Biguanides Flashcards

1
Q

What is an example of a biguanide?

A

Metformin

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2
Q

What is the mode of action of metformin?

A

Increase insulin sensitivity and reduce gluconeogenesis

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3
Q

How does metformin exert its actions?

A

Not fully understood

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4
Q

What are the routes of delivery of metformin?

A

PO

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5
Q

When should metformin be taken?

A

With food or after a meal

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6
Q

What are the indications of metformin?

A
  • Type 2 diabetes
  • Diabetes in pregnancy (pre-existing and gestational)
  • PCOS (unlicensed)
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7
Q

Describe the use of metformin in treating Type 2 diabetes?

A

1st line

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8
Q

When should women with gestational diabetes stop using metformin?

A

After delivery

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9
Q

Why are women with PCOS sometimes prescribed metformin?

A

They can develop insulin resistance

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10
Q

When should metformin be used with caution (or avoided)?

A
  • AKI
  • Severe renal impairment
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11
Q

What can happen to metformin in patients with acute or chronic renal impairment?

A

It can accumulate and cause lactic acidosis

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12
Q

What is a contraindication for the use of metformin?

A

Metabolic acidosis (lactic acidosis and DKA)

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13
Q

What drugs can metformin interact with?

A
  • IV contrast media
  • ACEi
  • NSAIDs
  • Diuretics
  • Prednisolone
  • Insulin
  • Sulphonylureas
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14
Q

How should metformin be given if contrast media is required?

A

Withhold 48 hours before and after

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15
Q

Why should metformin be withheld before and after giving IV contrast media?

A

Both are nephrotoxic

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16
Q

How does metformin interact with ACEi’s, NSAIDs and diuretics?

A

Can cause AKI

17
Q

How can AKI be avoided when giving metformin with ACEi’s, NSAIDs and diuretics?

A

Monitor renal function

18
Q

How does metformin interact with prednisolone?

A

Elevates blood glucose, thus counteracting metformin

19
Q

How does metformin interact with insulin and sulphonylureas?

A

Increased possibility of hypoglycaemia

20
Q

What are the common side effects of metformin?

A
  • Nausea and vomiting
  • Diarrhoea
  • Flatulence
  • Anorexia
  • Taste disturbance
  • Weight loss
21
Q

What are the less common side effects of metformin?

A
  • Lactic acidosis
  • Reduced vitamin B12 absorption
  • Hepatitis
22
Q

What is the advantage of metformin causing weight loss?

A

It may be useful in overweight or obese patients

23
Q

What patient counselling is required with metformin?

A
  • Treatment information
  • Compliance with lifestyle measures
  • Take with food
  • Seek medical advice if signs of acidosis occur
  • Driving advice
24
Q

Give a sign of acidosis

A

Shallow breathing

25
Q

What driving advice should be given to patients on metformin?

A

Same as insulin