Metformin

Question 1

Describe the pharmacokinetics of metformin.

Answer 1

Well-absorbed orally. No protein-binding: high Vd.

Excreted unchanged by the kidney - not metabolised. Elimination half-life 1.5-3hrs.

Question 2

Outline some common side effects of metformin.

Answer 2

GI upset (this limits patient compliance). Lactic acidosis.

Question 3

Contrast the mechanism of action of metformin and glipizide.

Answer 3

Glipizide stimulates beta-cells of the pancreas to secrete insulin (making patients more prone to hypoglycaemia than with metformin).

Metformin acts on the liver and tissues to lower blood glucose levels - it does not rely on functioning beta-cells to work.