Sulfonylurea antidiabetic agents (also known as sulfonylureas) are used to treat a certain type of diabetes mellitus (sugar diabetes) called type 2 diabetes. When you have type 2 diabetes, insulin is still being produced by your pancreas. Sometimes the amount of insulin you produce may not be enough or your body may not be using it properly and you may still need more. Sulfonylureas work by causing your pancreas to release more insulin into the blood stream. All of the cells in your body need insulin to help turn the food you eat into energy. This is done by using sugar (or glucose) in the blood as quick energy. Or the sugar may be stored in the form of fats, sugars, and proteins for use later, such as for energy between meals.

Sometimes insulin that is being produced by the body is not able to help sugar get inside the body's cells. Sulfonylureas help insulin get into the cells where it can work properly to lower blood sugar. In this way, sulfonylureas will help lower blood sugar and help restore the way you use food to make energy.

Many people with type 2 diabetes can control their blood sugar level with diet or diet and exercise alone. Following a diabetes diet plan and exercising will always be important with any type of diabetes. To work properly, the amount of sulfonylurea you use must be balanced against the amount and type of food you eat and the amount of exercise you do. If you change your diet, your exercise, or both, you will want to test your blood sugar level so that it does not drop too low (hypoglycemia) or rise too high (hyperglycemia). Your health care professional will teach you what to do if this happens.

Sometimes patients with type 2 diabetes might need to change to treatment with insulin for a short period of time during pregnancy or for a serious medical condition, such as diabetic coma; ketoacidosis; severe injury, burn, or infection; or major surgery. In these conditions, insulin and blood sugar can change fast and blood sugar can be best controlled with insulin instead of a sulfonylurea.

At some point, a sulfonylurea may stop working as well and your blood sugar level will go up. You will need to know if this happens and what to do. Instead of taking more of this medicine, your doctor may change you to another sulfonylurea. Or your doctor may have you inject small doses of insulin or take another oral antidiabetic medicine called metformin along with your sulfonylurea to help the insulin you make work better. If that does not bring down the amount of sugar in your blood, your doctor may have you stop taking the oral antidiabetic agents and begin receiving only insulin injections.

Chlorpropamide may also be used for other conditions as determined by your doctor.

Oral antidiabetic medicines do not help diabetic patients who have type 1 diabetes because these patients cannot produce or release insulin from their pancreas gland. Their blood sugar is best controlled by insulin injections.

Sulfonylureas are available only with your doctor's prescription, in the following dosage forms:

• Oral

• Acetohexamide

  • Tablets (U.S. and Canada)

• Chlorpropamide

  • Tablets (U.S. and Canada)

• Gliclazide

  • Tablets (Canada)

• Glimepiride

  • Tablets (U.S.)

• Glipizide

  • Tablets (U.S.)
  • Extended-release Tablets (U.S.)

• Glyburide

  • Tablets (U.S. and Canada)
  • Micronized Tablets (U.S.)

• Tolazamide

  • Tablets (U.S.)

• Tolbutamide

  • Tablets (U.S. and Canada)

Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For sulfonylurea medicines, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to sulfonylureas, or to sulfonamide-type (sulfa) medicines, including thiazide diuretics (a certain type of water pill). Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Sulfonylureas are rarely used during pregnancy. The amount of insulin you need changes during and after pregnancy. For this reason, it is easier to control your blood sugar using injections of insulin, rather than with the use of sulfonylureas. Close control of your blood sugar can reduce your chance of having high blood sugar during the pregnancy and of your baby gaining too much weight, or having birth defects. Be sure to tell your doctor if you plan to become pregnant or if you think you are pregnant. If insulin is not available or cannot be used and sulfonylureas are used during pregnancy, they should be stopped at least 2 weeks before the delivery date (one month before for chlorpropamide and glipizide). Glimepiride should not be used at all during pregnancy. Lowering of blood sugar can occur as a rebound effect at delivery and for several days following birth and will be watched closely by your health care professionals.

Breast-feeding—Chlorpropamide and tolbutamide pass into human breast milk and glimepiride passes into the milk of rats. Chlorpropamide is not recommended in nursing mothers but, in some cases, tolbutamide has been used. Nursing mothers should not take glimepiride. It is not known if other sulfonylureas pass into breast milk. Check with your doctor if you are thinking about breast-feeding.

Children—There is little information about the use of sulfonylureas in children. Type 2 diabetes is unusual in this age group.

Older adults—Some elderly patients may be more sensitive than younger adults to the effects of sulfonylureas, especially when more than one antidiabetic medicine is being taken or if other medicines that affect blood sugar are also being taken. This may increase your chance of developing low blood sugar during treatment. Furthermore, the first signs of low or high blood sugar are not easily seen or do not occur at all in older patients. This may increase the chance of low blood sugar developing during treatment.

Also, elderly patients who take chlorpropamide are more likely to hold too much body water.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Do not take any other medicine, unless prescribed or approved by your doctor . When you are taking sulfonylurea antidiabetic drugs, it is especially important that your health care professional know if you are taking any of the following:

• Alcohol—When low blood sugar occurs, it may last longer than usual if more than a small amount of alcohol is taken, especially on an empty stomach. Small amounts of alcohol at mealtime usually do not cause problems with your blood sugar but may cause a redness (called flushing) in the face, arms, and neck that can be uncomfortable. This can occur with most of the sulfonylureas but is most likely to occur with chlorpropamide and has occurred up to 12 hours after alcohol was taken during chlorpropamide use

• Anticoagulants (blood thinners)—The effect of either the blood thinner or the antidiabetic medicine may be increased or decreased if the two medicines are used together

• Aspirin or other salicylates or
• Azole antifungals (miconazole [e.g., Monistat I.V.], fluconazole [e.g., Diflucan]) or
• Chloramphenicol (e.g., Chloromycetin) or
• Cimetidine (e.g., Tagamet) or
• Fluoroquinolones (ciprofloxacin [e.g., Cipro], enoxacin [e.g., Penetrex], lomefloxacin [e.g., Maxaquin], norfloxacin [e.g., Noroxin], ofloxacin [e.g., Floxin]) or
• Quinidine (e.g., Quinidex) or
• Quinine or
• Ranitidine (e.g., Zantac)—These medicines may increase the chances of low blood sugar

• Asparaginase (e.g., Elspar) or
• Corticosteroids (cortisone-like medicine) or
• Lithium (e.g., Lithonate) or
• Thiazide diuretics (e.g., Dyazide)—These medicines may increase the chances of high blood sugar

• Asthma medicines or
• Cough or cold medicines or
• Hay fever or allergy medicines—Many medicines (including nonprescription [over-the-counter] products) can affect the control of your blood sugar

• Beta-adrenergic blocking agents (acebutolol [e.g., Sectral], atenolol [e.g., Tenormin], betaxolol [e.g., Kerlone], bisoprolol [e.g., Zebeta], carteolol [e.g., Cartrol], labetalol [e.g., Normodyne], metoprolol [e.g., Lopressor], nadolol [e.g., Corgard], oxprenolol [e.g., Trasicor], penbutolol [e.g., Levatol], pindolol [e.g., Visken], propranolol [e.g., Inderal], sotalol [e.g., Betapace], timolol [e.g., Blocadren])—Beta-adrenergic blocking agents may increase the chance that high or low blood sugar can occur. Also, they can hide symptoms of low blood sugar (such as fast heartbeat). Because of this, a person with diabetes might not recognize that he or she has low blood sugar and might not take immediate steps to treat it. Beta-adrenergic blocking agents can also cause low blood sugar to last longer than usual

• Cyclosporine [e.g., Sandimmune]—Sulfonylureas can increase the effects of cyclosporine

• Guanethidine (e.g., Ismelin) or
• Monoamine oxidase (MAO) inhibitor activity (isocarboxazid [e.g., Marplan], isocarboxazid [e.g., Marplan], phenelzine [e.g., Nardil], procarbazine [e.g., Matulane], selegiline [e.g., Eldepryl], or tranylcypromine [e.g., Parnate])—Taking a sulfonylurea while you are taking (or within 2 weeks of taking) these medicines may increase the chances of low blood sugar occurring

• Octreotide (e.g., Sandostatin) or
• Pentamidine (e.g., Pentam)—Use of these medicines with sulfonylureas may increase the chance of either high or low blood sugar occurring

Other medical problems—The presence of other medical problems may affect the use of the sulfonylurea antidiabetic medicines. Make sure you tell your doctor if you have any other medical problems, especially:

• Acid in the blood (acidosis) or
• Burns (severe) or
• Diabetic coma or
• Fever, high or
• Injury, severe or
• Ketones in the blood (diabetic ketoacidosis) or
• Surgery, major or
• Any other condition in which insulin needs change rapidly—Insulin may be needed temporarily to control diabetes in patients with these conditions because changes in blood sugar may occur rapidly and without much warning; also, your blood sugar may need to be tested more often

• Diarrhea, continuing or
• Female hormone changes for some women (e.g., during puberty, pregnancy, or menstruation) or
• Infection, severe or
• Mental stress, severe or
• Overactive adrenal gland, not properly controlled or
• Problems with intestines, severe or
• Slow stomach emptying or
• Vomiting, continuing or
• Any other condition that causes severe blood sugar changes—Insulin may be needed temporarily to control diabetes mellitus in patients with these conditions because changes in blood sugar may occur rapidly and without much warning; also, your blood sugar may need to be tested more often

• Heart disease—Chlorpropamide or tolbutamide causes some patients to retain (keep) more body water than usual. Heart disease may be worsened by this extra body water

• Kidney disease or
• Liver disease—Your blood sugar may be increased or decreased, partly because of slower removal of sulfonylurea from the body; this may change the amount of sulfonylurea you need

• Overactive thyroid, not properly controlled or
• Underactive thyroid, not properly controlled—Your blood sugar may be increased or decreased, partly because the medicine may be removed from the body too fast or too slow. Until your thyroid condition is controlled, the amount of sulfonylurea you need may change. Also, your blood sugar may need to be tested more often

• Underactive adrenal gland, not properly controlled or
• Underactive pituitary gland, not properly controlled or
• Undernourished condition or
• Weakened physical condition or
• Any other condition that causes low blood sugar—Patients with these conditions may be more likely to develop low blood sugar while taking sulfonylureas