Drug information of Tolbutamide


Drug group: blood sugar

Tolbutamide is an oral antihyperglycemic agent used for the treatment of non-insulin-dependent diabetes mellitus (NIDDM).

Mechanism of effect

Sulfonylureas lower blood glucose in patients with NIDDM by directly stimulating the acute release of insulin from functioning beta cells of pancreatic islet tissue by an unknown process that involves a sulfonylurea receptor (receptor 1) on the beta cell.

Sulfonylureas inhibit the ATP-potassium channels on the beta cell membrane and potassium efflux, which results in depolarization and calcium influx, calcium-calmodulin binding, kinase activation, and release of insulin-containing granules by exocytosis, an effect similar to that of glucose.


Tolbutamide lowers blood sugar by stimulating the pancreas to secrete insulin and helping the body use insulin efficiently. The pancreas must be able to produce insulin for this drug to work.


Half-Life: 4.5-6.5 hr

Duration: 6-24 hr

Onset: 1hr

Max Effect: 5-8 hr

Time to peak, serum: 3-4 hr

Protein Bound: 80-99%

Vd: 0.15 L/kg

Metabolism: extensively, in liver to inactive metabolites by hepatic P450 enzyme CYP2C9

Metabolites: carboxytolbutamide, hydroxymethyltolbutamide (inactive)

Excretion: mainly in urine 70-80%


  • Hemodialysis: No
  • Peritoneal dialysis: No data

Drug indications

diabetes mellitus



Type 2 Diabetes

250 mg-2 g PO qDay or q8-12hr; not to exceed 3 g/day; maintenance dose >2 g/day seldom required

Divided doses may minimize gastrointestinal side effects


Safety and efficacy not established

Drug contraindications

Hypersensitivity , Diabetes ketoacidosis

Hypersensitivity, sulfa allergy Type I diabetes, diabetic ketoacidosis


Patients with hypoglycemia, when caloric intake is decreased or there is increased stress due to infection, fever, trauma, or surgery (may need to discontinue treatment)

Risk of cardiovascular mortality increases with oral hypoglycemic drug treatments compared to treatment with diet alone or diet plus insulin

Risk of sulfonylurea-induced hemolytic anemia may increase in patients iwth glucose-6-phosphate dehydrogenase deficiency

Points of recommendation

  • Be careful if you have G6PD deficiency. Anemia may happen.
  • Do not drive if your blood sugar has been low. There is a greater chance of you having a crash.
  • Check your blood sugar as you have been told by your doctor.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • This medicine may affect certain lab tests. Tell all of your health care providers and lab workers that you take tolbutamide.
  • Talk with your doctor before you drink alcohol.
  • It may be harder to control your blood sugar during times of stress like when you have a fever, an infection, an injury, or surgery. A change in level of physical activity or exercise and a change in diet may also affect your blood sugar. Talk with your doctor.
  • Follow the diet and workout plan that your doctor told you about.
  • Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using tolbutamide while you are pregnant.
  • To gain the most benefit, do not miss doses.
  • Keep taking tolbutamide as you have been told by your doctor or other health care provider, even if you feel well.
  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

Pregnancy level


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