Diuretics

Question 1

What are diuretics?

Answer 1

A class of drugs which increases diuresis, by increasing the excretion of sodium.

Question 2

What indications are diuretics used for?

Answer 2

Oedema 
Heart failure
Liver cirrhosis 
Hypertension 
Renal disease

Question 3

List the four classification for diuretics.

Answer 3

Loop diuretics
Thiazide diuretics
Thiazide-like diuretics
Potassium spring diuretics

Question 4

Give two examples of loop diuretics.

Answer 4

Furosemide

Bumetanide

Question 5

Explain the Mechanism of action (MoA) of loop diuretics

Answer 5

Inhibits the Na/K/2Cl transporter.

Reduced the reabsorption of Na, K and Cl reabsorption in the THICK ASCENDING LIMB of loop of Henle

Question 6

PK properties of diuretics.

Answer 6

Poorly absorbed (50%) - large dose required (furosemide) 
Butemanide nearly completely absorbed (80-100%)

Absorption is impaired in severe heart failure
Usually short half life

Question 7

Interaction of Loop diuretics.

Answer 7

Furosemide reduced excretion of lithium

Furosemide + ahminoglycosides increase nephrotoxic and ototoxic effects

Question 8

Interaction of Loop diuretics.

Answer 8

Furosemide reduced excretion of lithium

Furosemide increases risk of digoxin toxicity
Furosemide + ahminoglycosides increase nephrotoxic and ototoxic effects

Question 9

What are the uses of Loop diuretics?

Answer 9

Oedema due to cardiac failure, hepatic disease
Acute pulmonary oedema
Acute/chronic renal failure

Question 10

Give examples of thiazide diuretics.

Answer 10

Bendoflumethiazide

Hydrochlorothiazide

Question 11

MoA of thiazide diuretics.

Answer 11

Inhibits NA and Cl transporter and reabsorption in the DCT

Question 12

What indications are thiazide diuretics used for?

Answer 12

Hypertension, nephrogenic diabetes insipidus

Oedema due to heart failure

Question 13

PK properties of thiazide diuretics

Answer 13

Well absorbed and excreted unchanged (kidney)
Half life = 8-12 hours
given once a day

Question 14

What are the side effects of thiazide diuretics?

Answer 14

Hypokalaemia
Dehydration
Hypercalcaemia

Question 15

Examples of thiazide-like diuretics.

Answer 15

Indapamide
Metolazone
Chlorthalidone

Question 16

Examples of potassium-sparing diuretics. (MRB - Aldosterone antagonist)

Answer 16

Spironolactone

Eplerone

Question 17

Examples of sodium channel blockers.

Answer 17

Amiloride

Triameterne

Question 18

MoA of sodium channel blockers

Answer 18

Blocks epithelial sodium channels (ENaC) in DCT
Reduces movement of sodium across the apical membrane

(Reducing Na reabsorption and K secretion)

Question 19

MoA of Mineralocorticoid receptor blockers

Answer 19

Blocks aldosterone receptors in DCT. Act through active metabolite canerone

Question 20

Indications of Potassium sparing diuretics.

Answer 20

Aldosetronism
Cirrhosis - oedema or ascites
Heart failure
Nephrotic syndrome

Question 21

What is ascites?

Answer 21

Fluid collection in the spaces within the abdomen.

Can be very painful

Question 22

Side effects of potassium sparing diuretics:?

Answer 22

Nausea and vomitting
Hyperkalaemia
Menstrual disturbances

Question 23

What do potassium sparing diuretics interact with?

Answer 23

K-sparing diuretics + ACE inhibitor or NSAID - increases the risk of hyperkalaemia

SPironolactone decreases excretion of digoxin

Question 24

PK properties of amiloride?

Answer 24

Poorly absorbed

completely absorbed by the kidneys

Question 25

PK properties of spironolactone?

Answer 25

Well absorbed short half-life converted to numerous active metabolites

Question 26

What do diuretics do in heart failure?

Answer 26

Relieve symptoms Relive circulatory congestion and pulmonary and peripheral oedema Reduce Atrial and ventricular diastolic pressure little impact on mortality

Question 27

What line of treatment is diuretics in heart failure?

Answer 27

Second line treatment