Biguanides Flashcards
What is the most commonly used biguanide?
Metformin.
Describe the mechanism of action of the biguanides.
Decreases gluconeogenesis and increases peripheral utilization of glucose. Acts in the presence of endogenous insulin and requires residual pancreatic function.
What is gluconeogenesis?
The conversion of glycogen to glucose in the liver, facilitated by glucagon.
What are the side effects of biguanide use?
GI side effects, anorexia, taste disturbance, B12 deficiency (poor absorption).
Do the biguanides cause hypos?
No.
Describe the effect of the biguanides on weight gain.
Weight neutral.
A patient who has recently been started on metformin is suffering from GI side effects, what can be done to address these side effects?
Advise patient to take metformin with food or a meal, slow the upwards titration of the dose, switch to an MR form of metformin.
In which patients are the GI side effects of metformin most common?
In patients on very high doses e.g. 3g.
What is an unlicensed use of metformin?
Treatment of polycystic ovaries.
When is metformin use contraindicated? Why?
In renal impairment due to risk of lactic acidosis.
Concomitant use of anaesthetics and metformin can cause ketoacidosis. How should this be managed?
The metformin should be suspended on the morning of surgery and restarted when renal function returns to normal.
Concomitant use of iodinated contrast agents and metformin can cause renal failure and precipitate lactic acidosis. How should this be managed?
Suspend metformin use prior to the scan and restart after 48 hours if renal function returns to baseline.
