Tolbutamide (Efficacy)

Tolbutamide is an oral hypoglycaemic of the sulphonylureas group. The hypoglycaemic activity leads to a saving in the metabolism of carbohydrates. Tolbutamide is prescribed, alone or in combination with other oral antidiabetics, for the treatment of type II diabetes mellitus.

The beta-cytotropic effects in the pancreas produce an increase in insulin secretion and a reduction in the threshold of glucose sensitivity of the β-cells or an increase in their reactivity to glucose. The extrapancreatic effects, by means of a reduction of the insulin-dependence of the peripheral tissues (resistance to the insulin), produce in the target tissues an increase of the union of insulin and of the sensitivity to it.


Unstable (juvenile) type I diabetes (insulin dependent), diabetic coma; Metabolic decompensation of diabetic origin (ketoacidosis or precoma); hypoglycemic states; renal failure (serum creatinine above 2 mg/dl); hypersensitivity to tolbutamide; acute porphyria.

Do not prescribe tolbutamide during pregnancy and lactation, precaution in case the patient plans to become pregnant.

Caution is advised in case of liver dysfunction, infections, burns or severe traumas; major surgery.


Hypoglycaemic reactions may occur due to an overdose, by interaction with other medications or by dietary mistakes. Likewise, alcohol can increase or decrease the hypoglycaemic effect.


At the beginning of the treatment, vision disorders, hypoglycaemia symptoms due to excessive doses (anxiety, chills, weakness, nausea, cold and pale skin, cold sweating, tachycardia) may occur.


The hypoglycaemic effect of tolbutamide can be potentiated by: ACE inhibitors (angiotensin-converting enzyme inhibitors), anabolic agents, β-blockers, preparations based on biguanides, MAOIs, bezafibrate, chloramphenicol, clofibrate, coumarin derivatives, fenfluramine, fluoxetine, guanetidine, feniramidol, miconazole, pentoxifylline (parenteral in high doses), preparations based on phenylbutazone, phosphamides, probenecid, salicylates, sulfinpyrazone, tetracyclines, tritoqualine.

The clonidine, guanethidine and reserpine β-blockers may mask the symptoms signaling hypoglycaemia event.

Administration with the following preparations may decrease the hypoglycemic effect of tolbutamide and promote metabolic decompensation: acetazolamide, diazoxide, glucagon, corticosteroids, indomethacin, laxative abuse, nicotinates in high-doses, estrogens, progestogens, phenothiazine derivatives, phenytoin, saluretics , thyroid hormones and sympathomimetics.

In the simultaneous treatment with clonidine and reserpine both an intensification and a reduction in the action of tolbutamide have been described.

The simultaneous consumption of alcohol can cause an increase or decrease in the hypoglycaemic effect.


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