PRECOSE (acarbose tablets)
PRECOSE (acarbose tablets) is an oral alpha-glucosidase inhibitor for use in the management of type 2 diabetes mellitus. Acarbose is an oligosaccharide which is obtained from fermentation processes of a microorganism, Actinoplanes utahensis, and is chemically known as O-4,6-dideoxy- 4-[[(1S,4R,5S,6S)- 4,5,6-trihydroxy-3-(hydroxymethyl)-2-cyclohexen-1-yl]amino]-α-D-glucopyranosyl-(1 → 4)-O-α-Dglucopyranosyl-(1 → 4)-D-glucose. It is a white to off-white powder with a molecular weight of 645.6. Acarbose is soluble in water and has a pKa of 5.1. Its empirical formula is C25 H45 NO18
Acarbose is a complex oligosaccharide that delays the digestion of ingested carbohydrates, thereby resulting in a smaller rise in blood glucose concentration following meals. As a consequence of plasma glucose reduction, PRECOSE reduces levels of glycosylated hemoglobin in patients with type 2 diabetes mellitus. Systemic non-enzymatic protein glycosylation, as reflected by levels of glycosylated hemoglobin, is a function of average blood glucose concentration over time.
Mechanism of Action
In contrast to sulfonylureas, PRECOSE does not enhance insulin secretion. The antihyperglycemic action of acarbose results from a competitive, reversible inhibition of pancreatic alpha-amylase and membrane-bound intestinal alpha-glucoside hydrolase enzymes. Pancreatic alpha-amylase hydrolyzes complex starches to oligosaccharides in the lumen of the small intestine, while the membrane-bound intestinal alpha-glucosidases hydrolyze oligosaccharides, trisaccharides, and disaccharides to glucose and other monosaccharides in the brush border of the small intestine. In diabetic patients, this enzyme inhibition results in a delayed glucose absorption and a lowering of postprandial hyperglycemia.
Because its mechanism of action is different, the effect of PRECOSE to enhance glycemic control is additive to that of sulfonylureas, insulin or metformin when used in combination. In addition, PRECOSE diminishes the insulinotropic and weight-increasing effects of sulfonylureas.
Acarbose has no inhibitory activity against lactase and consequently would not be expected to induce lactose intolerance.
PRECOSE is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus.
PRECOSE is contraindicated in patients with known hypersensitivity to the drug. Precose is contraindicated in patients with diabetic ketoacidosis or cirrhosis. PRECOSE is also contraindicated in patients with inflammatory bowel disease, colonic ulceration, partial intestinal obstruction or in patients predisposed to intestinal obstruction. In addition, PRECOSE is contraindicated in patients who have chronic intestinal diseases associated with marked disorders of digestion or absorption and in patients who have conditions that may deteriorate as a result of increased gas formation in the intestine.
Dosage and administration
- There is no fixed dosage regimen for the management of diabetes mellitus with PRECOSE or any other pharmacologic agent.
- Dosage of PRECOSE must be individualized on the basis of both effectiveness and tolerance while not exceeding the maximum recommended dose of 100 mg t.i.d.
- PRECOSE should be taken three times daily at the start (with the first bite) of each main meal. PRECOSE should be started at a low dose, with gradual dose escalation as described below, both to reduce gastrointestinal side effects and to permit identification of the minimum dose required for adequate glycemic control of the patient.
- If the prescribed diet is not observed, the intestinal side effects may be intensified. If strongly distressing symptoms develop in spite of adherence to the diabetic diet prescribed, the doctor must be consulted and the dose temporarily or permanently reduced.
The recommended starting dosage of PRECOSE is 25 mg given orally three times daily at the start (with the first bite) of each main meal. However, some patients may benefit from more gradual dose titration to minimize gastrointestinal side effects. This may be achieved by initiating treatment at 25 mg once per day and subsequently increasing the frequency of administration to achieve 25 mg t.i.d.
Once a 25 mg t.i.d. dosage regimen is reached, dosage of PRECOSE should be adjusted at 4–8 week intervals based on one-hour postprandial glucose or glycosylated hemoglobin levels, and on tolerance. The dosage can be increased from 25 mg t.i.d. to 50 mg t.i.d. Some patients may benefit from further increasing the dosage to 100 mg t.i.d. The maintenance dose ranges from 50 mg t.i.d. to 100 mg t.i.d. However, since patients with low body weight may be at increased risk for elevated serum transaminases, only patients with body weight > 60 kg should be considered for dose titration above 50 mg t.i.d.
If no further reduction in postprandial glucose or glycosylated hemoglobin levels is observed with titration to 100 mg t.i.d., consideration should be given to lowering the dose. Once an effective and tolerated dosage is established, it should be maintained.
The maximum recommended dose for patients ≤ 60 kg is 50 mg t.i.d. The maximum recommended dose for patients > 60 kg is 100 mg t.i.d.
Patients Receiving Sulfonylureas or Insulin
Sulfonylurea agents or insulin may cause hypoglycemia. PRECOSE given in combination with a sulfonylurea or insulin will cause a further lowering of blood glucose and may increase the potential for hypoglycemia. If hypoglycemia occurs, appropriate adjustments in the dosage of these agents should be made.
Macrovascular Outcomes: There have been no clinical studies establishing conclusive evidence of macrovascular risk reduction with PRECOSE or any other anti-diabetic drug.
Because of its mechanism of action, PRECOSE when administered alone should not cause hypoglycemia in the fasted or postprandial state. Sulfonylurea agents or insulin may cause hypoglycemia. Because PRECOSE given in combination with a sulfonylurea or insulin will cause a further lowering of blood glucose, it may increase the potential for hypoglycemia. Hypoglycemia does not occur in patients receiving metformin alone under usual circumstances of use, and no increased incidence of hypoglycemia was observed in patients when PRECOSE was added to metformin therapy. Oral glucose (dextrose), whose absorption is not inhibited by PRECOSE, should be used instead of sucrose (cane sugar) in the treatment of mild to moderate hypoglycemia. Sucrose, whose hydrolysis to glucose and fructose is inhibited by PRECOSE, is unsuitable for the rapid correction of hypoglycemia. Severe hypoglycemia may require the use of either intravenous glucose infusion or glucagon injection.
Elevated Serum Transaminase Levels
In long-term studies (up to 12 months, and including PRECOSE doses up to 300 mg t.i.d.) conducted in the United States, treatment-emergent elevations of serum transaminases (AST and/or ALT) above the upper limit of normal (ULN), greater than 1.8 times the ULN, and greater than 3 times the ULN occurred in 14%, 6%, and 3%, respectively, of PRECOSE-treated patients as compared to 7%, 2%, and 1%, respectively, of placebo-treated patients. Although these differences between treatments were statistically significant, these elevations were asymptomatic, reversible, more common in females, and, in general, were not associated with other evidence of liver dysfunction. In addition, these serum transaminase elevations appeared to be dose related. In US studies including PRECOSE doses up to the maximum approved dose of 100 mg t.i.d., treatment-emergent elevations of AST and/or ALT at any level of severity were similar between PRECOSE-treated patients and placebo-treated patients (p ≥ 0.496).
Loss of Control of Blood Glucose
When diabetic patients are exposed to stress such as fever, trauma, infection, or surgery, a temporary loss of control of blood glucose may occur. At such times, temporary insulin therapy may be necessary.
Plasma concentrations of PRECOSE in renally impaired volunteers were proportionally increased relative to the degree of renal dysfunction. Long-term clinical trials in diabetic patients with significant renal dysfunction (serum creatinine > 2.0 mg/dL) have not been conducted. Therefore, treatment of these patients with PRECOSE is not recommended.
Use in specific populations
Pregnancy: Pregnancy Category B. The safety of PRECOSE in pregnant women has not been established.
Nursing Mothers: A small amount of radioactivity has been found in the milk of lactating rats after administration of radiolabeled acarbose. It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, PRECOSE should not be administered to a nursing woman.
Pediatric Use: Safety and effectiveness of PRECOSE in pediatric patients have not been established.
Geriatric Use: Of the total number of subjects in clinical studies of PRECOSE in the United States, 27% were 65 and over, while 4% were 75 and over. No overall differences in safety and effectiveness were observed between these subjects and younger subjects. The mean steady-state area under the curve (AUC) and maximum concentrations of acarbose were approximately 1.5 times higher in elderly compared to young volunteers; however, these differences were not statistically significant.
- Gastrointestinal: abdominal pain, diarrhea, and flatulence
- Elevated Serum Transaminase Levels
- Small reductions in hematocrit occurred more often in PRECOSE-treated patients than in placebotreated patients but were not associated with reductions in hemoglobin. Low serum calcium and low plasma vitamin B levels were associated with PRECOSE therapy but are thought to be either spurious or of no clinical significance.
- Additional adverse events reported from worldwide postmarketing experience include fulminant hepatitis with fatal outcome, hypersensitive skin reactions (for example rash, erythema, exanthema and uticaria), edema, ileus/subileus, jaundice and/or hepatitis and associated liver damage, thrombocytopenia, and pneumatosis cystoides intestinalis
- There have been rare postmarketing reports of pneumatosis cystoides intestinalis associated with the use of alpha-glucosidase inhibitors, including Precose. Pneumatosis cystoides intestinalis may present with symptoms of diarrhea, mucus discharge, rectal bleeding, and constipation. Complications may include pneumoperitoneum, volvulus, intestinal obstruction, intussusception, intestinal hemorrhage, and intestinal perforation. If pneumatosis cystoides intestinalis is suspected, discontinue Precose and perform the appropriate diagnostic imaging.
Unlike sulfonylureas or insulin, an overdose of PRECOSE will not result in hypoglycemia. An overdose may result in transient increases in flatulence, diarrhea, and abdominal discomfort which shortly subside. In cases of overdosage the patient should not be given drinks or meals containing carbohydrates (polysaccharides, oligosaccharides and disaccharides) for the next 4–6 hours.