Biguanides Flashcards
What is an example of a biguanide?
Metformin
What is the mode of action of metformin?
Increase insulin sensitivity and reduce gluconeogenesis
How does metformin exert its actions?
Not fully understood
What are the routes of delivery of metformin?
PO
When should metformin be taken?
With food or after a meal
What are the indications of metformin?
- Type 2 diabetes
- Diabetes in pregnancy (pre-existing and gestational)
- PCOS (unlicensed)
Describe the use of metformin in treating Type 2 diabetes?
1st line
When should women with gestational diabetes stop using metformin?
After delivery
Why are women with PCOS sometimes prescribed metformin?
They can develop insulin resistance
When should metformin be used with caution (or avoided)?
- AKI
- Severe renal impairment
What can happen to metformin in patients with acute or chronic renal impairment?
It can accumulate and cause lactic acidosis
What is a contraindication for the use of metformin?
Metabolic acidosis (lactic acidosis and DKA)
What drugs can metformin interact with?
- IV contrast media
- ACEi
- NSAIDs
- Diuretics
- Prednisolone
- Insulin
- Sulphonylureas
How should metformin be given if contrast media is required?
Withhold 48 hours before and after
Why should metformin be withheld before and after giving IV contrast media?
Both are nephrotoxic
How does metformin interact with ACEi’s, NSAIDs and diuretics?
Can cause AKI
How can AKI be avoided when giving metformin with ACEi’s, NSAIDs and diuretics?
Monitor renal function
How does metformin interact with prednisolone?
Elevates blood glucose, thus counteracting metformin
How does metformin interact with insulin and sulphonylureas?
Increased possibility of hypoglycaemia
What are the common side effects of metformin?
- Nausea and vomiting
- Diarrhoea
- Flatulence
- Anorexia
- Taste disturbance
- Weight loss
What are the less common side effects of metformin?
- Lactic acidosis
- Reduced vitamin B12 absorption
- Hepatitis
What is the advantage of metformin causing weight loss?
It may be useful in overweight or obese patients
What patient counselling is required with metformin?
- Treatment information
- Compliance with lifestyle measures
- Take with food
- Seek medical advice if signs of acidosis occur
- Driving advice
Give a sign of acidosis
Shallow breathing
What driving advice should be given to patients on metformin?
Same as insulin
