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The Sulfonylureas are a group of oral anti-diabetic drugs.

As with most drugs, their discovery was one of serendipity. In 1942, Michael Janbon and colleagues found that the Sulfonamide antibiotics had the side-effect of producing hypoglycaemia in experimental animals. Sulfonylureas entered medical practice in the early 1950's.

Sulfonylureas are true hypoglycaemics (therefore dangerous at high dose) and act to block ATP-sensitive Potassium channels in beta cells of the Islets of Langerhans in the Pancreas. This mimics the effect of physiological secretagogues such as glucose and results in membrane depolarisation, calcium entry and insulin release.

Ok, this is a bit jargon-y. Basically, insulin moves sugar from your blood into your cells. If the level of sugar in your blood is high, this is a signal to the Pancreas to kick out more insulin to bring it down again. The sulfonylureas mimic this signalling effect of sugar.

These drugs are highly effective and are first-line agents in the management of Type 2 Diabetes Mellitus.

The major potential adverse affect of the Sulfonylureas is hypoglycaemia. This can result from overdose or in patients with impaired renal or hepatic drug clearance.

Other adverse effects include weight gain (common), cholestasis and agranulocytosis or aplastic anaemia. Sulfonylureas can also potentiate the action of ADH and cause fluid retention in around 5% of patients. This effect may be useful in patients with diabetes insipidus.

There are a number of agents in the sulfonylurea class, they are best split into "generations". All sulfonylureas carry the suffix "-ide".

First generation agents include Tolbutamide and Chlorpropamide.

Second generations include Glyburide (Glibenclamide), Glipizide, Gliclazide.

The newest agent is Glimepiride which is sometimes described as belonging to a third generation.

Newer agents are generally more potent and have a better side-effect profile.

British National Formulary v.54
Brunton et al. Goodman & Gilman's The Pharmacological Basis of Therapeutics 11th edition.

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