Diuretics Flashcards
List the renal actions of carbonic anhydrase inhibitors, osmotic diuretics, loop diuretics, thiazides, and aldosterone antagonists Identify the sites of action and consequences of administering the drugs listed Describe the clinical circumstances in which diuretics might be used
What molecules act in the nephron? (6)
Carbonic anhydrase inhibitor Osmotic diuretics Loop diuretics Thiazides Aldosterone antagonists Osmotic diuretics
Where do each molecules occur in the nephron?
a) Carbonic anhydrase inhibitor
b) Osmotic diuretics
c) Loop diuretics
d) Thiazides
e) Aldosterone antagonists
f) Osmotic diuretics
Carbonic anhydrase inhibitor - PCT Osmotic diuretics - PCT Loop diuretics - Thick ascending limb Thiazides - DCT Aldosterone antagonists - DCT Osmotic diuretics - collecting duct
What are the roles of diuretics? (3)
- Interfere with ionic transport in the nephron - decrease tubular reabsorption
- Act at different sites of the nephron: natriuresis (increase in Na+ excretion) - leads to diuresis (increase urine vol.)
- Clinically useful in the treatment of hypertension associated with congestive heart failure - reduce blood pressure and oedema
What is the role of osmotic diuretics?
Alter the osmolality of the plasma due to lack of absorption and metabolism
How do osmotic diuretics work? (3)
- Freely filtered through the glomerulus and act in PCT
- Water follows the conc gradient
- Results in increased urinary output via osmosis
What is mannitol?
Osmotic diuretic - increases osmolality of tubular fluid
What are the uses of mannitol? (3)
- Reduce intracranial pressure
- Reduce intraocular pressure
- Maintain urine flow
What medical use is mannitol used for?
Head injuries - reduce volume and pressure of fluid within the brain
What is the role of carbonic anhydrase in proximal tubules?
Facilitates the exchange of H+, Na+ and H2O in the proximal tubules
What do carbonic anhydrase inhibitors do?
Block this exchange of ions - reduce H+ conc. in the renal tubules
What are carbonic anhydrase inhibitors used to treat? (4)
Glaucoma
Oedema
Epilepsy
High altitude sickness
What is an example of a carbonic anhydrase inhibitor and what does it do?
Acetazolamide
Inhibit reabsorption of bicarbonate
What is a loop diuretic and where does it act?
Prevents creation of a hypertonic interstitial in the medulla
Acts on the ascending limb of the loop of Henle
What does a loop diuretic treat?
Pulmonary oedema
What is an example of a loop diuretic and what does it do?
Furosemide
Blocks ion symporters in ascending limb
