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Related to Orinase: Micronase


trademark for a preparation of tolbutamide, an oral hypoglycemic agent.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


(tole-byoo-ta-mide) ,


(trade name)


Therapeutic: antidiabetics
Pharmacologic: sulfonylureas
Pregnancy Category: C


Oral: Control of blood sugar in type 2 diabetes mellitus when diet therapy fails. Requires some pancreatic function.


Lowers blood sugar by stimulating the release of insulin from the pancreas and increasing the sensitivity to insulin at receptor sites.
May also decrease hepatic glucose production.

Therapeutic effects

Lowering of blood sugar in diabetic patients.


Absorption: Well absorbed following oral administration.
Distribution: Unknown.
Protein Binding: 96%.
Metabolism and Excretion: Mostly metabolized by the liver.
Half-life: 7 hr (range 4–25 hr).

Time/action profile (hypoglycemic activity)

PO60 min4–6 hr6–12 hr


Contraindicated in: Hypersensitivity (cross-sensitivity with sulfonamides may occur); Type 1 diabetes; Diabetic coma or ketoacidosis; Severe renal, hepatic, thyroid, or other endocrine disease; Uncontrolled infection, serious burns, or trauma.
Use Cautiously in: Severe cardiovascular disease; Hepatic or renal impairment (↑ risk of hypoglycemia); Infection, stress, or changes in diet may alter requirements for control of blood sugar; Impaired thyroid, pituitary, or adrenal function; Malnutrition, high fever, prolonged nausea, or vomiting; Geriatric: ↑ sensitivity; dose ↓ may be required; Obstetric / Lactation: Safety not established; insulin recommended during pregnancy.

Adverse Reactions/Side Effects

Central nervous system

  • dizziness
  • drowsiness
  • headache
  • weakness


  • constipation
  • cramps
  • diarrhea
  • drug-induced hepatitis
  • heartburn
  • ↑ appetite
  • nausea
  • vomiting


  • photosensitivity (most frequent)
  • rash


  • hypoglycemia (most frequent)

Fluid and Electrolyte

  • hyponatremia


  • aplastic anemia (life-threatening)
  • agranulocytosis
  • leukopenia
  • pancytopenia
  • thrombocytopenia


Drug-Drug interaction

Ingestion of alcohol may result in disulfiram-like reaction.Effectiveness may be ↓ by concurrent use of diuretics, corticosteroids, phenothiazines, hormonal contraceptives, estrogens, thyroid preparations, phenytoin, nicotinic acid, sympathomimetics, and isoniazid.Alcohol, androgens (testosterone), chloramphenicol, clofibrate, MAO inhibitors, NSAIDs (except diclofenac), salicylates, andsulfonamides may ↑ the risk of hypoglycemia.Concurrent use with warfarin may alter the response to both agents (↑ effects of both initially, then ↓ activity; close monitoring recommended during any changes in dosage).Beta blockers may mask the signs and symptoms of hypoglycemia.Glucosamine may worsen blood glucose control.Fenugreek, chromium, and coenzyme Q-10 may produce additive hypoglycemic effects.


Oral (Adults) 1000–2000 mg/day in single or divided doses; then adjusted to maintanance dose of 250–2000 mg/day (some patients may require up to 3000 mg/day).

Availability (generic available)

Tablets: 500 mg

Nursing implications

Nursing assessment

  • Observe patient for signs and symptoms of hypoglycemic reactions (sweating, hunger, weakness, dizziness, tremor, tachycardia, anxiety). Patients on concurrent beta-blocker therapy may have very subtle signs and symptoms of hypoglycemia.
  • Assess patient for allergy to sulfonamides.
  • Monitor intake and output ratios and daily weight. Notify health care professional promptly if peripheral edema, rales/crackles, or a significant discrepancy in totals develops.
  • Lab Test Considerations: Serum glucose and hemoglobin A1C should be monitored periodically throughout therapy to evaluate effectiveness of treatment.
    • Monitor CBC periodically throughout therapy. Notify health care professional promptly if decrease in blood counts occurs.
    • May cause an increase in AST, LDH, BUN, and serum creatinine.
  • Overdose is manifested by symptoms of hypoglycemia. Mild hypoglycemia may be treated with administration of oral glucose. Severe hypoglycemia should be treated with IV D50W followed by continuous IV infusion of more dilute dextrose solution at a rate sufficient to keep serum glucose at approximately 100 mg/dL.

Potential Nursing Diagnoses

Imbalanced nutrition: more than body requirements (Indications)
Noncompliance (Patient/Family Teaching)


  • high alert: Accidental administration of oral hypoglycemic agents to non-diabetic adults and children has resulted in serious harm or death. Before administering, confirm that patient has Type 2 diabetes. Do not confuse tolbutamide with tolazamide.
  • Patients stabilized on a diabetic regimen who are exposed to stress, fever, trauma, infection, or surgery may require administration of insulin.
    • To convert from other oral hypoglycemic agents or insulin dosage of <20 units/day, change can be made without gradual dosage adjustment. Patients taking 20–40 units/day should convert gradually by receiving oral hypoglycemic agent and a 25–50% reduction in insulin dose the 1st day, with gradual insulin dosage reduction as tolerated. Patients taking >40 units/day should use a 20–50% reduction in insulin dose the 1st day, with gradual insulin dosage adjustment as tolerated. Monitor serum glucose and urine ketones at least 3 times/day during conversion.
  • Oral: May be administered once in the morning or divided into 2 doses. Administer with meals to ensure best diabetic control and minimize gastric irritation. Do not administer after last meal of the day.
    • Tablets may be crushed and taken with fluids if patient has difficulty swallowing.

Patient/Family Teaching

  • Instruct patient to take medication at same time each day. If a dose is missed, take as soon as remembered unless almost time for next dose. Do not take if unable to eat.
  • Explain to patient that this medication controls hyperglycemia but does not cure diabetes. Therapy is long-term.
  • Review signs of hypoglycemia and hyperglycemia with patient. If hypoglycemia occurs, advise patient to drink a glass of orange juice or ingest 2–3 tsp of sugar, honey, or corn syrup dissolved in water or an appropriate number of glucose tablets and notify health care professional.
  • Encourage patient to follow prescribed diet, medication, and exercise regimen to prevent hypoglycemic or hyperglycemic episodes.
  • Instruct patient in proper testing of serum glucose and urine ketones. These tests should be closely monitored during periods of stress or illness and health care professional notified if significant changes occur.
  • May occasionally cause dizziness or drowsiness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known.
  • Caution patient to avoid other medications, especially aspirin and alcohol, while on this therapy without consulting health care professional.
  • Concurrent use of alcohol may cause a disulfiram-like reaction (abdominal cramps, nausea, flushing, headaches, and hypoglycemia).
  • Caution patient to use sunscreen and protective clothing to prevent photosensitivity reactions.
  • Advise patient to inform health care professional of medication regimen prior to treatment or surgery.
  • Advise patient to notify health care professional promptly if unusual weight gain, swelling of ankles, drowsiness, shortness of breath, muscle cramps, weakness, sore throat, rash, or unusual bleeding or bruising occurs.
  • Advise patient to carry a form of sugar (sugar packets, candy) and identification at all times describing disease process and medication regimen.
  • Insulin is the recommended method of controlling blood sugar during pregnancy. Counsel female patients to use a form of contraception other than oral contraceptives and to notify health care professional promptly if pregnancy is planned or suspected.
  • Emphasize the importance of routine follow-up exams.

Evaluation/Desired Outcomes

  • Control of blood glucose levels without hypoglycemic episodes.
Drug Guide, © 2015 Farlex and Partners


A first-generation oral sulfonylurea used to reduce glucose in type 2 diabetics whose diabetes can’t be controlled by diet.
Mechanism of action Triggers release of insulin from the pancreas.
Pharmacokinetics Metabolised in liver to an active analogue; excreted via kidneys.
Adverse effects Hypoglycaemic reactions—e.g., coma, nausea, vomiting, dizziness, cholestatic jaundice, agranulocytosis, aplastic and haemolytic anaemia, hypersensitivity, skin reactions including photosensitivity, rash and itching.
Precautions Hypertension, liver and kidney disease, allergies
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
References in periodicals archive ?
From 1950 to 1995, only one oral drug was available for the treatment of type 2 diabetes: a sulfonylurea (Orinase, Diabinese).