With osmotic diuretics, things are going from higher to lower concentration. And by things we mean WATER. Osmotic diuretics are non-electrolyte particles that pull water toward them.
What protein in our liver increases colloid osmotic pressure? Albumin! That’s what keeps fluid in the blood stream. So we could give a person an osmotically active diuretic and it pulls water through it. These particles are freely filterable at the glomerulus. These particles go through the nephron, the ureter and then end up in the bladder and take water with it. These particles are pharmacologically inert meaning they don’t go to any receptors. They just float in the blood stream and have a lower incidence of side effects.
The beauty of this class of diuretics are that there are no effects on serum electrolyte balance. All other diuretics affect these things.
There can be toxicities though. Too much of a good thing. If you pull too much fluid on the blood stream, the heart is going to have to work much harder than usual and increase the cardiac workload.
Therapeutic Uses
- Maintain urine volume during shock or renal failure.
- Protect against nephrotoxic drugs.
- Glaucoma. It can pull fluid out of the eye.
- Cerebral edema: It can pull fluid out of the brain.
Osmotic Diuretic Drugs
Mannitol – inj – Mannitol has a few uses. It can be used in shock, to protect the kidneys from nephrotoxic agents and is used in cerebral edema.
Hetastarch (Hespan) – inj – Hetastarch is typically used in shock.
Albumin – inj – Albumin is also typically utilized in shock. Is this the same albumin produced by the liver? Yes, this comes from donated blood. Is it dangerous? Can it pass disease through it? No. HIV or Hepatitis cannot be contained in the Albumin as it’s just a protein.
