Origin and Chemical Structure
The drug acarbose, the primary representative of alpha-glucosidase inhibitors, has an interesting biological origin. Chemically, this substance is a complex carbohydrate—an oligosaccharide (specifically, a tetrasaccharide).
It is obtained not via classical chemical synthesis, but through biotechnological methods: the product is isolated during the targeted fermentation of specific microorganisms known in microbiology as Actinoplanes utahensis.
Sites of Action and Mechanism
The main task of alpha-glucosidase inhibitors is to prevent glucose absorption in the gastrointestinal tract. The mechanism of action is based on the reversible inhibition of key digestive enzymes. The drug has two primary sites of action:
- Inhibition of pancreatic $\alpha$-amylase: blocks the initial stage of digestion, namely the breakdown of complex dietary polysaccharides into disaccharides.
- Inhibition of intestinal membrane-bound $\alpha$-glucosidase: halts the next stage—the breakdown of disaccharides into final monosaccharides.
As a result of this dual enzymatic block, monosaccharide formation directly within the intestinal lumen is severely disrupted. The process of carbohydrate absorption is significantly slowed and reduced.
Pharmacological Effects and Therapeutic Role
The key clinical effect of acarbose is the reliable reduction of postprandial hyperglycemia—the sharp surge in blood sugar levels that regularly occurs after meals.
Importantly, the drug does not cause marked hypoglycemia. This is because alpha-glucosidase inhibitors do not stimulate endogenous insulin secretion by the pancreas; instead, they simply modulate the nutrient absorption process from food.
In clinical practice, the agent is most often prescribed as part of combination therapy alongside other oral hypoglycemic medications. For the drug to work correctly, the dosing regimen requires taking it strictly before meals.
Side Effects and Pathogenesis
The main pool of adverse events associated with acarbose intake relates to dyspeptic disorders. Patients most frequently complain of flatulence (occurring in 20–30% of patients) and abdominal pain. Diarrhea occurs significantly less often (in about 3% of cases).
The pathogenesis of these side effects directly stems from the drug's mechanism of action:
- Due to the enzyme blockade, unabsorbed carbohydrates cannot be taken up and remain in large quantities within the lumen of the small intestine.
- This carbohydrate mass becomes an excellent nutrient medium for the local intestinal microflora.
- An active process of fermentation of sugars by bacteria begins.
- During fermentation, an excessive amount of gas is released, leading to bloating, pain, and discomfort.
Contraindications
Considering its mechanism of action and direct effect on the gastrointestinal tract, alpha-glucosidase inhibitors have strict limitations for use.
They are strictly contraindicated in any conditions accompanied by impaired absorption function (e.g., clinically pronounced malabsorption syndrome). Additionally, the drug must not be prescribed to patients suffering from chronic inflammatory bowel disease (IBD), as excessive gas production, fermentation, and mucosal irritation can severely aggravate the underlying condition.