glipizide

Action

Lowers blood glucose level by stimulating insulin release from pancreas, increasing insulin sensitivity at receptor sites, and decreasing hepatic glucose production. Also increases peripheral tissue sensitivity to insulin and causes mild diuresis.

Availability

Tablets: 5 mg, 10 mg

Tablets (extended-release): 5 mg, 10 mg

Indications and dosages

➣ To control blood glucose in type 2 (non-insulin-dependent) diabetes mellitus in patients who have some pancreatic function and don't respond to diet therapy

Adults: 5 mg/day P.O. initially, increased as needed after several days (range is 2.5 to 40 mg/day). Give extended-release tablet once daily; maximum dosage is 20 mg/day. Give daily dosage above 15 mg in two divided doses.

➣ Conversion from insulin therapy

Adults: With insulin dosage above 20 units/day, start with usual glipizide dosage and reduce insulin dosage by 50%. With insulin dosage of 20 units/day or less, insulin may be discontinued when glipizide therapy starts.

Dosage adjustment

• Hepatic or renal impairment

• Elderly patients

Contraindications

• Hypersensitivity to drug

• Severe renal, hepatic, thyroid, or other endocrine disease

• Uncontrolled infection, serious burns, or trauma

• Diabetic ketoacidosis

• Pregnancy or breastfeeding

Precautions

Use cautiously in:

• mild to moderate hepatic, renal, or cardiovascular disease; impaired thyroid, pituitary, or adrenal function

• elderly patients.

Administration

• Check baseline creatinine level for normal renal function before giving first dose.

• Give daily dose (extended-release) at breakfast.

• Administer immediate-release tablets 30 minutes before a meal (preferably breakfast). If patient takes two daily doses, give second dose before dinner.

Adverse reactions

CNS: dizziness, drowsiness, headache, weakness

CV: increased CV mortality risk

EENT: blurred vision

GI: nausea, vomiting, diarrhea, constipation, cramps, heartburn, epigastric distress, anorexia

Hematologic: aplastic anemia, agranulocytosis, leukopenia, pancytopenia, thrombocytopenia

Hepatic: cholestatic jaundice, hepatitis

Metabolic: hyponatremia, hypoglycemia

Skin: rash, pruritus, erythema, urticaria, eczema, angioedema, photosensitivity

Other: increased appetite

Interactions

Drug-drug. Androgens (such as testosterone), chloramphenicol, clofibrate, guanethidine, MAO inhibitors, nonsteroidal anti-inflammatory drugs (except diclofenac), salicylates, sulfonamides, tricyclic antidepressants: increased risk of hypoglycemia

Beta-adrenergic blockers: altered response to glipizide, requiring dosage change; prolonged hypoglycemia (with nonselective beta blockers)

Calcium channel blockers, corticosteroids, estrogens, hydantoins, hormonal contraceptives, isoniazid, nicotinic acid, phenothiazines, phenytoin, rifampin, sympathomimetics, thiazide diuretics, thyroid preparations: decreased hypoglycemic effect

Warfarin: initially increased, then decreased, effects of both drugs

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, bilirubin, blood urea nitrogen, cholesterol: increased values

Glucose, granulocytes, hemoglobin, platelets, white blood cells: decreased values

Drug-herbs. Aloe (oral), bitter melon, burdock, chromium, coenzyme Q10, dandelion, eucalyptus, fenugreek: additive hypoglycemic effects

Glucosamine: impaired glycemic control

Drug-behaviors. Alcohol use: disulfiram-like reaction

Patient monitoring

• Monitor blood glucose level, especially during periods of increased stress.

• Evaluate CBC and renal function tests.

• If patient is ill or has abnormal laboratory values, monitor electrolyte, ketone, glucose, pH, lactate dehydrogenase, and pyruvate levels.

• Monitor cardiovascular status.

Patient teaching

• Advise patient to take daily dose of extended-release tablets with breakfast or immediate-release tablet 30 minutes before breakfast (and second dose, if prescribed, before dinner).

• Advise patient to monitor blood glucose level as instructed by prescriber.

• Tell patient he may need supplemental insulin during times of stress or when he can't maintain adequate oral intake.

• Teach patient how to recognize signs and symptoms of hypoglycemia and hyperglycemia.

• Stress importance of diet and exercise to help control diabetes.

• Instruct patient to wear or carry medical identification describing his condition.

• Advise patient to keep sugar source at hand at all times in case of hypoglycemia.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• Tell patient he'll undergo regular blood testing during therapy.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.