Diuretics Flashcards
name 3 loop diuretics
what is the most potent one?
bumetanide (most potent)
furosemide
torasemide
what loop diuretic can aggravate gout?
furosemide
name 4 thiazide diuretics
bendroflumethiazide
indapamide
chlortalidone
metolazone
what thiazide diuretic works in severe renal failure?
metolazone
what thiazide diuretic is least likely to aggravate diabetes?
indapamide
name 2 aldersterone antagonists
what one is used for ascites in liver failure?
spironolactone - used for ascities
eplerenone
name 2 potassium sparing diuretics
what one can cause blue urine in some lights?
amiloride
triamterene (blue urine)
name an osmotic diuretic and what its indications?
mannitol - used in cerebral oedema and high intracrainal pressure
name a carbonic anhydrase inhibitor and its indication
acetozolamide - used in glaucoma
what is the principle behind how diuretics work?
- they increase urine output by the kidneys
- promote diuresis by inhibiting sodium reabsorption at different parts of the nephron
how do loop diuretics work?
inhibits Na+/K+/Cl- in ascending loop of henle
whats the onset and duration of action for loop diuretics?
onset = 1 hr
duration of action = 6hrs
what condition are loop diuretics cautioned in?
benign prostatic hyperplasia
what are some symptoms you need to look out for in patients on loop diuretics (reasons to use with caution) - 3 points
- diabetes mellitus - latent diabetes may become overt, and insulin requirements in people with established diabetes may increase (reduce dose)
- hearing impairment (ototoxicity) - as a result of hypoproteinaemia from furosemide which increases risk of ototoxicity (reduce dose)
- Gout - furosemide raises uric acid levels
what electroytes are raised/decrease with loop diuretics?
hypO K+, Na+, Cl-, Mg2+, Ca2+
why are loop diuretics contraindicated/cautioned in alcoholic/liver cirrhosis?
due to already low levels of K+, Na+, Cl-, Mg2+
whats the usual dose of furosemide in HF?
How many times are diuretics given a day?
20 - 40mg OM
usually diuretics given BD in HF (last dose at lunch/early afternoon)
how do thiazide diuretics work?
inhibits Na+/Cl- transporter in distal convoluted tubule
whats the onset and duration of thiazide diuretics?
1 - 2 hour onset
12 - 24 hrs duration of action
name 3 common SE to monitor in thaizides?
- GI disturbances
- Impotence (erectile dysfunction)
- high LDL/triglycerides
in what conditions should thiazide-like diuretics be prescribed with cautions?
- diabetes - can cause hyperglycaemia
- gout - hyperuricaemia
- systemic lupus erythematosus
- severe CV disease or those treated with cardiac glycoside due to danger of hypokalaemia in these patients
whats the difference in electrolyte disturbances between loop and thiazide diuretics?
loop diuretics cause low everything where as thiazide cause low K+, Na+, Mg2+, Cl- but HIGH Ca2+
both loop and thiazide diuretics are indicated for heart failure, but what additional indication do thiazide diuretics have?
What are the differnet starting doses for each indication?
hypertension
HF = 5mg OM
HTN = 2.5mg OM
what thiazide has the longest t1/2?
what can you do if the patient dislikes frequent urination?
chlortalidone
give on alternate days
how do K+ sparing diuretics work?
promotes urination without the loss of K+ by inhibitng Na+ in the distal convoluted tubule
what class of diuretic is classed as a weaker diuretic?
potassium-sparing (often used as an adjunct to loop and thiazide)
when may potassium sparing diuretics be used?
what’s there main SE?
what interactions should you look out for?
to counteract hypokalemia
SE = hyperkalaemia
Interactions = avoid drugs causing high K+ (supplements, ACEi/ARB, aldersterone antagonist)
how do aldersterone antagonists work?
inhibits aldersterone which causes sodium reabsorption via the K+/Na+/H+ co-transporter. Less potassium and hydrogen ions are exchanged for sodium therefore less lost to the urine
what are 4 key SE of spironolactone? (inc electrolyte disturbances)
- gynaecomastia - benign breast tumours, menstural distubacnes
- hypertrichosis
- change in libido
- hypERkalaemia, hypERuraemia, hypOnatraemia
what interactions should you look out for with aldersterone antagonists?
any drugs also causing high potassium
what was the MHRA warning for aldersterone antagonists?
potentially fatal/severe hyperkalaemia. Monitorng blood electrolytes essential
how do osmotic diuretics work?
inhibis sodium and water reabsorption by increasing the osmolarity (solute conc) of blood and renal filtrate. Osmotic diuretics act on the parts of nephron that are water permeale; proximal convoluted tubule and descending loop of henle
what should you avoid thiazide diuretics in patients with renal impairment?
CrCl <30ml/min
what class of diuretic may you need to increase dose of in renal impairment?
loop
