Also Known As: Acarbose, Precose, Prandase
Acarbose is an anti-diabetic drug used to treat type 2 diabetes mellitus and, in some countries, prediabetes. It is a generic sold in Europe and China as Glucobay (Bayer AG), in North America as Precose (Bayer Pharmaceuticals), and in Canada as Prandase (Bayer AG). It is cheap and popular in China, but not in the U.S., because it is not potent enough to justify the side effects of diarrhea and flatulation. It is a starch blocker, and inhibits alpha glucosidase, an intestinal enzyme that releases glucose from larger carbohydrates. It is composed of an acarviosin moiety with a maltose at the reducing terminus.
Acarbose inhibits enzymes (glycoside hydrolases) needed to digest carbohydrates, specifically, alpha-glucosidase enzymes in the brush border of the small intestines and pancreatic alpha-amylase. Pancreatic alpha-amylase hydrolyzes complex starches to oligosaccharides in the lumen of the small intestine, whereas the membrane-bound intestinal alpha-glucosidases hydrolyze oligosaccharides, trisaccharides, and disaccharides to glucose and other monosaccharides in the small intestine. Inhibition of these enzyme systems reduces the rate of digestion of complex carbohydrates. Less glucose is absorbed because the carbohydrates are not broken down into glucose molecules. In diabetic patients, the short-term effect of these drugs therapies is to decrease current blood glucose levels; the long-term effect is a reduction in HbA1c level. This reduction averages an absolute decrease of 0.7%, which is a decrease of about 10% in typical HbA1c values in diabetes studies.
Since acarbose prevents the digestion of complex carbohydrates, the drug should be taken at the start of main meals (taken with first bite of meal). Moreover, the amount of complex carbohydrates in the meal will determine the effectiveness of acarbose in decreasing postprandial hyperglycemia. Adults may take doses of 25 mg 3 times daily, increasing to 100 mg 3 times a day.