Tolbutamide

A to Z Drug Facts

Tolbutamide

	Action
	Indications
	Contraindications
	Route/Dosage
	Interactions
	Lab Test Interferences
	Adverse Reactions
	Precautions
Patient Care Considerations
	Administration/Storage
	Assessment/Interventions
	Patient/Family Education

(tole-BYOO-tuh-mide)

Orinase, Orinase Diagnostic, Apo-Tolbutamide, Novo-Butamide

Class: Antidiabetic/sulfonylurea

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

Indications

Oral form: 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. IV form (tolbutamide sodium): Aid in diagnosis of pancreatic islet cell adenoma.

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

Route/Dosage

ADULTS: PO Usually 1–2 g/day (range, 0.25–3 g) in 1–2 divided doses.

For Diagnostic Purposes

ADULTS: IV 1 g over 2–3 min.

Interactions

Androgens, anticoagulants, azole antifungals, chloramphenicol, clofibrate, dicumarol, fenfluramine, fluconazole, gemfibrozil, histamine H₂ ntagonists, magnesium salts, methyldopa, MAO inhibitors, phenylbutazone, probenecid, salicylates, sulfinpyrazone, sulfonamides, tricyclic antidepressants, urinary acidifiers: May increase 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: May decrease hypoglycemic effect. Charcoal: Charcoal can reduce the absorption of sulfonylureas; depending on the clinical situation, this will reduce their efficacy or toxicity. Digitalis glycosides: Concurrent administration may result in increased digitalis serum levels. Digoxin: May cause increased digoxin serum concentrations. Ethanol: May cause disulfiram-like reaction.

Lab Test Interferences Drug may cause false-positive reaction for albumin with acidification-after-boiling test; no interference occurs with sulfosalicyclic acid test. Elevated LFTs and elevations in BUN and creatinine may occur.

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; porphyria; photosensitivity. EENT: Tinnitus. GI: Nausea; epigastric fullness; heartburn. HEMA: Leukopenia; thrombocytopenia; aplastic anemia; agranulocytosis; emolytic anemia; pancytopenia. HEPA: Cholestatic jaundice. META: Hypoglycemia; SIADH with water retention and dilutional hyponatremia, especially in patients with CHF or hepatic cirrhosis. OTHER: Disulfiram-like reaction; weakness; paresthesia; fatigue; malaise; light burning sensation along course of vein during IV injection; thrombophlebitis with thrombosis of injected vein.

Precautions

Pregnancy: Category C. Insulin is recommended to control elevated blood glucose levels during pregnancy. Lactation: Excreted into breast milk. Children: Safety and efficacy have not been established. Elderly or debilitated patients: Particularly susceptible to hypoglycemic action. Hypoglycemia may be difficult to recognize in elderly. Disulfiram-like syndrome: Administration of drug with alcohol may induce facial flushing and breathlessness. Hepatic and renal impairment: Use drug with caution. Cardiovascular risk: Patients treated for 5 to 8 years with diet plus tolbutamide (1.5 g/day) ad a rate of cardiovascular mortality » 2.5 times that of patients treated with diet alone.

PATIENT CARE CONSIDERATIONS

Administration/Storage

Administer 30 min prior to meal. May administer with food if GI upset occurs.
May administer total dose in morning or give in divided doses to decrease GI upset or to decrease blood glucose fluctuation.
Inject at constant rate over 2–3 min.
Refer to manufacturer's product information for specific test methodology and interpretation of test results.
Use within 1 hr of reconstitution but only if solution is complete and clear.

Assessment/Interventions

Obtain patient history, including drug history and any known allergies. Note diabetes complicated by ketoacidosis, decreased renal or hepatic function or sensitivity to sulfa drugs.
If renal or hepatic function is diminished, use cautiously and monitor function.
Monitor elderly closely for hypoglycemic effects.
Monitor vital signs, blood sugar, weight and I&O daily.
If jaundice occurs, discontinue drug and notify physician.

OVERDOSAGE: SIGNS & SYMPTOMS
	Hypoglycemia including symptoms of the following: Tingling of lips and tongue, nausea, lethargy, confusion, agitation, nervousness, tachycardia, sweating, tremor, hunger, convulsions, stupor, coma

Patient/Family Education

Instruct patient to follow the diet and exercise regimen prescribed by physician.
Inform patient of symptoms of and treatment for low blood sugar and advise patient to carry source of sugar at all times.
Instruct patient to avoid alcohol. Inform patient that alcohol may react with tolbutamide and cause antabuse-like reaction (flushing, headache, dizziness, high BP).
Instruct patient to monitor weight and to inform physician if steady weight gain occurs.
Inform patient that surgery, illness or trauma may require temporary use of insulin.
Instruct patient to alert physician to following problems: Nausea, vomiting, GI distress, diarrhea, fever, sore throat, rash, itching, weakness, unusual bruising or bleeding, spilling of glucose or ketones in urine.
Caution patient to avoid exposure to sunlight and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.
Recommended that patient carry identification card (eg, Medi-Alert) indicating condition and drug therapy.