Diuretics Flashcards
which type of diuretics are most efficacious
loop diuretics
because LoH reabsorbs 25% na and cl
name a loop diuretic
furosemide
also bumetanide and torasemide
where do loop diuretics work and MoA
decrease sodium, potassium and chloride reabsorption in thick ascending
act on Na+ K+ 2Cl- channels
indications of loop diuretics
heart failure (acute and chronic)
renal failure (including nephrotic syndrome)
liver cirrhosis with ascites
adverse effects of loop diuretics
hyponatraemia
hypokalaemia
metabolic alkalosis (due to H+ being secreted)
fluid depletion - dehydration, hypovolaemia
incontinence
ototoxicity - damage to auditory nerve
what molecule is retained in the body when on loop diuretics and what is the potential consequence of this
uric acid
gout
name a thiazide diuretic
bendroflumethiazide (most common)
also hydrochlorothiazide
thiazide type - indapamide, chlortialidone
where do thiazide diuretics work
DCT
MoA of thiazides
inhibit Na+/Cl+ co-transport in the DCT
- this offloads a little Na+ and water which follows
also cause vasodilation
indications of thiazides
hypertension
don’t offload much fluid so not helpful in heart failure etc.
adverse effects of thiazides
hypokalaemia
hyponatraemia
hypomagnesaemia
alkalosis
hyperuricaemia -> gout
hyperglycaemia
fluid depletion, incontinence
erectile dysfunction
what type of diuretic can cause erectile dysfunction and why
thiazides
they cause vasodilation
can thiazides be used in diabetics
yes but be aware that they can cause hyperglycaemia
what type of drug is spironolactone
potassium sparing diuretic
what are the two types of potassium sparing diuretics
aldosterone receptor antagonists
sodium channel blockers
what type of drug is amiloride
sodium channel blocker potassium sparing diuretic
where do potassium sparing diuretics work
distal DCT
early collecting duct
what effect does aldosterone have in the DCT
when it binds to its receptor it stimulates the formation of the Na+/K+ exchanger in the basolateral membrane
so increases Na+ reabsorption in exchange for potassium secretion
how do aldosterone receptor antagonist potassium sparing diuretics work
blocks the action of aldosterone (aldosterone would normally increase sodium reabsorption in exchange for potassium)
this means that more sodium is excreted and potassium is retained in the body
how does amiloride work
blocks the sodium channel in the luminal membrane which means it can’t get reabsorbed and more is excreted
indications of potassium sparing diuretics
chronic heart failure
liver failure with ascites
primary hyperaldosteronism (Conn’s syndrome)
resistant hypertension
what drug would be a treatment for primary hyperaldosteonism
spiranolactone
adverse effects of potassium sparing diuretics
hyperkalaemia
spironolactone has oestrogenic effects which can cause gynaecomastia
where do osmotic diuretics work
anywhere in nephron where water is reabsorbed -
PCT
DL of LoH
medullary collecting duct
MoA of osmotic diuretics
freely filtered but not reabsorbed so this creates and osmotic drag so less water and sodium is reabsorbed in nephron
indications of osmotic diuretics
raised intracranial pressure due to cerebral oedema
raised intra-ocular pressure
name a osmotic diuretic and how it is administered
mannitol
IV
give examples of carbonic anhydrase inhibitors
acetazolamide
brinzolamide
indications of carbonic anhydrase inhibitors
glaucoma
altitude sickness
adverse effects of carbonic anhydrase inhibitors
metabolic acidosis
MoA of carbonic anhydrase inhibitors
inhibitors carbonic anhydrase in PCT
this decreases the H+ and HCO3- available for exchange with Na+
means a little less sodium is reabsorbed and urine is alkalised
