Tolazamide

A to Z Drug Facts

 Action Decreases blood glucose by stimulating release of insulin from pancreas.

 Indications Adjunct to diet to lower blood glucose in patients with non-insulin-dependent diabetes mellitus (type II) whose hyperglycemia cannot be controlled by diet alone. Unlabeled use(s): Temporary adjunct to insulin therapy in selected patients with non-insulin-dependent diabetes mellitus to improve diabetic control.

 Contraindications Hypersensitivity to sulfonylureas; diabetes complicated by ketoacidosis, with or without coma; sole therapy of insulin-dependent (type I) diabetes mellitus; gestational diabetes.

 Route/Dosage

ADULTS: PO 100–250 mg/day with breakfast or first main meal. If fasting blood sugar (BS) is < 200 mg/dl, initial dose is 100 mg/day or if FBS is > 200 mg/dl, initial dose is 250 mg/day. In malnourished, underweight, elderly patients use 100 mg/day. May adjust dose by 100–250 mg/wk as needed to maximum 1000 mg/day. If > 500 mg/day is required, give in divided doses twice daily. Doses > 1 g/day are not likely to improve control. MAINTENANCE DOSE: PO Usual dose is 100 to 1000 mg/day with the average being 250 to 500 mg/day. Following initiation of therapy, dosage adjustment is made in increments of 100 to 250 mg at weekly intervals based on patient's blood glucose response.

 Interactions

Androgens, anticoagulants, azole antifungals, chloramphenicol, clofibrate, fenfluramine, fluconazole, gemfibrozil, histamine H₂ antagonists, magnesium salts, methyldopa, MAO inhibitors, phenylbutazone, probenecid, salicylates, sulfinpyrazone, sulfonamides, tricyclic antidepressants, urinary acidifiers: Increased hypoglycemic effect. Beta-blockers, calcium channel blockers, cholestyramine, corticosteroids, diazoxide, estrogens, hydantoins, isoniazid, nicotinic acid, oral contraceptives, phenothiazines, rifampin, sympathomimetics, thiazide diuretics, thyroid agents, urinary alkalinizers: Decreased hypoglycemic effect. Charcoal: Charcoal can reduce the absorption; depending on clinical situation, this will reduce sulfonylureas efficacy or toxicity. Digitalis glycosides: Concurrent administration may result in increased digitalis serum levels.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Increased risk of cardiovascular mortality. CNS: Dizziness; vertigo. DERM: Allergic skin reactions; eczema; pruritus; erythema; urticaria; orbilliform or maculopapular eruptions; lichenoid reactions. GI: Nausea; epigastric fullness; heartburn; cholestatic jaundice. GU: Mild diuresis. HEMA: Leukopenia; thrombocytopenia; aplastic anemia; agranulocytosis; emolytic anemia; pancytopenia; hepatic porphyria. META: Hypoglycemia. OTHER: Disulfiram-like reaction; weakness; paresthesia; fatigue; malaise.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Children: Safety and efficacy in children not established. Elderly and debilitated patients: Elderly and debilitated patients are particularly susceptible to hypoglycemic action of sulfonylureas. Hypoglycemia: Tolazamide may produce severe hypoglycemia, which may be more difficult to recognize in elderly or in patients receiving beta-blockers. Disulfiram-like syndrome: Administration with alcohol may include facial flushing reaction and occasional breathlessness. This reaction has been reported more commonly with other sulfonylureas. Hepatic and renal impairment: Use drug with caution and monitor liver and renal function frequently. Hyperglycemia: Hyperglycemia is major risk factor in development of diabetic complications. Measurement of glycosylated hemoglobin and self-monitoring of blood glucose are useful. Loss of blood glucose control: Stress (including fever, trauma, infection or surgery) or secondary failure (wherein drug's effectiveness in lowering blood glucose diminishes over time) may precipitate loss of blood glucose control.

 Administration/Storage

• Give with breakfast or with first meal of day.
• Crush tablet if patient unable to swallow tablet whole.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Closely monitor glucose control in elderly patients and promptly adjust dose if hypoglycemia is noted.
• Initially monitor blood glucose and urine ketones three times a day. Once glucose control is established monitor less often in type II diabetic patients.

 Patient/Family Education

• Teach signs and symptoms of hypoglycemia (profuse sweating, excessive hunger, weakness, dizziness, tremor, tachycardia, anxiety, numbness of extremities) nd of hyperglycemia (excessive thirst or urination, urinary glucose or ketones, fever, sore throat, unusual bleeding or rash). Remind patient to keep source of quick-acting sugar available at all times.
• When adjusting the dose, tell patient to check urine for ketones and blood for glucose three times a day; 1–2 times a day after stable control is established. Tell patient to notify physician if planning surgery or experiencing vomiting, injury, infection or fever.
• Demonstrate correct technique for performing blood glucose and urine glucose and ketone tests, and ensure correct return demonstrations.
• Tell patient to report repeated abnormal glucose or ketone results to physician.
• Emphasize importance of continuing diet restrictions and exercise regimen.
• Caution about disulfiram-like syndrome (facial flushing, abdominal cramping, nausea) when consuming alcohol. Advise patient to avoid alcohol.
• Inform patient that therapy will not cure disease.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts