What are sulfonylureas and which type of DM are they indicated for

These are substances with a chemical structure similar to the sulfonamides that have a hypoglycaemic effect. Initially (1956) tolbutamide was discovered, and then chlorpropamide (1957), acetohexamide (1963) and tolazamide (1966). These were called first generation sulfonylureas. Today these substances are barely used, since the second generation sulfonylureas are now available (Table 27.1), that is, glibenclamide (1969), gliclazide (1972), glipizide (1973) and glimepiride (1994). This latter substance is characterized by some researchers as a third generation sulfonylurea. An important difference of the second generation sulfonylureas is that they are more potent than the first generation ones; also, their metabolites are generally inactive. Therefore, their hypoglycaemic action is more predictable. Their duration of action ranges from 12-24 hours, except for chlorpropamide which reaches 60 hours (its elimination half-life is 36 hours). The binding to plasma

Table 27.1. Second generation sulfonylureas that are on the market. Differences of action and dosage


Content of tablet



Excretion kidneys-faeces (%)



2.5-15 mg

1 x 1-3




80 mg

40-320 mg

1-2 x 2


Gliclazide MR

30 mg


1-2 x 1


5 mg

2.5-20 mg

1 x 2



1, 2, 3, 4mg

1-6 mg

1 x 1


albumin is non-ionic in second generation sulfonylureas, whereas it is either ionic or non-ionic in first generation ones. For this reason, the second generation sulfonylureas have a lower probability of interacting with other medicines that compete with them for the binding sites.

Their indications include Type 2 DM, provided that sufficient secretion of insulin by the patient's pancreas exists. They are not indicated for the treatment of Type 1 DM or of secondary diabetes due to pancreatectomy, haemochromatosis or chronic pancreatitis. They should not be administered in pregnancy.

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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