 25 mg P.O. t.i.d. with the first bite of each main meal. Subsequent dosage adjustment made at 4- to 8-week intervals based on 1-hour postprandial glucose levels and tolerance. Maintenance dosage is 50 to 100 mg P.O. t.i.d. depending on patient’s weight. Maximum dose for patients weighing 60 kg (132 lb) or less is 50 mg P.O. t.i.d.; for patients weighing over 60 kg, maximum dose is 100 mg P.O. t.i.d.

Pharmacodynamics
Antidiabetic action: The ability of acarbose to lower blood glucose results from a competitive, reversible inhibition of pancreatic alpha-amylase and membrane-bound intestinal alpha-glucoside hydrolase enzymes. In diabetic patients, this enzyme inhibition results in delayed glucose absorption and a lowering of postprandial hyperglycemia. The drug doesn’t enhance insulin secretion.

Pharmacokinetics
Absorption: Minimally absorbed.
Distribution: Acts locally in the GI tract.
Metabolism: Metabolized exclusively within the GI tract, principally by intestinal bacteria with some metabolized action caused by digestive enzymes.
Excretion: Within 96 hours, 51% of dose is excreted in feces as unabsorbed drug. The fraction of drug absorbed is almost completely excreted by the kidneys. Plasma elimination half-life of acarbose is about 2 hours. Drug accumulation doesn’t occur with t.i.d. oral dosing.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug and in those with diabetic ketoacidosis, cirrhosis, inflammatory bowel disease, colonic ulceration, partial intestinal obstruction, or predisposition to intestinal obstruction. Also contraindicated in patients with chronic intestinal diseases that cause marked disorders of digestion or absorption and in those with conditions that may deteriorate because of increased gas formation in the intestine. Avoid using drug in patients with serum creatinine levels above 2 mg/dl and in breast-feeding or pregnant women.
  Use cautiously in patients with mild to moderate renal impairment.

Interactions
Drug-drug. Calcium channel blockers, corticosteroids, estrogens, hormonal contraceptives, isoniazid, nicotinic acid, phenothiazines, phenytoin, sympathomimetics, thiazides and other diuretics, and thyroid products: May cause hyperglycemia or hypoglycemia when withdrawn. Monitor patient’s blood glucose level.
Digoxin: Decreases serum digoxin level and therapeutic effects. Monitor digoxin level.
Insulin, sulfonylureas: May increase hypoglycemic potential of these agents. Monitor blood glucose level closely.
Intestinal adsorbents (activated charcoal), digestive enzyme preparations containing carbohydrate-splitting enzymes (amylase, pancreatin): May reduce effect of acarbose. Don’t administer together.

Adverse reactions
GI: abdominal pain, diarrhea, flatulence.
Hepatic: liver impairment.
Metabolic: hypocalcemia, vitamin B deficiency.

Effects on lab test results
• May increase ALT and AST levels. May decrease calcium and vitamin B₆ levels.

Overdose and treatment
Unlike sulfonylureas or insulin, acarbose overdose doesn’t result in hypoglycemia. An overdose may result in transient increases in flatulence, diarrhea, and abdominal discomfort, which quickly subside.

Special considerations
• Acarbose isn’t effective as sole therapy in patients with diabetes mellitus complicated by acidosis, ketosis, or coma; management of these conditions requires the use of insulin.
• Acarbose alone doesn’t cause hypoglycemia. However, when given with a sulfonylurea or insulin, it may increase the hypoglycemic potential of the sulfonylurea. Closely monitor patient receiving both drugs. If hypoglycemia occurs, treat with oral glucose (dextrose), whose absorption isn’t inhibited by acarbose, rather than sucrose (cane sugar). Severe hypoglycemia may require I.V. glucose infusion or glucagon administration. Dosage adjustment in acarbose and sulfonylurea may be required to prevent further episodes of hypoglycemia.
• During periods of increased stress, such as infection, fever, surgery, or trauma, patient may require insulin therapy. Monitor patient closely for hyperglycemia in these situations.
• Monitor patient’s 1-hour postprandial plasma glucose levels to determine effectiveness of acarbose and to identify appropriate dose. Thereafter, measure glycosylated hemoglobin every 3 months. Treatment goals include decreasing both postprandial plasma glucose and glycosylated hemoglobin levels to normal or near normal by using the lowest effective dose of acarbose either as monotherapy or with sulfonylureas.
• Monitor serum transaminase levels every 3 months during first year of therapy and then periodically thereafter in patients receiving doses exceeding 50 mg three times daily. Abnormalities may require dosage adjustment or withdrawal of drug.
Breast-feeding patients
• It isn’t known if drug appears in breast milk. Acarbose shouldn’t be given to breast-feeding women.
Pediatric patients
• Safety and efficacy in patients younger than age 18 haven’t been established.

Patient education
• Tell patient to take drug with the first bite of each of three main meals daily.
• Make sure patient understands that therapy relieves symptoms but doesn’t cure disease.
• Stress the importance of adhering to specific diet, weight reduction, exercise, and personal hygiene programs. Explain how and when to monitor blood glucose level, and teach recognition of and intervention for hyperglycemia.
• Teach patient to recognize and intervene for hypoglycemia if a sulfonylurea drug is also taken. Tell patient to treat symptoms of hypoglycemia with a form of dextrose instead of products containing table sugar.
• Advise patient to wear or carry medical identification regarding diabetic status.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use