Types
Carbonic Anhydrase Inhibitor
- Acts on proximal convoluted tubule
- Inhibits the enzyme carbonic anhydrase, which is normally involved in the breakdown of carbonic acid into carbon dioxide and water
- Inhibition of carbonic anhydrase leads to a build-up of bicarbonate instead, as the alternate pathway for carbonic acid metabolism
- Because there is now too much of it, more bicarbonate is set free into the urine
- But hydrogen ions are used as currency to exchange for the resorption of sodium ions, so a diuretic effect ensues
- Examples: acetazolamide
- The name has “c” and “a” in it
Loop
- Acts on thick ascending limb of Loop Of Henle
- Blocks Na+-K+-2Cl- transporter
- This has four ions in it, just as “loop” has four letters in it, as does the word “four“
- Examples: frusemide/furosemide
Thiazide
- Acts on distal convoluted tubule
- Blocks Na+-Cl- channel, affectionately called NKCC pump
- This has two ions in it and “thiazide” starts with “t” too
- Examples: hydrochlorothiazide
Potassium-Sparing
- Acts on collecting duct
- Does not evict potassium into urine for an ungracious hypokalaemia like the others
- Examples: amiloride, spironolactone
- Amiloride
- Blocks epithelial Na+ channel, affectionately called ENaC
- Spironolactone
- Amiloride
Others
Diuresis refers to the increased production of urine. Thus, further substances exist that can exact a diuretic effect but do not work on kidneys in the ways listed above. For example, coffee can have a weak diuretic effect, while that of alcohol is stronger.
Diuretic Actions On Calcium
Loop –> Hypocalcaemia
Thiazide –> Hypercalcaemia
Triple Whammy
- Diuretic
- ACE inhibitor or ARB
- NSAID
References
- Chaudhry, S. (2017). DIURETICS AND RENAL HORMONES. [online] McMaster Pathophysiology Review. Available at: http://www.pathophys.org/diuretics/ [Accessed 12 Sep. 2017].
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