Metformin

Question 1

Monitoring before starting treatment

Answer 1

Renal function

Do not start if less than 30.

Question 2

Follow-up monitoring

Answer 2

Yearly renal function check in those with normal renal function.

Twice a year in those with additional risk factors (e.g. elderly) or deterioration of renal function suspected.

review dose if renal function is below 45.

Question 3

Contraindications

Answer 3

Those at risk of lactic acidosis:

Diabetic ketoacidosis

eGFR less than 30 (normal release)
Less than 45 (MR)

Risk of AKI - dehydration

Conditions that may cause tissue hypoxia - cardiac or respiratory failure (e.g. recent MI or shock)

Question 4

side effects of metformin

Answer 4

GI - nausea, vomitting, diarrhoea, abdominal pain, taste disturbance - often resolve spontaneously.

B12 deficiency

Skin reaction - erythema, pruritus (itch)

Question 5

Interaction - metformin and beta blockers

Answer 5

Beta blockers mask symptoms of hypoglycaemia e.g. tremor

Question 6

Interaction - alcohol metformin

Answer 6

Increased risk of lactic acidosis

Hypoglycaemic effect enhanced

Question 7

Interaction - topiramate, metformin

Answer 7

Plasma conc of metformin may increased by topiramate (lactic acidosis risk).

Question 7

Interaction - topiramate, metformin

Answer 7

Plasma conc of metformin may increased by topiramate (lactic acidosis risk).

Question 8

Metformin - drug class

Answer 8

Buguanide anti diabetic

Question 9

Metformin - drug class

Answer 9

Buguanide anti diabetic

Question 10

Metformin - MOA

Answer 10

Unclear - increases insulin sensitivity and glucose uptake into cells.