Final answer:
Mannitol is an osmotic diuretic that increases urine output by preventing water reabsorption in the kidneys and is used clinically to reduce cerebral edema. However, it can cause toxicities such as electrolyte imbalances and dehydration, and is not suitable for patients with certain conditions.
Step-by-step explanation:
Mannitol is an osmotic diuretic that promotes water loss through osmosis. This indigestible sugar, when administered, stays in the renal tubules after filtration at the glomerulus, creating an osmotic force that prevents reabsorption of water, leading to increased urine output. The mechanism of action of mannitol involves increasing the osmolarity of the glomerular filtrate, which in turn reduces the reabsorption of water from the renal tubules.
Mannitol is most often used in clinical settings to reduce cerebral edema or brain swelling after head injury. It provides a rapid reduction in intracranial pressure by extracting water from the brain tissue and excreting it via the kidneys. Additionally, it can be used in cases of oliguric renal failure to promote urine flow and prevent the progression to anuric renal failure.
The potential toxicities of mannitol involve the risk of electrolyte imbalance, particularly hyponatremia, dehydration, and hyperosmolarity. It is contraindicated in patients with severe renal disease, congestive heart failure, and active cerebral hemorrhage due to the risk of exacerbating these conditions.