This document discusses two diuretic drugs: Mannitol and Spironolactone. Mannitol is an osmotic diuretic that works by not being reabsorbed and increasing the osmolality of the kidney filtrate, causing water to be excreted. It can be used to treat increased intracranial pressure. Spironolactone is an aldosterone antagonist that works in the distal convoluted tubule and collecting ducts by competitively blocking aldosterone and its stimulation of sodium reabsorption in exchange for potassium. It has uses in treating ascites, nephrotic syndrome, and primary hyperaldosteronism.

1. Diuretics
DR.IBRAHIM HASSAAN,MBCHB,MSC,EDAIC
11/06/2023

2. diuretic drugs exert their effects On nephron

4. Mannitol
MOA
> Mannitol is a sugar alcohol solution, which works as an osmotic diuretic.
> The drug is freely filtered by the glomerulus but not reabsorbed.
> It increases the osmolality of the filtrate and so water follows the drug to be excreted.
> Osmotic activity occurs mainly at proximal convoluted tubule and loop of Henle
DOSE
0.5–1 g/kg IV bolus over 20 min
EFFECTS
CVS ---Initial ↑ in circulating volume – take care in patients with CCF
CNS ----↓ ICP

5. Indicated in the treatment of raised ICP BY
Decreasing the formation of CSF.
Decreasing plasma volume and thereby encouraging water to move out of the brain,reducing
edema.
Mannitol does not cross the intact blood–brain barrier.
It is free radical scavenger and so may afford some additional neuroprotection.

6. Spironolactone
USES:
Ascites
Nephrotic syndrome
Conn’s syndrome (primary hyperaldosteronism)
MOA
◦ Acts at distal convoluted tubule and collecting
ducts
◦ Competitive antagonist of aldosterone
◦ Aldosterone stimulates reabsorbtion of Na+ in
exchange for K+
Kinetics:
ABSORPTION
Oral bioavailability > 70%
DISTRIBUTION
Protein binding 90%
METABOLISM
hepatic
EXCRETION
urine