Diuretic Flashcards
What are diuretic drugs used for and how do they work?
Hypertension. They increase sodium excretion (naturiesis) which increases water excretion (diuresis), which lowers blood volume and therefore blood pressure. They also lower peripheral resistance.
What are 4 types of diuretic?
- loop diuretics (eg Frusemide)
- thiazide diuretics (eg hydrochlorothiazide)
- thiazide-like diuretics (eg Indapamide)
- potassium sparing diuretics (eg amiloride, spirolactone)
What other conditoins are they used for?
oedema from heart failure, nephrogenic diabetes, prevention of kidney stones
When are diuretics indicated?
For first line therapy for mild and moderate hypertension. For severe hypertention they’re combined with another drug such as potassium sparing diuretic or ACE inhibitor.
what are 3 foods high in potassium
banana
spinach
potato
dried fruit, eg prunes, raisins
What are 3 foods low in potassium
cucumber
beetroot
cheese
What is the name of a loop diuretic
Frusemide
What is the site of action of frusemide
Secreted into the lumen of the proximal convoluted tubule, acts in the thick ascending loop of henle. Inhibits the sodium/potassium/2 chloride co-transporter (NKCC) to inhibit resbsorption of sodium and chloride.
Which strength of effect does Frusemide have, and what amount of sodium is absorbed at its site of action?
A powerful effect, 25% of sodium and chloride reabsorption occurs in the thick ascending loop of henle.
What other effects does frusemide have on the nephron?
loss of potassium
decreased uric acid excretion
ca2+ and mg2+ reabsorption also inhibited
When is frusemide indicated to be used
hypertension
oedema assoc with heart or renal failure, or cirrhosis
hypercalcaemia
What are the ADR of loop diuretics such as frusemide
electrolyte disturbances
(eg hypokalaemia, hypocalcaemia, hypomagnesaemia, hyperuricaemia)
dizziness
postural hypertension
Cautions with Frusemide
Use with caution in pregnancy, gout, electrolyte disturbances, prostatic hypertrophy.
What is an example of a thiazide and thiazide-like diuretic?
hydroclorothiazide, Indapamide
How do thiazide diuretics work?
They inhibit the sodium chloride symporter on the distal convoluted tubule (proximal section), by binding to the chloride binding site, inhibiting reabsorption of sodium and chloride.
how effective are thiazide diuretics and why?
Only 5% of sodium reabsorption occurs at the distal convoluted tubule, so they are only moderately potent compared to loop diuretics.
What other effects do thiazide and TL diuretics have?
increased sodium, water, potassium, chloride, Mg excretion, decreased uric acid and calcium excretion
adverse effects of thiazide diuretics
dizziness, hypotension, electrolyte disturbances, weakness, muscle cramps
Drug interactions of thiazide diuretics?
Risk of digitoxin and lithium toxicity.
Cautions in thiazide diuretics
gout
renal disease/cirrhosis
elderly
What are the names of two potassium sparing (PS) diuretics?
Amiloride and spironolactone
How effective are PS diuretics?
limited efficacy. Used in combination iwth potassium depleting diuretics such as thiazides.
What is the mechanism of action of PS diuretics?
Work on the collecting duct, block aldosterone. Amiloride causes decreased Na+ reabsorbtion in renal collecting ducts, and decreased excretion of potassium. Spionolactone is an aldosterone antagonist, inhibits sodium reabsorp and potassium excreting properties of aldosterone.
Drug interactions
digoxin and lithium
