Diuretics Flashcards Preview

3: Drugs for Clinical Medicine > Diuretics > Flashcards

Flashcards in Diuretics Deck (63)
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1
Q

What are the types of diuretics?

A
  • Loop
  • Thiazide
  • Aldosterone antagonists
  • Osmotic diuretics
  • Carbonic anhydrase inhibitors
2
Q

Give 2 examples of loop diuretics

A
  • Furosemide

- Bumetanide

3
Q

What is the mechanism of action of loop diuretics?

A

Inhibits Na/K/2Cl co-transporter in the loop of Henle

4
Q

Give an example of a thiazide diuretics

A

Bendoflumethiazide

5
Q

What is the mechanism of action of thiazide diuretics?

A

Inhibits Na/Cl co-transporter in DCT

6
Q

How long do thiazide diuretics take to have effect?

A

1-2 hours

7
Q

What is the duration of action of thiazide diuretics?

A

Up to 24 hours

8
Q

What are aldosterone antagonists also known as?

A

Potassium sparing diuretics

9
Q

Give 2 examples of aldosterone antagonists

A
  • Spironolactone

- Amiloride

10
Q

What is the mechanism of action of aldosterone antagonists?

A

Prevent reabsorption of Na in the DCT, thus causing Na and H2O excretion and K retention

11
Q

Give an example of an osmotic diuretic

A

Mannitol

12
Q

What is the mechanism of action of osmotic diuretics?

A

Causes reabsorption of H2O in the PCT and the descending limb of the loop of Henle, and opposes the action of ADH in the collecting duct

13
Q

Give an example of a carbonic anhydrase inhibitor

A

Acetazolamide

14
Q

What is the mechanism of action of carbonic anhydrase inhibitors?

A

Block carbonic anhydrase at the PCT, so bicarbonate cannot be reabsorbed and is retained in the PCT with H2O and Na

15
Q

What are the routes of delivery of diuretics?

A
  • PO
  • IV
  • Topical
16
Q

What are the indications for loop diuretics?

A
  • Acute pulmonary oedema and chronic heart failure

- Oliguric renal insufficiency

17
Q

What are the indications for thiazide/thiazide-like diuretics?

A
  • Hypertension

- Nephrogenic diabetes

18
Q

What are the indications for potassium-sparing diuretics?

A
  • Hypertension
  • Hypokalaemia
  • Ascites and oedema secondary to hepatic cirrhosis
19
Q

What are the indications for osmotic diuretics?

A
  • Cerebral oedema
  • Raised intraocular pressure
  • Treatment of cystic fibrosis
20
Q

What are the indications for carbonic anhydrase inhibitors?

A

Glaucoma

21
Q

What is the role of loop diuretics in heart failure?

A

They provide symptomatic improvement but do not reduce mortality in heart failure

22
Q

Describe the use of diuretics in the elderly?

A

Should be used with caution, and at the lowest dose possible

23
Q

Why should diuretics be used with caution in the elderly?

A

Because they are particularly susceptible to side effects

24
Q

Can diuretics be used in pregnancy?

A

Should be avoided due to risk of volume depletion

25
Q

When should loop diuretics be used with caution?

A
  • Hypovolaemia
  • Hypotension
  • Prostatic hypertrophy
  • History of diabetes or gout
26
Q

When should loop diuretics be avoided?

A
  • Anuria
  • Severe hyponatraemia
  • Severe hypokalaemia
  • Comatose or pre-comatose states associated with liver cirrhosis
27
Q

When should thiazide diuretics be used with caution?

A
  • Malnutrition
  • Renal impairment
  • Patients with history of gout or diabetes
28
Q

When should thiazide diuretics be avoided?

A
  • Addison’s disease
  • Symptomatic hyperuricaemia
  • Refractory hyponatraemia
29
Q

When should potassium-sparing diuretics be used with caution?

A

Renal impairment (avoid if severe)

30
Q

When should potassium-sparing diuretics be avoided?

A
  • Hyperkalaemia
  • Hyponatraemia
  • Anuria
  • Addison’s disease
31
Q

When should osmotic diuretics be used with caution?

A

Asthma and haemoptysis, if given by inhaled route

32
Q

When should osmotic diuretics be avoided?

A
  • Anuria
  • Acute intracranial bleeding (except in craniotomy)
  • Severe heart failure
  • Severe pulmonary oedema
33
Q

When should osmotic diuretics given by inhalation be avoided?

A
  • Impaired lung function

- Patients who are hyperresponsive to mannitol

34
Q

Who should carbonic anhydrase inhibitors be used with caution in?

A
  • Eldery
  • Diabetic
  • Patients with renal calculi
  • Those with impaired alveolar ventilation
35
Q

Who should carbonic anhydrase inhibitors be avoided in?

A
  • Adrenocortical insufficiency
  • Hypochloraemic acidosis
  • Hypokalaemia
  • Hyponatraemia
  • Chronic angle-closure glaucoma (long-term use)
36
Q

What interactions are common to loop diuretics, thiazides/thiazide-like diuretics, and potassium-sparing diuretics?

A
  • Drugs affecting RAAS system
  • Anti-hypertensive drugs
  • NSAIDs
  • Lithium
37
Q

What drugs affect the RAAS system?

A
  • ACE inhibitors
  • ARBs
  • Direct renin inhibitors
38
Q

What might happen if diuretics are given with drugs affecting the RAAS system?

A

Increased risk of hyperkalaemia

39
Q

What might happen if diuretics are given with anti-hypertensive drugs?

A

Increased hypotensive effect

40
Q

What might happen if diuretics are given with NSAIDs?

A

Increased risk of nephrotoxicity

41
Q

What might happen if diuretics are given with lithium?

A

Increased risk of lithium toxicity

42
Q

What drug should not be given with potassium-sparing diuretics?

A

K supplements

43
Q

Why should K supplements not be given with potassium-sparing diuretics?

A

Increased risk of hyperkalaemia

44
Q

What drug might mannitol interact with?

A

Ciclosporin

45
Q

What might happen if mannitol is given with ciclosporin?

A

Increased risk of nephrotoxicity

46
Q

What drugs might interact with carbonic anhydrase inhibitors?

A
  • Phenytoin

- Phenobarbital

47
Q

What might happen if carbonic anhydrase inhibitors are given with phenytoin or phenobarbital?

A

Increased risk of osteomalacia

48
Q

What drugs might interact with acetazolamide?

A
  • Aminophylline

- Amiodarone

49
Q

What might happen if acetazolamide is given with aminophylline?

A

Increases risk of hypokalaemia

50
Q

What might happen if azetazolamide is given with amiodarone?

A

Hypokalaemia induced by acetazolamide increases the risk of cardiac toxicity with amiodarone

51
Q

What monitoring is required with diuretics?

A
  • Monitor fluid and electrolyte balance and serum osmolality, and review cardiac, pulmonary, and renal function
  • Monitor serum potassium level during treatment
  • Consider measuring daily weights in patients using diuretics for relief of fluid overload
52
Q

What should you do if hyperkalaemia occurs with diuretic treatment?

A

Discontinue treatment

53
Q

What are the side effects of loop diuretics?

A
  • Hypokalaemia
  • Hyponatraemia
  • Ototoxicity
  • Hyperuricaemia
  • Acute urinary retention
54
Q

What can high doses or rapid IV administration of furosemide cause?

A

Tinnitus or deafness

55
Q

What are the side effects of thiazide/thiazide-like diuretics?

A
  • Hypokalaemia
  • Altered blood lipids
  • Postural hypotension
  • Impotence
  • May precipitate gout attacks and increase the risk of pancreatitis
56
Q

What are the side effects of potassium sparing diuretics?

A
  • GI disturbances
  • Acute renal failure
  • Hyperkalaemia
  • Hyponatraemia
  • Gynaecomastia
  • Hypogonadism
  • Menstrual irregularities in women
  • Impotence in men
57
Q

What are the side effects of inhaled osmotic diuretics?

A
  • Cough
  • Bronchospasm
  • Wheezing
  • Haematoptysis
  • Irritation and pain in throat
  • Vomiting
58
Q

What are the side effects of IV osmotic diuretics?

A
  • Electrolyte and fluid imbalance
  • Hypotension
  • Thrombophlebitis
59
Q

What are the side effects of carbonic anhydrase inhibitors?

A
  • Ataxia
  • Dizziness
  • Changes in mood and libido
  • Nausea
  • Loss of appetite
  • Taste disturbance
  • Thirst
60
Q

What counselling is required with diuretics?

A
  • Frequency and nocturia
  • Compliance with monitoring
  • Reduced dietary intake of salt
61
Q

What counselling is required regarding frequency and nocturne with diuretics?

A

Inform patient that the drug will make them pass more urine and it is advisable to take doses during the day to prevent nocturia

62
Q

What counselling is required regarding compliance with monitoring with diuretics?

A

Emphasise importance of blood tests to detect harmful electrolyte imbalances to enable treatment

63
Q

What counselling specific to potassium sparing diuretics is required?

A

The patient should take this drug with or after food, and should not take potassium supplements whilst taking this drug.
Not advisable to take NSAIDs, such as ibuprofen, when taking this medication If the patient becomes unwell with vomiting and diarrhoea, they should stop taking the drug to prevent dehydration and contact their doctor for further management