Why It Is Used

Sulfonylurea medications are prescribed when changes in diet, weight loss, and exercise do not keep the blood sugar level within a safe range. When taking one of these medications, it is still important to eat a balanced diet, exercise, and lose weight if needed.

These medications can help control blood sugar levels in children and young adults who have type 2 diabetes and are overweight.

Sulfonylurea medications are not safe if you:

* Are pregnant or trying to become pregnant. They may harm the fetus.
* Have liver or kidney problems. Sulfonylurea medications are broken down by the liver and pass out of the body through urine produced in the kidneys.

Tell your doctor if you have had a serious allergic reaction to a sulfa antibiotic, such as Bactrim or Septra. You may not be able to use a sulfonylurea.

How Well It Works

Sulfonylurea medications work rapidly to control elevated blood sugar levels; they often are the first medication selected to treat people newly diagnosed with type 2 diabetes. Metformin is preferred for initial treatment because it doesn't cause low blood sugar or weight gain. The great majority of people have better control of their blood sugar by using a sulfonylurea medication along with diet and exercise than by using diet and exercise alone.

However, the medication may become less effective after several years of use. Some people who no longer respond to one sulfonylurea may respond to a different one.

Results of the United Kingdom Prospective Diabetes Study (UKPDS) showed that sulfonylurea medications:

* Were as effective as metformin and insulin in reducing blood sugar levels of people with type 2 diabetes.1
* Decreased the risk for complications of the eyes (retinopathy), kidneys (nephropathy), and nerves (neuropathy).2

Sulfonylurea medications do not decrease fat (triglycerides) in the blood as does metformin.

What To Think About

Sulfonylurea medications are an effective treatment for many people with type 2 diabetes. If one of these medications keeps your blood sugar within a safe range, your risks of long-term complications of diabetes can be reduced. Other important factors that contribute to complications include high blood pressure, being overweight, high cholesterol levels, and smoking.

Few studies have been done on the use of oral medications for type 2 diabetes in children, and they have not been approved by the U.S. Food and Drug Administration (FDA) for use in children. But because these oral medications are safe for adults, most health professionals use them to treat children with type 2 diabetes.

Approval of FDA

The first combination oral antihyperglycemic agent was recently approved by the Food and Drug Administration (FDA). Glucovance™, a combination of glyburide and metformin, is manufactured by Bristol-Myers Squibb. It is FDA-approved as first-line therapy for patients with Type 2 diabetes mellitus (DM) whose glucose is not controlled with diet and exercise. It can also be used as second-line therapy for patients whose blood glucose levels are not controlled with either a sulfonylurea or metformin alone.

Each individual component of Glucovance™ has its own unique mechanism of action. Glyburide, a sulfonylurea, lowers blood glucose by stimulating the pancreas to secrete insulin. Metformin, a biguanide, works by decreasing gluconeogenesis and intestinal glucose absorption, as well as enhancing insulin sensitivity.

Some common adverse effects associated with Glucovance™ include diarrhea, upper respiratory infection, lightheadedness, dizziness, shaking, hunger, and headache. Additionally, due to the metformin component, Glucovance™ may cause lactic acidosis, a rare but serious adverse effect. The risk of lactic acidosis increases with patient age and degree of renal insufficiency. To avoid lactic acidosis, it is recommended to 1) monitor renal function, 2) use the lowest dose possible of the metformin component, and 3) do not initiate its use in patients 80 years of age or older. Glucovance™ also has the potential to cause hypoglycemia because it stimulates insulin secretion. The risk is greatest in patients with decreased caloric intake, those taking concurrent glucose-lowering medications, or those ingesting alcohol.

Caution should be exercised when initiating or discontinuing agents that may cause hypoglycemia (e.g., nonsteroidal anti-inflammatory agents, warfarin, beta blockers) or hyperglycemia (e.g., diuretics, steroids, phenytoin, estrogens, calcium channel blockers) while patients are receiving Glucovance™. Drug interactions may also occur between metformin and agents that are excreted by renal tubular secretion (e.g., digoxin, procainamide, amiloride, quinidine, vancomycin).

Glucovance™ is contraindicated when serum creatinine levels are 1.5 mg/dL or higher in males or 1.4 mg/dL or higher in females, hypersensitivity to either component, kidney dysfunction, congestive heart failure, and acute or chronic metabolic acidosis.

If the patient's current combination therapy (e.g., glyburide [or another sulfonylurea] plus metformin) is changed to Glucovance™, the dose should not exceed the daily dose of sulfonylurea and metformin already being taken. See Table 1 for specific dosing recommendations of Glucovance™.

There are three tablet strengths of Glucovance™ available: 1.25 mg/250 mg (glyburide/metformin), 2.5 mg/500 mg, and 5 mg/500 mg. Based on the average wholesale price (AWP), the costs are approximately $0.66, $0.78, and $0.78 per tablet, respectively.

There are advantages for combining glyburide and metformin: 1) lower doses are required for glucose control, 2) fewer adverse effects may occur, and 3) increase in patient acceptance and compliance. In addition, patients should maintain a good diet and exercise program, as well as regular blood glucose monitoring.