Usage
- Acarbose is prescribed for type 2 diabetes mellitus. It is used as an adjunct to diet and exercise to improve glycemic control in patients whose diabetes is not adequately managed by diet and exercise alone. It may be used as monotherapy or in combination with other antidiabetic medications such as sulfonylureas, metformin, or insulin.
- Pharmacological Classification: Alpha-glucosidase inhibitor, antidiabetic agent.
- Mechanism of Action: Acarbose competitively and reversibly inhibits alpha-glucosidase enzymes in the brush border of the small intestine. These enzymes are responsible for breaking down complex carbohydrates (starch and sucrose) into monosaccharides (glucose and fructose) which can then be absorbed. By inhibiting these enzymes, acarbose slows the rate of carbohydrate digestion and absorption, thus reducing the postprandial rise in blood glucose.
Alternate Names
- International Nonproprietary Name (INN): Acarbose
- Brand Names: Precose, Glucobay, Prandase, Ascar, Glicobase.
How It Works
- Pharmacodynamics: Acarbose reduces postprandial hyperglycemia by delaying the absorption of glucose. This leads to a lower peak blood glucose level and a flatter glucose curve after meals. It does not stimulate insulin secretion and therefore does not cause hypoglycemia when used as monotherapy.
- Pharmacokinetics:
- Absorption: Minimally absorbed (1-2%). The absorbed fraction is metabolized by intestinal bacteria. The majority of the drug is excreted in feces.
- Metabolism: Metabolized by intestinal flora.
- Elimination: Primarily fecal excretion; small amounts are excreted in urine as metabolites.
- Mode of Action: Acarbose binds to the alpha-glucosidase enzymes at the brush border of the small intestines, preventing the hydrolysis of complex carbohydrates into absorbable monosaccharides like glucose.
- Receptor Binding/Enzyme Inhibition/Neurotransmitter Modulation: Acarbose acts through competitive and reversible inhibition of alpha-glucosidase, primarily the sucrase and maltase enzymes. It does not bind to receptors or modulate neurotransmitters.
- Elimination Pathways: Primarily through fecal excretion of the unabsorbed drug; a small amount is metabolized by gut bacteria and excreted in urine.
Dosage
Standard Dosage
Adults:
- Initial: 25 mg three times daily taken orally with the first bite of each main meal.
- Maintenance: May be increased to 50 mg three times daily, and then, if needed and tolerated, up to a maximum of 100 mg three times daily. Dosage should be adjusted at 4-8 week intervals based on postprandial glucose or HbA1c levels and tolerance.
- Maximum dose: 100 mg TID for patients >60 kg. 50 mg TID for patients ≤60 kg.
Children:
- Not recommended for use in children under 18 years of age, as safety and efficacy have not been established.
Special Cases:
- Elderly Patients: No dosage adjustment is generally needed, but closer monitoring for adverse effects is advised.
- Patients with Renal Impairment: Use with caution in patients with creatinine clearance <25 mL/min/1.73 m². Dose adjustments may be required based on renal function.
- Patients with Hepatic Dysfunction: No dosage adjustment necessary for mild to moderate hepatic impairment. Contraindicated in severe hepatic impairment.
- Patients with Comorbid Conditions: Use with caution in patients with intestinal conditions such as inflammatory bowel disease, colonic ulceration, or intestinal obstruction. Closely monitor patients with these conditions.
Clinical Use Cases
- Acarbose is not indicated for use in specific clinical settings like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations. It’s primarily for chronic management of type 2 diabetes.
Dosage Adjustments
- Dose titration based on 1-hour postprandial glucose or HbA1c. Start with a lower dose and titrate gradually at 4- to 8-week intervals based on glycemic control and gastrointestinal tolerance.
Side Effects
Common Side Effects
- Flatulence
- Abdominal pain
- Diarrhea
- Bloating
Rare but Serious Side Effects
- Hepatic dysfunction (jaundice, elevated liver enzymes)
- Intestinal obstruction
- Pneumatosis cystoides intestinalis (gas cysts in the intestinal wall)
- Severe allergic reactions (anaphylaxis)
Long-Term Effects
- Chronic gastrointestinal issues may develop with prolonged use. Regular monitoring of liver function tests is advisable.
Adverse Drug Reactions (ADR)
- Serious allergic reactions: angioedema, anaphylaxis, erythema, urticaria.
- Fulminant hepatitis (rare)
Contraindications
- Hypersensitivity to acarbose
- Inflammatory bowel disease (Crohn’s disease, ulcerative colitis)
- Colonic ulceration
- Intestinal obstruction
- Cirrhosis
- Diabetic ketoacidosis
- Pregnancy
- Breastfeeding
- Creatinine clearance <25 mL/min/1.73m² (severe renal impairment)
Drug Interactions
- Digestive enzymes: Reduced acarbose efficacy.
- Insulin or sulfonylureas: Increased risk of hypoglycemia.
- Intestinal adsorbents (e.g., charcoal): Decreased acarbose absorption.
- Drugs that increase blood glucose (e.g., corticosteroids, thiazide diuretics, estrogens, isoniazid, phenytoin, nicotinic acid): May decrease acarbose efficacy.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: Category B (animal studies have not demonstrated fetal risk, but there are no adequate and well-controlled studies in pregnant women). Acarbose is generally not recommended during pregnancy.
- Breastfeeding: Acarbose is excreted in rat milk. It is not known whether it is excreted in human milk. Due to the potential for adverse effects in the nursing infant, acarbose is not recommended during breastfeeding.
Drug Profile Summary
- Mechanism of Action: Inhibits alpha-glucosidase, delaying carbohydrate absorption and reducing postprandial glucose peaks.
- Side Effects: Flatulence, abdominal pain, diarrhea, bloating. Rarely: hepatic dysfunction, intestinal obstruction.
- Contraindications: IBD, colonic ulceration, intestinal obstruction, cirrhosis, DKA, pregnancy, breastfeeding. Severe renal impairment.
- Drug Interactions: Digestive enzymes, insulin/sulfonylureas, intestinal adsorbents, drugs that increase blood glucose.
- Pregnancy & Breastfeeding: Not recommended.
- Dosage: Initial: 25 mg TID, max: 100 mg TID (>60 kg), 50 mg TID (≤60 kg) with meals.
- Monitoring Parameters: HbA1c, fasting and postprandial blood glucose, liver function tests.
Popular Combinations
Precautions
- General Precautions: Monitor liver function tests periodically. Counsel patients on diet and the importance of adherence.
- Specific Populations: Not recommended for pregnant or breastfeeding women. Use cautiously in patients with renal impairment and the elderly.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Acarbose?
A: Initial: 25 mg orally three times daily with meals. Can increase to 50 mg TID, and then to a maximum of 100 mg TID (for patients >60 kg) or 50 mg TID (for patients ≤ 60 kg), adjusting every 4-8 weeks based on glucose control and tolerability.
Q2: What is the mechanism of action of Acarbose?
A: Acarbose inhibits alpha-glucosidase enzymes in the small intestine, delaying the breakdown and absorption of carbohydrates, which reduces postprandial hyperglycemia.
Q3: What are the common side effects of Acarbose?
A: The most common side effects are gastrointestinal: flatulence, abdominal pain, diarrhea, and bloating.
Q4: Can Acarbose cause hypoglycemia?
A: Acarbose itself does not usually cause hypoglycemia when used as monotherapy. However, when combined with other antidiabetic agents like insulin or sulfonylureas, the risk of hypoglycemia increases.
Q5: Is Acarbose safe in pregnancy?
A: Acarbose is generally not recommended for use during pregnancy.
Q6: What are the contraindications for Acarbose?
A: Contraindications include: IBD, colonic ulceration, intestinal obstruction, cirrhosis, diabetic ketoacidosis, pregnancy, breastfeeding, and severe renal impairment.
Q7: What should I advise my patient about taking Acarbose?
A: Take acarbose with the first bite of each main meal. Adhere to the prescribed diet and exercise regimen. Report any severe gastrointestinal side effects or signs of liver problems. Do not use sucrose to treat hypoglycemia if it occurs; use glucose instead.
Q8: How should hypoglycemia be managed in patients taking Acarbose?
A: Because acarbose slows sucrose digestion, use glucose (dextrose) tablets, gel, or other readily absorbable forms of glucose, not sucrose, to treat hypoglycemia.
Q9: Does Acarbose interact with other medications?
A: Yes, acarbose can interact with several medications, including digestive enzymes, insulin/sulfonylureas, intestinal adsorbents, and drugs that increase blood glucose. Be sure to review your patient’s medication list for potential interactions.
