Drug Approvals
(British Approved Name, rINN)
Pharmacopoeias. In China, Europe, International, Japan, and US.
European Pharmacopoeia, 6th ed. (Tolbutamide). A white or almost white, crystalline powder. Practically insoluble in water soluble in alcohol and in acetone. It dissolves in dilute solutions of alkali hydroxides.
The United States Pharmacopeia 31, 2008 (Tolbutamide). A white or practically white, practically odourless, crystalline powder. Practically insoluble in water soluble in alcohol and in chloroform.
Adverse Effects, Treatment, and Precautions
As for sulfonylureas in general. Tolbutamide was implicated in the controversial reports of excess cardiovascular mortality associated with oral hypoglycaemic therapy (see under Sulfonylureas, Effects on the Cardiovascular System).
Thrombophlebitis with thrombosis has occurred after the intravenous injection of tolbutamide sodium, but this is usually painless and the vein gradually recovers. Rapid injection may cause a transient mild pain or sensation of heat in the vein.
The BNFhas suggested that tolbutamide may be suitable for use in patients with renal impairment, but that careful monitoring of blood-glucose concentration is essential. UK licensed product information recommends that it should not be used in patients with severe renal impairment.
Breast feeding. Tolbutamide is distributed into breast milk in relatively low quantities. The American Academy of Pediatricsstates that, although usually compatible with breast feeding, use of tolbutamide by breast-feeding mothers may possibly result in jaundice in the infant.
Porphyria. Tolbutamide has been associated with acute attacks of porphyria and is considered unsafe in porphyric patients.
Interactions
As for sulfonylureas in general.
Pharmacokinetics
Tolbutamide is readily absorbed from the gastrointestinal tract and is extensively bound to plasma proteins the half-life is generally within the range of 4 to 7 hours but may be considerably longer. Tolbutamide is metabolised in the liver by liydroxylation mediated by the cytochrome P450 isoenzyme CYP2C9. It is excreted in the urine chiefly as metabolites with little hypoglycaemic activity. Tolbutamide has been detected in breast milk.
Uses and Administration
Tolbutamide is a sulfonylurea antidiabetic. It is given orally in the treatment of type 2 diabetes mellitus and has a duration of action of about 10 hours.
The usual initial dose in type 2 diabetes mellitus may range from 1 to 2 g daily, given either as a single dose with breakfast or, more usually, in divided doses. Maintenance doses usually range from 0.25 to 2 g daily. Although it is unlikely that the response will be improved by increasing the dose further, daily doses of 3 g have been given.
Tolbutamide sodium (C12H17N2Na03S = 292.3) has sometimes been used in the diagnosis of insulinoma as well as other pancreatic disorders including diabetes mellitus. The equivalent of 1 g of tolbutamide is given by intravenous injection as a 5% solution usually over 2 to 3 minutes. Tolbutamide sodium 1.08 g is equivalent to about 1 g of tolbutamide.
Preparations
British Pharmacopoeia 2008: Tolbutamide Tablets
The United States Pharmacopeia 31, 2008: Tolbutamide for Injection Tolbutamide Tablets.
Proprietary Preparations
Australia: Rastinon
Czech Republic: Dirastan
Denmark: Arcosal
Germany: Orabet Hong Kong Diatol
Israel: Orsinon
Mexico: Artosin Bioglusil Dabetil Diatelan Diaval Flusan Ifumelus Rastinon
New Zealand: Diatol
Poland: Diabetol
South Africa: Tydadex
Singapore: Tolmide
USA: Orinase; Orinase Diagnostic