Diuretics

Question 1

Carbonic anhydrase inhibitors - name, uses, mechanism

Answer 1

acetazoloamide
Used for glaucoma and mountain sickness.
Inhibits CA resulting in renal loss of NAHCO3, hypokalaemia metabolic acidosis and tolerance develops after 2-3 days. Enhanced Na+ delivery results in K+ loss in CD, Na will get reabsorbed by unregulated channels further on.

Question 2

Osmotic diuretics - name, use, mechanism

Answer 2

mannitol
To reduce high intracerebral pressure

causes water to be drawn into the lumen resulting in loss of water, reduced intracellular volume, hypernatraemia risk

Question 3

SGLT2 inhibitors - mechanism, and what are the clinical findings?

Answer 3

usually facilitates na and glucose movement into the blood, but when inhibited you have increased sodium and glucose in the lumen (increased uric acid secretion) therefore the result is glucosuria and natriuresis.
There is increased Na/Cl delivery at the macula dense causing vasoconstriction afferent arteriole and increased glomerular filtration.

decreased plasma glucose, body weight, blood pressure, plasma uric acid, and increased filtration

Question 4

loop diuretics - name, uses, mechanism

Answer 4

furosemide
oedema, nephrotic syndrome, and CKD where decreased GFR leads to salt and water retention,

They inhibit the Na/K/2Cl transporter resulting in loss of sodium and water, hypokaleamic metabolic alkalosis and increased Ca2+ loss. Later sodium channels are unregulated to reabsorb sodium as increased delivery of Na causes K+ loss in CD

Question 5

thiazide diuretics - names, mechanism, side effects

Answer 5

bendroflumethiazide, indapamide

Inhibit Na/Cl cotransporter therefore loss of na and water, hypokalaemic metabolic alkalosis, increased calcium reabsorption through TRPVS channel. Enhanced Na delivery meaning increased K loss, Na reabsorbed through unregulated channels further on.

Electrolyte disturbance and metabolic effects - increased rate, glucose, lipids and impotence

Question 6

Potassium sparing - names, mechanisms (one is an aldosterone antagonist), side effects

Answer 6

amiloride - blocks Na+ reabsorption via ENaC and prevents K+ loss

spironolactone - blocks aldosterone binding therefore decreased expression of ENaC and Na/K-ATPase in principle cells of CD.

Hyperkalaemia and gynaecomastia with sprinolactone

Question 7

ADH antagonists - names, uses, mechanisms, side effects

Answer 7

tolvaptan - no aquaporins due to ADH inhibition, works on the receptor, used to treat hyponatraemia, results in dilute urine, increased free water clearance and raising of serum sodium

lithium - also inhibits ADH by working on G protein

hypernatraemia, deranged liver function

Question 8

Aldosterone antagonist - name, uses

Answer 8

spironolactone

used in heart failure, ascites, hypertension, hyperadrenalism which would be in decompensated liver disease or nephrotic syndrome