Which agent is used to lower intracranial pressure and acts as a diuretic by increasing urine production?

• A. Glycerin
• B. Mannitol
• C. Furosemide
• D. Acetazolamide

Answer: (B)

Osmotic diuretics used to reduce intracranial pressure work by increasing the osmolality of the blood, which pulls water out of swollen brain tissue into the bloodstream so it can be eliminated by the kidneys. Mannitol fits this role best: when given intravenously, it raises plasma osmolality and is filtered by the kidneys but not reabsorbed, so water follows into the urine, producing osmotic diuresis. This both lowers brain water content and increases urine production, directly addressing the intracranial edema that elevates pressure. Other options use different mechanisms or are less effective for rapid ICP reduction—acetazolamide lowers CSF production but isn’t an osmotic diuretic; furosemide is a loop diuretic that reduces fluid overall rather than specifically drawing water from the brain; glycerin can have osmotic effects but mannitol is the classic, most commonly used agent for this purpose.