acarbose
Brand: Precose
Prototype Drug
Drug Class: alpha-glucosidase inhibitor
Drug Family: antidiabetic
Subclass: intestinal alpha-glucosidase inhibitor
Organ Systems: endocrine
Mechanism of Action
Competitively inhibits intestinal alpha-glucosidases (maltase, sucrase, isomaltase, glucoamylase) at the brush border of the small intestine, slowing the breakdown of complex carbohydrates and sucrose to glucose. This delays and reduces postprandial glucose absorption.
alpha-glucosidase enzymes (intestinal brush border)
Indications
- type 2 diabetes mellitus (reduces postprandial hyperglycemia)
Contraindications
- inflammatory bowel disease
- colonic ulceration
- intestinal obstruction
- cirrhosis
- severe renal impairment (CrCl <25 mL/min)
Adverse Effects
Common
- flatulence (most common — up to 77%)
- diarrhea
- abdominal cramping
Serious
- hepatotoxicity (rare, with high doses)
- ileus (rare)
Pharmacokinetics (ADME)
| Absorption | oral; minimally absorbed (<2%); acts locally in GI tract |
| Distribution | local GI tract |
| Metabolism | metabolized by intestinal bacteria; minor hepatic metabolism of absorbed fraction |
| Excretion | fecal (primary); minor renal excretion of absorbed fraction |
| Half-life | 2 hours |
| Onset | rapid (during meal) |
| Peak | during meal |
| Duration | postprandial period |
| Protein Binding | minimal |
| Vd | minimal |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| digestive enzymes (amylase, pancreatin) | antagonize action of acarbose | moderate |
| insulin or sulfonylureas | acarbose combined with secretagogues can increase hypoglycemia risk; treat hypoglycemia with GLUCOSE (not sucrose) | moderate |
Nursing Considerations
- Administer with the FIRST BITE of each main meal (3 times daily); taking before or after a meal reduces efficacy.
- If hypoglycemia occurs while on acarbose (in combination with insulin/SU), treat ONLY with pure glucose (dextrose or glucose tabs) NOT sucrose (sucrose cannot be digested when acarbose is active).
- Monitor LFTs at 3-month intervals for first year; rare hepatotoxicity at high doses.
- GI side effects are dose-related; start at low dose (25 mg) and titrate slowly; side effects typically decrease over time as gut flora adapts.
Clinical Pearls
- The critical clinical pearl: hypoglycemia occurring in a patient on acarbose MUST be treated with glucose tablets or IV dextrose — table sugar (sucrose) cannot be properly digested because sucrase is inhibited.
- Acarbose has a favorable safety profile (minimal systemic absorption) but is limited in clinical use by its GI side effects; it is more commonly used in Asia than in the United States.
Safety Profile
Pregnancy insufficient-data
Lactation avoid
Renal Adjustment Required
Hepatic Adjustment Required
TDM Not required
Concordance Terms
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