Formulary
Tolbutamide: Indications, Dosing, Side Effects and Interactions
The sulfonylureas act mainly by augmenting insulin secretion and consequently are effective only when some residual pancreatic beta-cell activity is present;...
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Tolbutamide: Indications, Dosing, Side Effects and Interactions
The sulfonylureas act mainly by augmenting insulin secretion and consequently are effective only when some residual pancreatic beta-cell activity is present;...
Drug action
The sulfonylureas act mainly by augmenting insulin secretion and consequently are effective only when some residual pancreatic beta-cell activity is present; during long-term administration they also have an extrapancreatic action.
Indications and dose
**Type 2 diabetes mellitus**
- **Adult** (By Mouth): 0.5-1.5 g daily in divided doses, dose to be taken with or immediately after meals, alternatively 0.5-1.5 g once daily, dose to be taken with or immediately after breakfast; maximum 2 g per day.
**Type 2 diabetes mellitus for tolbutamide**
- **Child 12-17 years (specialist use only)** (By mouth): 0.5-1.5 g daily in divided doses, dose to be taken with or immediately after meals, alternatively 0.5-1.5 g once daily, dose to be taken with or immediately after breakfast; maximum 2 g per day.
Cautions
Can encourage weight gain; elderly; G6PD deficiency Cautions, further information Elderly Screening Tool of Older Persons' potentially inappropriate Prescriptions (STOPP) criteria to aid medication reviews (see Prescribing in the elderly for information): potentially inappropriate if prescribed a long-acting sulfonylurea (e.g. glibenclamide, chlorpropamide, glimepiride) in type 2 diabetes mellitus (risk of prolonged hypoglycaemia).
Contraindications
Presence of ketoacidosis Contra-indications For tolbutamide Avoid where possible in Acute porphyrias
Side effects
Common or very common Abdominal pain; diarrhoea; hypoglycaemia; nausea Uncommon Hepatic disorders; vomiting Rare or very rare Agranulocytosis; erythropenia; granulocytopenia; haemolytic anaemia; leucopenia; pancytopenia; thrombocytopenia Frequency not known Allergic dermatitis (usually in the first 6-8 weeks of therapy); constipation; photosensitivity reaction; skin reactions; visual impairment Side-effects For tolbutamide Rare or very rare Aplastic anaemia; blood disorder Frequency not known Alcohol intolerance; appetite abnormal; erythema multiforme (usually in the first 6-8 weeks of therapy); exfoliative dermatitis (usually in the first 6-8 weeks of therapy); fever (usually in the first 6-8 weeks of therapy); headache; hypersensitivity (usually in the first 6-8 weeks of therapy); paraesthesia; tinnitus; weight increased
Interactions
**Severe interactions:**
- Tolbutamide should not be co-administered with sulfafurazole or coumarins as severe hypoglycaemic reactions have occurred.
**Other interactions (2):**
- The hypoglycaemic effect of tolbutamide may be enhanced by dicoumarol, MAOI's, beta-adrenergic blocking agents, sulphonamides, phenylbutazone, chloramphenicol, cyclophosphamide and salicylates or...
- Alcohol should be avoided since it may cause a disulfiram-like reaction.
Pregnancy
The use of sulfonylureas in pregnancy should generally be avoided because of the risk of neonatal hypoglycaemia.
Breast feeding
The use of sulfonylureas in breast-feeding should be avoided because there is a theoretical possibility of hypoglycaemia in the infant.
Hepatic impairment
In general, manufacturers advise avoid in severe impairment (increased risk of hypoglycaemia).
Renal impairment
Sulfonylureas should be used with care in those with mild to moderate renal impairment, because of the hazard of hypoglycaemia. Care is required to use the lowest dose that adequately controls blood glucose. Avoid where possible in severe renal impairment. Renal impairment For tolbutamide If necessary, the short-acting drug tolbutamide can be used in renal impairment but careful monitoring of blood-glucose concentration is essential.
Medicinal forms
Suspension
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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