Miglitol delays glucose absorption
Miglitol delays glucose absorption
New drug for NIDDM differs from sulfonylureas
A new oral drug for managing noninsulin-dependent diabetes mellitus (NIDDM), miglitol (Glyset), works by delaying the digestion of ingested carbohydrates, thereby resulting in a smaller risk in blood glucose concentration following meals.
As a consequence of plasma glucose reduction, miglitol reduces levels of glycosylated hemoglobin in patients with NIDDM.
In contrast to sulfonylureas, miglitol doesn’t enhance insulin secretion. Its antihyperglycemic action results from a reversible inhibition of membrane-bound intestinal enzymes, which delays glucose absorption and lowers postprandial hyperglycemia.
When used with sulfonylureas, miglitol enhances glycemic control in patients. It also diminishes the insulinotropic and weight-increasing effects of sulfonylureas.
Because miglitol is excreted primarily by the kidneys, accumulation of the drug is expected in patients with renal impairment. Patients with a creatinine clearance level of less than 25 ml/min taking 25 mg three times daily have a more than two-fold increase in miglitol plasma levels compared to patients with creatinine clearance levels of greater than 60 ml/min. Dosage adjustments to correct increased plasma concentrations isn’t feasible because miglitol acts locally.
Miglitol doesn’t influence hepatic function because it is not metabolized.
Elderly unaffected by drug
The drug doesn’t appear to affect elderly patients differently than younger patients. The pharmacokinetics of miglitol were studied in both elderly patients and young males, and at a dosage of 100 mg three times daily for three days, there were no differences noted between the two groups.
There were two U.S. and three overseas controlled, fixed-dose, monotherapy studies of the drug to evaluate its efficacy. In study one, there was a statistically significant smaller increase in mean glycosylated hemoglobin (HbA1c) over time in the miglitol group (50 mg three times daily) compared to patients on placebo. Significant reductions in mean fasting and postprandial plasma glucose levels and in mean postprandial insulin levels were observed in miglitol-treated patients compared with patients on placebo.
Postprandial glucose levels reduced
In a second 14-week study, there was a significant decrease in HbA1c in patients receiving miglitol, 50 mg three times daily, compared to placebo. There also were significant reductions in postprandial plasma glucose and postprandial serum insulin levels compared to placebo.
In study three of a six-month, dose-ranging trial evaluating miglitol at doses from 25 mg three times daily to 200 mg three times daily, miglitol produced a greater reduction in HbA1c than placebo at all doses, although the effect was statistically significant only at the 100 mg, three-times daily and 200 mg, three-times daily doses. In addition, all doses of miglitol produced significant reductions in postprandial plasma glucose and postprandial insulin levels compared to placebo.
Two additional studies also found significant reductions in HbA1c and postprandial plasma glucose levels. So did studies of the drug as adjunctive therapy with sulfonylureas.
When initiating miglitol therapy, diet should be emphasized as the primary form of treatment for NIDDM. Exercise also should be encouraged.
Contraindications for some conditions
Miglitol is contraindicated in patients with the following conditions:
• diabetic ketoacidosis;
• inflammatory bowel disease, colonic ulceration, or partial intestinal obstruction and in patients predisposed to intestinal obstruction;
• chronic intestinal diseases associated with marked disorders of digestion or absorption or with conditions that may deteriorate as a result of increased gas formation in the intestine;
• hypersensitivity to the drug or any of its components.
Hypoglycemia did not occur with miglitol alone in clinical trials, but it can occur with miglitol and sulfonylureas when taken together. If hypoglycemia occurs with the use of miglitol and sulfonylureas, oral glucose should be used instead of sucrose to treat it, because miglitol inhibits the absorption of sucrose.
When diabetic patients experience stress such as fever or trauma, a temporary loss of blood glucose control may occur. At that time, temporary insulin therapy may be necessary.
Miglitol therapy in patients with renal impairment is not recommended because long-term clinical trials in patients with significant renal dysfunction haven’t been conducted.
Note possible drug interactions
Drug interactions with miglitol may occur with any of the following agents:
• digoxin;
• ranitidine;
• propranolol;
• intestinal absorbents such as charcoal or digestive enzyme preparations such as amylase.
The safety of miglitol in pregnant patients or children hasn’t been established. It should not be administered to women who are breast-feeding.
The most common adverse reactions with miglitol are as follows:
• abdominal pain;
• diarrhea;
• flatulence;
• skin rash;
• low serum iron levels.
There is no fixed-dosage regimen for miglitol, but patients shouldn’t receive more than the maximum recommended dosage of 100 mg three times daily.
The drug should be taken three times daily at the start (with the first bite) of each main meal. Miglitol should be started at 25 mg and gradually increased. The usual maintenance dose is 5 mg three times daily.
Miglitol is supplied in 25-mg, 50-mg, and 100-mg tablets in bottles of 100 or 1,000. It also is available in unit-dose packages of 100.
[Editor’s note: For more information on miglitol, contact: Professional Services Department, Bayer Corp., Pharmaceutical Division, 400 Morgan Lane, West Haven, CT 06516. Telephone: (800) 468-0894, ext. 2373.]
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