L11: Diuretics Flashcards
What are the 2 main reasons that diuretics are used?
- Fluid Retention/Oedema
2. Hypertension
List from greatest to least - where the most sodium is reabsorbed and where the least sodium is reabsorbed in the nephron?
- Proximal Tubule
- Loop of Henle
- Distal Tubules
- Collecting Duct
As you go along, Na+ reabsorption decreases
List the 5 main classes of diuretic drugs
- Carbonic Anhydrase Inhibitors
- Loop Diuretics
- Thiazide Diuretics
- Potassium-Sparing Diuretics
- Osmotic Diuretics ac
What is Acetazolamide? What is the MOA?
- carbonic anhydrase inhibitor
- inhibits carbonic anhydrase enzyme (stops production of H+)
- Na+/H+ exchanger in PCT interrupted (H+ usually excreted and Na+ reabsorbed)
Where in the nephron do carbonic anhydrase inhibitors work?
proximal convoluted tubule
Why do carbonic anhydrase inhibitors only have a weak effect/weak diuresis?
- LOH reabsorbs a large amount of excess NaCL in tubular fluid
- Na+ taken out of filtrate and back into blood
What are the 2 main uses (non-renal) of Acetazolamide?
- Chronic Glaucoma
- Prophylaxis of Acute Mountain Sickness
What is glaucoma?
- group of eye conditions that damage the optic nerve
- usually caused by high pressure in eye (e.g. excess aqueous humour)
What is another name for High-Ceiling Diuretics?
Loop Diuretics
What is the MOA of loop diuretics?
- inhibit Na+/K+/2Cl- carrier in luminal membrane
- decreased reabsorption of Na+, K+ and Cl- from the filtrate into blood
Give examples of loop diuretics
- Bumetanide
- Furosemide
What are the main 3 therapeutic uses of loop diuretics?
- Oedema
- Hypercalcaemia
- Reducing Intracranial Pressure
List the possible adverse effects of loop diuretics
- Hypokalaemia
- Hyponatraemia
- Hypocalcaemia*
- Acute Hypovolaemia
- Hyperuricaemia
- Hyperglycaemia
- Ototoxicity (worsened with aminoglycoside antibiotics)
Which class of diuretics is the most effective?
Loop Diuretics
Where in the nephron do thiazide diuretics act?
distal tubule
Give some examples of thiazide diuretics
- Chlorothiazide
- Hydrochlorothiazide
- Chlorothialidone
What is the MOA of thiazide diuretics?
- inhibit Na+/Cl- cotransporter
- stop reabsorption of both Na+ and Cl- from the tubular filtrate into the blood
List the therapeutic uses of chlorothiazide diuretics [3]
- Hypertension (long-term management)
- Congestive Heart Failure
- Hypercalciuria (Ca2+ in urine)
List the adverse/side effects of thiazide diuretics
- Potassium Depletion (Hypokalaemia)
- Hyponatraemia
- Hyperuricaemia
- Hypovolaemia
- Hypercalcaemia*
- Hyperglycaemia
- Rare Hypersensitivity Rxn
Which 2 classes of diuretics can lead to hypokalaemia (low K+ levels)?
- loop diuretics
- thiazide diuretics
Where in the nephron do potassium-sparing diuretics work?
distal tubule and collecting duct
Give examples of potassium-sparing diuretics
- Spironolactone
- Triamterene
- Amiloride
What is the MOA of spironolactone?
- synthetic aldosterone antagonist
- competes w/ aldosterone
- prevents Na+ reabsorption
- prevents K+ excretion
What are the 2 main uses of spironolactone?
- Diuretic - not efficient; used for retention of K+*
2. Secondary Hyperaldosteronism - fixes elevated levels of aldosterone
