Family doctor

DRUG NAME: metformin

USE: Oral antidiabetic agent

This medicine is known as a biguanide which is indicated for non-insulin dependent (type 2) diabetes. The mode of action works mainly by inhibiting glucose production and reducing it's absorption in the gut, hence lowering the blood sugar levels in diabetics.

Metformin is the drug of choice in overweight patients in whom strict dieting has been unsuccessful or has failed to control diabetes. Hypoglycaemia (low blood sugar levels) is not a problem with this medicine, and it has a lower incidence of weight gain compared with other oral antidiabetic agents (e.g. sulphonylureas).

Caution:

• Liver and kidney impairment
• Predisposition to lactic acidosis
• Heart failure
• Dehydration (maintain adequate fluid intake)
• Alcoholics (restrict alcohol consumption)
• Recent infection, trauma or surgery
• Pregnancy and breastfeeding

Side effects:

Occasional: stomach upset (nausea, diarrhoea), weight loss, decreased vitamin B12 absorption.

Rarely: lactic acidosis (marked stomach upset/pain, loss of appetite, hyperventilation). Seek urgent medical help.

Interactions:

Significant interactions occur with warfarin (enhances anticoagulant effect) and alcohol (there is an increased risk of lactic acidosis). Cimetidine can also cause hypoglycaemia due to impaired excretion of metformin.

Patient information:

• Follow the instructions on the label of this medicine or as directed by your doctor.
• Patient should be informed about diet, exercise and blood glucose monitoring.
• Food: Taken after meals
• Alcohol: Avoid (increased risk of lactic acidosis)
• Contact doctor or seek urgent medical help if side effects are severe or ongoing.