Diuretics & Renal Pharmacology Flashcards
Name 4 uses for diuretics.
- hypertension
- heart failure
- oedema due to liver disease
- nephrotic syndrome
What are carbonic anhydrase inhibitors used for?
Diuretics, primarily used in treatment of glaucoma.
What is the MOA of carbonic anhydrase inhibitors?
Inhibits MOA of carbonic anhydrase, which is needed for conversion of H20 + CO2 -> HCO3- + H+. Promotes excretion of Na+, K+ and HCO3-, creating a diuresis.
Name 2 complications of carbonic anhydrase inhibitors.
- hypokalaemia
- metabolic acidosis
What is the MOA of osmotic diuretics?
Expands ECF, which increases blood flow to kidney and washes out corticomedullary gradient. This prevents loop of Henle from concentrating urine and inhibits reabsorption of Na+ and water.
State a complication of osmotic diuretics.
Hypernatraemia - due to proportionately higher Na+ caused by diuresis.
Name 2 loop diuretics.
Furosemide
Bumetanide
What is the MOA of loop diuretics?
Inhibit NKCC2 transporter in ascending limb of loop of Henle - leads to a natiuresis and diuresis.
Name some complications of loop diuretics.
- hypokalaemic metabolic acidosis (K+ shifts out of cells due to a low ECF [K+], causes H+ ions to enter cell and create an acidosis)
- hypocalcaemia and hypomagnesia
Out of loop, thiazide and K+ sparing diuretics, which can lead to hypokalaemia and which can lead to hyperkalaemia?
Loop and thiazide - hypokalaemia (hypokalaemic metabolic acidosis).
K+ sparing diuretic - risk of hyperkalaemia.
What is the MOA of K+ sparing diuretics?
Block ENaC in the DCT, leads to decreased Na+ and water reabsorption and a natiuresis and diuresis.
Name a K+ sparing diuretic..
Amiloride
What drug class are bendroflumethiazide and indapamide?
Thiazide diuretics.
Spironolactone has 2 drug classes, what are these?
K+ sparing diuretic
Aldosterone antagonist
What are aldosterone antagonists used for and what is their MOA?
Diuretics
Inhibit aldosterone, which reduces Na+ and water reabsorption.
What are ADH antagonists used for and what is their MOA?
Diuretics
Inhibit action of ADH, leads to a diuresis.
Name 2 non-pharmacological substances with diuretic action.
Alcohol - inhibits ADH release.
Caffeine - increases GFR and decreases Na+ reabsorption.
Name some generic ADRs of diuretics.
- hypovolaemia and hypotension - can activate RAAS or cause AKI
- electrolyte disturbance
- anaphylaxis or photosensitivity rash
What is diuretic resistance?
Failure to have any reduction in oedema despite a full dose of diuretics.
State 3 causes of diuretic resistance.
- renal failure - reduced delivery of diuretic to tubule
- heart failure - can’t get to site of action due to reduced blood flow
- nephrotic syndrome - reduced proteins therefore diuretic doesn’t have anything to bind to
Why should furosemide be given orally for heart failure?
Due to reduced CO it may not reach site of action, this could lead to diuretic resistance.
What is refractory oedema?
Peripheral oedema that doesn’t respond to combined dietary Na+ restriction diuretic treatment with a loop diuretic - need to give a bigger dose to overcome this.
Name some potentially nephrotoxic drugs.
- aminoglycosides e.g. Gentamicin, vancomycin
- acyclovir
- NSAIDs
Name some drugs that shouldn’t be given if there is impaired renal function i.e. Can become toxic.
- ACEi
- diuretics
- NSAIDs
- metformin
Why should you not give NSAIDs, ACEi or ARBs to people with renal problems?
- NSAIDs inhibit vasodilation of afferent arteriole
- ACEi/ARBs inhibit vasoconstriction of efferent arteriole
- this can cause patient to develop AKI
What is the MOA of trimethoprim?
ENaC blocker
What is calcium gluconate used for?
Used to manage hyperkalaemia - doesn’t reduce K+ but stops the heart reacting to it.
