Diuretics Flashcards
What are diuretics?
A class of drugs which increases diuresis, by increasing the excretion of sodium.
What indications are diuretics used for?
Oedema Heart failure Liver cirrhosis Hypertension Renal disease
List the four classification for diuretics.
Loop diuretics
Thiazide diuretics
Thiazide-like diuretics
Potassium spring diuretics
Give two examples of loop diuretics.
Furosemide
Bumetanide
Explain the Mechanism of action (MoA) of loop diuretics
Inhibits the Na/K/2Cl transporter.
Reduced the reabsorption of Na, K and Cl reabsorption in the THICK ASCENDING LIMB of loop of Henle
PK properties of diuretics.
Poorly absorbed (50%) - large dose required (furosemide) Butemanide nearly completely absorbed (80-100%)
Absorption is impaired in severe heart failure
Usually short half life
Interaction of Loop diuretics.
Furosemide reduced excretion of lithium
Furosemide + ahminoglycosides increase nephrotoxic and ototoxic effects
Interaction of Loop diuretics.
Furosemide reduced excretion of lithium
Furosemide increases risk of digoxin toxicity
Furosemide + ahminoglycosides increase nephrotoxic and ototoxic effects
What are the uses of Loop diuretics?
Oedema due to cardiac failure, hepatic disease
Acute pulmonary oedema
Acute/chronic renal failure
Give examples of thiazide diuretics.
Bendoflumethiazide
Hydrochlorothiazide
MoA of thiazide diuretics.
Inhibits NA and Cl transporter and reabsorption in the DCT
What indications are thiazide diuretics used for?
Hypertension, nephrogenic diabetes insipidus
Oedema due to heart failure
PK properties of thiazide diuretics
Well absorbed and excreted unchanged (kidney)
Half life = 8-12 hours
given once a day
What are the side effects of thiazide diuretics?
Hypokalaemia
Dehydration
Hypercalcaemia
Examples of thiazide-like diuretics.
Indapamide
Metolazone
Chlorthalidone
Examples of potassium-sparing diuretics. (MRB - Aldosterone antagonist)
Spironolactone
Eplerone
Examples of sodium channel blockers.
Amiloride
Triameterne
MoA of sodium channel blockers
Blocks epithelial sodium channels (ENaC) in DCT
Reduces movement of sodium across the apical membrane
(Reducing Na reabsorption and K secretion)
MoA of Mineralocorticoid receptor blockers
Blocks aldosterone receptors in DCT. Act through active metabolite canerone
Indications of Potassium sparing diuretics.
Aldosetronism
Cirrhosis - oedema or ascites
Heart failure
Nephrotic syndrome
What is ascites?
Fluid collection in the spaces within the abdomen.
Can be very painful
Side effects of potassium sparing diuretics:?
Nausea and vomitting
Hyperkalaemia
Menstrual disturbances
What do potassium sparing diuretics interact with?
K-sparing diuretics + ACE inhibitor or NSAID - increases the risk of hyperkalaemia
SPironolactone decreases excretion of digoxin
PK properties of amiloride?
Poorly absorbed
completely absorbed by the kidneys
PK properties of spironolactone?
Well absorbed
short half-life
converted to numerous active metabolites
What do diuretics do in heart failure?
Relieve symptoms
Relive circulatory congestion and pulmonary and peripheral oedema
Reduce Atrial and ventricular diastolic pressure
little impact on mortality
What line of treatment is diuretics in heart failure?
Second line treatment
