Lecture 5 - Diuretics And Heart Failure Flashcards
What are diuretics?
Drugs that increase urine output
What does natriuretic mean?
Loss of Na+ in urine
What does aquaretic mean?
Loss of water without electrolytes
What medical conditions are diuretics used for?
Primary hypertension
Chronic heart failure
Nephrotic syndrome
CKD
Decompensated liver disease (not a lot of albumin made)
What are some categories of diuretics?
Carbonic anhydrase inhibitors
Osmotic diuretics
SGLT2 inhibitors
Loop diuretics
Thiazides
Potassium sparing diuretics
Aldosterone antagonists
ADH antagonists
What are some common adverse drug effects of diuretics?
Hypovolaemia and hypotension
Electrolyte disturbance
Metabolic abnormalities
Anaphylaxis (allergy)
Why can diuretics lead to acute kidney injury?
Hypovolaemia and hypotension leads to activation of RAAs
How do Thiazides and thiazide like diuretics act?
Inhibit Na+/Cl- Cotransporter in DCT
Means more Na+ and Cl- ini filtrate which helps lose lots of water due to the higher osmotic pressure in the filtrate
What are some adverse effects of thiazides and thiazide like diuretics?
Hyperuricaemia (uric acid levels inc lead to Gout)
Hyperglycaemia
Erectile dysfunction
Hypercalcaemia
Inc LDL and TG
HYPOKALAEMIA
How does use of Thiazides and thiazide like diuretics cause hypokalaemia?
Na+/Cl- inhibition
Na+ levels in filtrate higher
More Na+ taken up by ENAC in collecting duct so more K+ leaves via ROMK
What are some drug-drug interactions that shouldn’t be used at the same time as thiazides and thiazide like diuretics?
Alcohol (diuretic)
Amlodipine (Ca2+ channel blocker)`
What are 2 examples of Thiazde and Thiazide like diuretic?
Indapamide
Bendroflumethiazide
When are some contraindications to using thiazides?
Addisons disease (cortisol needed to regulate Na+, without it Na+ low, thiazides can cause hyponatraemia)
Hypercalcaemia
Hyponatraemia
Refractory hypokalaemia
Hyperuricaemia
What channel do Loop Diuretics block?
NKCC channel in the ascending limb of loop of Henle
How do loop diuretics act as a diuretic?
Block NKCC channel
Means lots of Na+ K+ and Cl- remain in the filtrate increasing the osmotic pressure
Direct dilation of capacitance veins reducing preload
When are loop diuretics given?
Acute pulmonary oedema
Fluid overload in heart failure
Nephrotic syndrome
What are the adverse effects of loop diuretics?
Dehydration
Hypotension
Hypokalaemia
Hyponatraemia
Hypocalcaemia
Hypomagnesemia
Hyperuricemia
Tinnitus (Ototoxicity)
Inc cholesterol and Triglycerides
What are some contraindications to loop diuretics?
Hypokalaemia
Hyponatraemia
Gout
Hepatic encephalopathy
What are the drug-drug interactions for loop diuretics that shouldn’t be paired?
Aminoglycosides
Digoxin
Lithium
What is an. Example of an aminoglycosides?
Gentamicin
Why can aminoglycosides (gentamicin), digoxin and lithium not be used with loop diuretics?
Aminoglycosides, digoxin and lithium are damaging to the ears (ototoxic) and loop diuretics like furosemide are also ototoxic
What are some examples of loop diuretics?
Furosemide
Bumetanide
How do Potassium sparing drugs work as diuretics?
Block ENAC channels in the collecting duct and late DCT
Reduces Na+ reabsorption in DCT
Reduces K+ excretion
What are the adverse drug effects of potasssium sparing diuretics?
Hyperkalaemia
Potential Arrythmia
What are the contraindications for potassium sparing diuretics?
Addisons disease (lack of aldosterone also prevents action of ENAC and therefore ROMK, this would worsen it)
Anuria
Hyperkalaemia
What drugs would you not give potassium sparing diuretics with?
Other K+ sparing drugs
ACEi
ARBs
What is an example of a potassium sparing diuretic?
Amiloride
What is an example of a drug that acts as a potassium sparing diuretic that’s not amiloride?
Spironolactone
What is the mechanism of action of Spironolactone?
Aldosterone receptor antagonist
Aldosterone normally upregulates ENAC to in Na+ reabsorption
So if antagonised ENAC expression is reduced so more stays in filtrate
What are the adverse effects of Spironolactone?
Gynaecomastia
Hyperkalaemia
Severe cutaneous adverese reactions (SCARs)
What are contraindications to Spironolactone?
Addisons disease
Anuria
Hyperkalaemia