Pharmacology Flashcards
Loop diuretics work at the ___________ and interfere with the operation of ____________
thick ascending limb of the loop of henle
Na/K/Cl co-transporter
Describe what the Na/K/Cl co-transporter usually does? What is the effect of loop diuretics blocking this?
Usually drives ions out of the lumen to make the medulla salty which allows reabsorption of water in the descending limb (ascending limb is impermeable to water). The pump also drives the movement of Ca2+ and Mg2+ into the interstitium.
Blockage means less water can be reabsorbed and Na+ and water are lost in the urine.
Loop diuretics are more or less powerful than thiazides?
More
They produce rapid and profound diuresis
Loop and thiazide diuretics as well as diuresis cause?
Venal dilation (mechanism not fully understood) and this occurs even before the onset of diuresis.
Examples of loop diuretics?
Furosemide and bumetanide
Clinical indications for loop diuretics?
Acute PO, CKD when acutely unwell, hepatic cirrhosis with ascites, CHF, nephrotic syndrome, add on therapy in hypertension , to reduce acute hypercalcaemia
5 side effects of loop diuretics?
Hypokalaemia Metabolic Alkalosis Hypovolaemia and hypotension Hypocalcaemia and hypomagnaesia Hyperuricaemia and predisposition to gout
How is hypokalaemia corrected in those on loop or thiazide diuretics?
Potassium supplements or concomitant use of potassium sparing diuretics
Why do you get metabolic alkalosis with use of thiazide and loop diuretics?
H+ follows excretion of potassium
Why do loop and thiazide diuretics predispose to gout?
Competition between uric acid and diuretic agent for transporter meaning less uric acid is secreted so higher levels in the blood, hyperuricaemia predisposes to gout.
Thiazide diuretics work in the _____ and block the __________ therefore ______________
distal tubule
NaCl transporter
preventing water reabsorption as Na is followed by water
Examples of thiazide diuretics?
Bendroflumethiazide/ bendrofluazide
Hydrochlorothiazide
Indications for thiazide diuretics?
Widely used in: Mild HF and hypertension
Also have some uses in severe resistant oedema (usually combined with a loop), renal stone disease and nephrogenic DI.
7 side effects of thiazide diuretics?
Hypokalaemia Metabolic Alkalosis Hypovolaemia and Hypotension Depletion of Magnesium (BUT NOT CALCIUM) Hyperuricaemia Male sexual dysfunction (in high doses) Impaired glucose tolerance (not fully understood but should be given in caution in diabetics)
Loop or thiazides cause hypocalcaemia?
Loops cause hypocalcaemia
Thiazides actually increase reabsorption of calcium
Potassium sparing diuretics work in the ______ by blocking ________
collecting duct tubule
ENAC sodium channel
Potassium sparing diuretics work _______ and are mainly used to _________
poorly as diuretics
prevent potassium loss
Examples of potassium sparing diuretics?
Amiloride and Triamterene
Major clinical indication for potassium sparing diuretics?
In conjunction with thiazides or loops to correct hypokalaemia
Side effects of potassium sparing diuretics?
On their own they cause hyperkalaemia
Examples of aldosterone antagonists?
Spironolacton and eplerone