Urinary

Question 1

Osmotic diuretics mechanism of action?

Answer 1

6 carbon sugar solution. Are filtered but not reabsorbed. Increase osmotic pressure in filtrate, water moves in, increasing urinary output

Question 2

Example of an osmotic diuretic

Answer 2

Mannitol
A- oral absorption poor, IV admin 
D- distributed to ecf
E- excreted unchanged on urine
SE? Fluid overload- don't use with chf of oedema

Question 3

Carbon anhydrase inhibitors mechanism of action?

Answer 3

Work in PCT
inhibits CA enzyme, blocks CO2 reabsorption, decreases H in lumen, reduced NaH exchange- blocks reabsorption of Na and HCO3.
Increases Na and HCO3 excretion- water follows

Question 4

Carbonic anhydrase inhibitor example

Answer 4

Acetazolamide
Side effect, not primarily used
Side effects- increase H+
Don’t use with liver disease

Question 5

Loop diuretics mechanism of action

Answer 5

Most common
Works on ascending loop of henle
Inhibits Na K CL cotransporters
No osmotic pressure in ECF, water stays in filtrate
Used to treat oedema

Question 6

Loop diuretic example

Answer 6

Furosemide
Very fast acting
Decrease K- hypokaleamia- bradycardia?

Question 7

Thiazides mechanism of action

Answer 7

Work on DCT
Inhibits Na CL co transporter , before aldosterone is stimulated
Increase Na CL Mg K excretion, water stays with ions in filtrate

Question 8

Thiazide example

Answer 8

Hydrochlorothiazole
Side effects less severe than loop diuretics as they are less potent due to less Na to work with
Used to treat oedema

Question 9

Potassium sparing diuretics mechanism of action

Answer 9

All others reduce K- but these don’t.

Aldosterone is inhibited (spironolactone) k stays in blood, Na and Cl stays in filtrate- water follows

Question 10

Potassium sparing diuretic example

Not spironolactone

Answer 10

Amiloride
Inhibits NaKATPase
Prevents hypokalaemia
Inhibits aldosterone activity
Na stays infiltrate to be excreted- water stays with
K stays in blood- preventing hypokaleamia

Question 11

Dealing with incontinance

Answer 11

Decrease activity of detrusor- decrease parasymp activity
Muscarinic anatgonists- propantheline

Contract internal sphincter- increase sym activity
Alpha agonist - Phenylpropanalamine

Question 12

Dealing with urine retention

Answer 12

Increase activity of detrusor- parasym activation
Muscarinic agonist- bethanecol

Relax internal sphincter- alpha antagonist- prazosin

Inhibit volunatry externla sphincter
Central? Diazepam
Peripheral? Dantrolene