Thiazide and related diuretics

Question 1

Where do they act?

Answer 1

Inhibit sodium reA - act on the DCT

Question 2

Main indication?

Answer 2

Hypertension, heart failure

Question 3

Onset of action and duration of action?

Answer 3

1-2 hours and last for 12-24 hours

Question 4

Examples?

Answer 4

Bendroflumethiazide, chlortalidone* and indapamide*

* = thiazide like diuretics

Question 5

When to take?

Answer 5

In the morning, to avoid diuresis at night

Question 6

Contraindications?

Answer 6

Avoid in hypokalaemia (increase risk of digoxin toxicity), hyponatraemia, hypercalcaemia and Addison’s disease - avoid in lithium - sodium depletion - increases risk of toxicity

Question 7

How to increase potassium?

Answer 7

Potassium sparing diuretics e.g. spironolactone or potassium supplements to prevent hypokalemia - could also lead to encephalopathy in hepatic failure

Question 8

Cautions?

Answer 8

Low dose, titrate up based on renal function* avoid in severe liver disease - can exacerbate diabetes, gout and lupus

Question 9

Side effects?

Answer 9

Constipation, electrolyte imbalance, postural hypotension

Question 10

Pregnancy?

Answer 10

Do not use to treat gestational hypertension