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Renal > Diuretics > Flashcards

Diuretics Flashcards

1
Q

What is the glomerular filtration barrier?

A
  • Capillaries in Bowman’s capsule
  • Endothelial cells - holes
  • Basement membrane
  • GFB has selective permeability
  • GFB damage starts to lose proteins into urine
  • Ascending LOH impermeable to water
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2
Q

Can water pass through the ascending LOH?

A

No

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3
Q

Function of diuretics

A
  • Inhibit reabsorption of sodium at different levels

- More sodium excreted = more water excreted

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4
Q

Osmotic diuretics

A
  • Glomerular capillaries highly permeable to water and electrolytes
  • Mannitol
  • Increases plasma osmolarity
  • Filtered at glomerulus and poorly reabsorbed
  • Increases osmotic pressure in glomerular filtrate
  • Decreases water reabsorption from nephron
  • Doesn’t enter brain or eye
  • Uses: forces diuretics (poison), glaucoma, cerebral oedema
  • Slow IV infusion of 5-20% solution
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5
Q

Carbohydrase inhibitors

A

Increase excretion of HCO3-

  • PCT: reabsorption of sodium, water and bicarbonate
  • Carbonic anhydrase: between water and CO2 to form carbonic acid which releases ions
  • Sodium hydrogen transports sodium inside cells and hydrogen outside
  • Sodium enters blood
  • Water follows sodium
  • Sodium remains inside tubule
  • Water remains inside lumen instead of going to blood
  • E.g. acetazolamide - suppresses H+ production and reduces Na+/H+ exchange but effect is self limiting - hydrogen ion re-formed
  • Increase excretion of HCO3-
  • Uses: glaucoma - inhibits CA in eyes to reduce formation of humour, adjunct therapy in metabolic alkalosis, prophylaxis of altitude sickness
  • Adverse effects: dizziness light headache, blurred vision, GI symptoms
  • Mannitol worsens pulmonary oedema
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6
Q

What is reabsorbed in the PCT?

A

Sodium, water and bicarbonate

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7
Q

What does carbonic anhydrase do?

A

Between water and CO2 to form carbonic acid - releases H+

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8
Q

Sodium hydrogen transporter function

A

Sodium hydrogen transports sodium inside cells and hydrogen outside

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9
Q

Which ion does water follow?

A

Sodium

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10
Q

Example of carbonic anhydrase diuretics

A

E.g. acetazolamide - suppresses H+ production and reduces Na+/H+ exchange but effect is self limiting - hydrogen ion re-formed

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11
Q

Function of thiazides

A

Act on DCT which normally absorbs sodium with chloride

Stops sodium-chloride co-transporter

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12
Q

Thiazides

A
  • Act on DCT which normally reabsorbs sodium with Cl-
  • Thiazides stop sodium - transporter
  • E.g. hydrochlorothiazide
  • Blocks sodium-chloride co-transporter = higher osmolarity of urine and decreased water reabsorption
  • Effect is self limiting: hypovolaemia → renin secretion → angiotensin formation → aldosterone secretion → limitation of thiazide effect
  • Uses: long term management, congestive HF, hypertension
  • Side effects: hypokalaemia, hypocalcaemia, hyponatraemia, hyperuricaemia, hyperglycaemia, high cholesterol
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13
Q

ACEi function

A

Inhibit production of angiotensin ii

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14
Q

How is glucose reabsorbed from tubule?

A

Reabsorbed with sodium - co-transporter

Enters blood by diffusion

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15
Q

Function of SGLT2

A

Treat diabetes by preventing glucose re-uptake

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16
Q

ACEi characteristics

A
  • Enalapril
  • Inhibits production of angiotensin ii
  • Use: hypertension, reduce oedema from HF, renal failure - antiproteinuric and protective effect
  • Side effects: headache, cough, dizziness, hyperkalaemia
17
Q

Function of K+ sparing diuretics

A
  • Act in collecting duct
  • Normally in CD sodium reabsorbed, exchanged with potassium and hydrogen
  • Activity is dependent on tubular sodium conc
  • Activity regulated by aldosterone
  • ADH acts to increase AQPs normally
  • Aldosterone increases number of sodium-potassium ATPases
    Anti-aldosteronics
    Inhibit sodium channels - potassium not eliminated but kept in blood
    Action: block epithelial sodium channel in DCT, CT and CD, in conjunction with loop and thiazide diuretics to maintain K+
18
Q

Side effects of K+ sparing diuretics

A

hyperkalaemia, GI disturbances, rashes

19
Q

K+ sparing diuretics examples

A

Triamterene and amiloride

20
Q

Aldosterone antagonist example

A

Spironolactone

21
Q

Side effects of aldosterone antagonists

A

hyperkalaemia (fatal with ACEi or angiotensin receptor antagonist), GI disturbance, menstrual disorders

22
Q

Aldosterone antagonist function

A
  • E.g. spironolactone
  • Early phase increases opening of ENaC
  • Late phase promotes DNA transcription - increases synthesis of ENaC, Na+, K+, ATPase
  • Used in conjunction with loop and thiazide diuretics, hyperaldosteronism, primary failure and secondary failure
  • Side effects: hyperkalaemia (fatal with ACEi or angiotensin receptor antagonist), GI disturbance, menstrual disorders
23
Q

What do renin-angiotensin-aldosterone blockers do

A

Decrease renal perfusion - release of renin from kidneys

  • Renin converts in angiotensin 1
  • ACE converts into angiotensin 2
  • Angiotensin 2 big effector - increases sympathetic activity, water retention, release of aldosterone, vasoconstriction, release of ADH

Renal (26 decks)

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