Diuretics Flashcards
Give two examples of loop diuretics
Furosemide
Bumetanide
What is the MoA of loop diuretics?
Blocks the NA/K/2Cl transporter in the thick ascending limb of the LoH
Therefore NaCl isn’t reabsorbed
Very potent
What effects to thiazide and loop diuretics have on potassium levels?
Hypokalaemia
- Action of the Na/K pump
- Faster flow rate of filtrate in the tubule, washes away K+ and creates a concentration gradient
What other ions are affected by loop diuretics?
Ca2+ and Mg2+ can’t be absorbed
Cl- isn’t reabsorbed, so the electrical potential of the filtrate doesn’t become +ve enough to repel the ions into the blood
What is the MoA of thiazide diuretics?
Blocks the Na/Cl transporter in the DCT
Name two thiazude diuretics
Bendroflumethiazide
Indapamide
Hydrochlorthiazide
What other ion is affected by thiazide diuretics
More Ca2+ is absorbed
Due to the build up of K+ in the lumen repelling the Ca2+ into the blood
Name an ENaC inhibitor
Amiloride
Triamterene
Name an aldosterone antagonist
Spironolactone Eplerenone (when above causes gynaecomastia)
What is the MoA of potassium sparing diuretics?
Reduction of the activity of ENaC either:
Directly (ENaC inhibitors) or
Indirectly (by antagonising the effects of aldosterone on Na/K pump which reduces the effect of ENaC)
Name a carbonic anhydrase inhibitor
Acetazolamide
What is the MoA of carbonic anhydrase inhibitors?
Stops HCO3- from reacting with H+, so the HCO3- stays with Na+, so Na+ stays in the lumen
What are carbonic anhydrase inhibitors used for?
Motion sickness
Méniere’s disease
Glaucoma (rarely used)
Name an osmotic diuretic
Mannitol
State three common side effects of diuretics in general
Hypovolaemia
Hypotension
Electrolyte disturbances
State two side effects of thiazide diuretics
Gout Hyperglycaemia (insulin regime may need adjusting) Erectile dysfunction Increased LDL and TG levels Hypercalcaemia
State two side effects of loop diuretics
Ototoxicity (inhibs Na/K/2Cl in the ear => reduced potassium in the endolymph .·. ↓APs => hearing loss) Alkalosis Increased LDL and TG levels Gout Hypocalcaemia and hypomagnesaemia
State two side effects of spironolactone
Hyperkalaemia
Impotence
Painful gynaecomastia
In which condition are thiazides commonly used?
Hypertension, late in the treatment pathway
Useful for fluid loss and vasodilation effects
In which five conditions are loop diuretics commonly used?
Hypertension secondary to fluid overload Heart failure for symptomatic relief Cirrhosis for ascites and peripheral oedema Nephrotic syndrome CKD with hypertension
In which three conditions is spironlactone used?
Decompensated liver disease (first line)
Heart failure to reduce mortality
Hypertension secondary to excess aldosterone
When are osmotic diuretics used?
To reduce high intracerebral pressure
Why may furosemide struggle in:
A) Heart failure
B) Nephrotic syndrome
C) CKD
A) reduced perfusion to the kidneys therefore reduced arrival of furosemide
B) reduced albumin therefore less carrying capacity for furosemide
C) fewer nephrons, so the OATs that are needed to transport furosemide into the nephron are occupied with more important substances
Name an ADH antagonist
Tolvaptan - used to treat hyponatramia
Lithium - side effect of the drug
