Sulphonylureas 

Members of this family: Gliclazide, Glibenclamide and Glimepiride

Background

Sulphonylureas have been used in the treatment of diabetes for approximately 70 years now. They were discovered by chance when it was noticed that individuals treated with sulphonamide antibiotics suffered from hypoglycaemia.

The mechanism by which they lower blood sugar levels was first described in 1946. A decade later, in 1956 the first sulphonylurea used in the treatment of diabetes was developed. The older class also referred to as first-generation sulphonylureas are no longer in use.

 Second generation sulphonylureas currently available in South Africa include glibenclamide, gliclazide and glimepiride.

How do they work?

Sulphonylureas lower blood sugar by stimulating the release of insulin from the β-cells of the pancreas.

There are slight differences in how the different sulphonylureas achieve their effect, and this accounts for the differences in side effects and safety profile of the different medicines in this group.

Factors to consider when choosing a sulphonylurea

Risk of Hypoglycaemia

Sulphonylureas are known to increase the risk of hypoglycaemia. A comparison of the different sulfonylureas shows that gliclazide poses the lowest risk in the group, followed by glimepiride and glibenclamide.

Glibenclamide has been associated with the highest risk for hypoglycaemia, especially in older individuals and in those with kidney problems. This has led to the medication being removed from the World Health Organisation (WHO) list of essential medicines.

Glycaemic control

Sulphonylurea have been reported to lower HbA1c by 1.5%.The use of sulfonylureas in individuals whose target HbA1c is ≤6.5% may increase their risk of hypoglycaemia to unacceptably high levels.  Caution is advised.

Effect on Weight

Sulphonylureas have been shown to cause moderate weight gain. Gliclazide Modified Release (MR) is considered an exception in this group and has been shown not to induce weight gain.

Benefits to the heart and kidney

Studies done on sulphonylureas suggest that this group of medicines offer no protective benefits to the heart but provide moderate benefit to the kidneys. Gliclazide is the recommended medication in this group for use in kidney disease.

Cost

Sulphonylureas remain the most commonly used group of medicines in the management of diabetes, especially in low-income areas due to their affordability.

Side effects

Individuals using sulphonylureas for the first time may experience abdominal discomfort, diarrhoea and constipation. The other side effects associated with the use of sulphonylurea are those that relate to hypoglycaemia.

Useful tips for Individuals on sulphonylureas.

• Take medication 30 minutes before a meal.
• If you take the medication and not eat, your risk of hypoglycaemia is higher.
• Always carry a snack ,incase you experience symptoms of hypoglycaemia.
• Check your blood sugar often. Especially before exercise and driving.
• Talk to your Doctor or Pharmacist when using antibiotics. Sulfa-antibiotics like Bactrim may cause low blood sugar.