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Flashcards in Diuretics Deck (46)
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1
Q

What are the regulatory functions of the kidney?

A

Fluid balance Acid-base balance Electrolyte balance

2
Q

What are the excretory functions of the kidneys?

A

Waste products Drug elimination

3
Q

What are the endocrine functions of the kidneys?

A

RAAS Erythropoietin Prostaglandins

4
Q

What are the metabolic functions of the kidney?

A

Vitamin D Polypeptides - insulin and PTH

5
Q

What do carbonic anhydrase inhibitors do?

A

Prevent action of carbonic anhydrase in the PCT, which affects reabsorption rate of Na due to Na-H antiport

6
Q

General functions of kidneys?

A

REEM Regulatory Excretory Endocrine Metabolic

7
Q

Why are carbonic anhydrase inhibitors rarely used as a diuretic?

A

Risk of metabolic acidosis and hypokalaemia

8
Q

What are carbonic anhydrase inhibitors used for?

A

Glaucoma

9
Q

Name an osmotic diuretic

A

Mannitol

10
Q

How do osmotic diuretics work?

A

Increase the osmotic gradient systemically and in the renal tubules.

11
Q

When are osmotic diuretics used?

A

Severe cerebral or pulmonary oedema

12
Q

Why are osmotic diuretics not commonly used?

A

Can cause excessive water loss and hypernatraemia

13
Q

Name some ADH antagonists

A

Lithium

Demeclocycline

14
Q

How do ADH antagonists work?

A

Reduce the concentrating ability of collecting ducts by decreasing expression of aquaporin

15
Q

Which transporters do loop diuretics work on and where? Effect of this?

A

Na-K-2Cl in the thick ascending limb of the loop of Henle

Prevent reabsorption of Na and Cl and prevent concurrent excretion of Ca and Mg due to a more positive lumen potential from K

16
Q

Name a loop diuretic

A

Furosemide

17
Q

Adverse effects of loop diuretics?

A

Hypokalaemia due to no reabsorption by Na-K-2Cl

Bumetanide can cause myalgia

Furosemide can cause reversible ototoxicity

18
Q

Indications for loop diuretics?

A

Heart failure - also have a slight venodilatory effect

Liver failure causing fluid overload

19
Q

DDIs of loop diuretics

A

Cannot be used with aminoglycosides due to risk of ototoxicity and nephrotoxicity

Rarely with digoxin or steroids due to risk of hypokalaemia

20
Q

Which transporters do thiazide diuretics affect and where? Effect of this?

A

The Na-Cl symporter in the DCT

Have a diuretic affect whilst promoting Ca reabsorption

21
Q

ADRs of thiazide diuretics?

A

Hypokalaemia

Hypercalcaemia

Hyperuricaemia (leading to gout)

Erectile dysfunction

22
Q

Indications for thiazide diuretics?

A

Heart failure

Hypertension

Kidney stones due to calcium reabsorption

23
Q

DDIs of thiazide diuretics?

A

Digoxin or steroids due to risk of hypokalaemia

Beta-blockers due to risk of hyperglycaemia, hyperlipidaemia and hyperuricaemia

Carbamazepine due to risk of hyponatraemia

24
Q

Name some potassium sparing diuretics

A

Amiloride

Spironolactone

25
Q

How do potassium-sparing diuretics work?

A

Act on ENaC channels in the late DCT and CD - so have no effect on potassium reaborption

26
Q

DDIs of potassium-sparing diuretics?

A

ACE-inhibitors - risk of hyperkalemia

Amiloride often given alongside furosemide to balance potassium

27
Q

Why can any diuretic that decreases sodium absorption before the DCT cause hypokalaemia?

A

Less sodium is reabsorbed, so there is a decrease in circulating volume and activation of RAAS

Causes aldosterone to be expressed, increasing expression of Na-K-ATPase in basolateral membrane of principal cells, and increasing K+ channels for excretion

28
Q

Name some aldosterone antagonists

A

Spironolactone

Eplerenone

29
Q

How do aldosterone-antagonists work?

A

Inhibit action of aldosterone on mineralocorticoid recepors

Less Na-K-ATPase and ENaC synthesis

30
Q

Half-life of spironolactone?

A

Metabolised to canrenone, which has a half-life of 18-24 hours, allowing longer-term use.

31
Q

ADRs of spironolactone?

A

Hyperkalemia

Some androgenic cross-reactivity causing gynaecomastia

32
Q

Indications for spironolactone?

A

Heart failure

Hypertension

Liver failure

Hyperaldosteronism e.g. Conn’s syndrome

33
Q

How does digoxin have a diuretic effect?

A

Inhibits tubular Na-K-ATPase

34
Q

What are general ADRs of any diuretic?

A

Anaphylaxis or rash

Hypovolaemia

Hypotension (which can cause acute renal failure)

Electrolyte disturbances

Metabolic abnormalities

35
Q

What is digoxin used for?

A

AF

36
Q

What must be monitored with diuretics?

A

U&Es

37
Q

Which diuretics would you prescribe in HF? Alongside what?

A

Loop or thiazide diuretics

Alongside ACEi or beta-blockers

38
Q

What diuretics are used for hypertension?

A

Thiazide diuretics or aldosterone antagonists

39
Q

What diuretics are used for liver failure?

A

Aldosterone antagonists and loop diuretics

40
Q

What are the two main issues with prescribing drugs in renal disease?

A

Drugs may reduce kidney function by direct or indirect toxicity

Drugs at normal doses may accumulate to toxic levels of they are excreted via kidneys and renal function is impaired

41
Q

Name some potentially nephrotoxic drugs

A

ACE inhibitors

Aminoglycosides

Penicillins

Cyclosporin A

Metformin

NSAIDs

42
Q

Why is renal function in the elderly over-estimated?

A

Creatinine is dependent on body mass

Therefore start with a low dose and titrate cautiously

43
Q

What can cause diuretic resistance?

A

Incomplete treatment of primary disorder

Continuation of high Na intake

Patient non-compliance

Poor absorption

Volume depletion decreasing filtration of diuretics

Volume depletion increasing aldosterone

NSAIDs reducing renal bloodflow

44
Q

What are the effects of angiotensin and prostaglandins on renal blood flow?

A

Angiotensin constricts the efferent, increasing filtration pressure and GFR

Prostaglandin dilates the afferent, increasing GFR

45
Q

ECG changes in hyperkalaemia?

A

No P-waves

Prolonged QRS complex

Tented T waves

46
Q

Treatment of hyperkalaemia?

A

Calcium gluconate

Insulin/dextrose

Calcium resonium

Sodium bicarbonate

(Salbutamol)