NCLEX Pharmacology Cardiovascular Drugs Practice Test

Mannitol works as an osmotic diuretic to reduce cerebral edema by drawing water out of brain tissue into the bloodstream, which lowers intracranial pressure. The best indicator of its therapeutic effect is a decrease in intracranial pressure, reflecting reduced brain swelling and improved pressure dynamics. You’ll also see diuresis and higher urine osmolality as a result of the osmotic effect, but these are secondary physiological effects, not the direct therapeutic goal. A decrease in potassium or a decrease in serum osmolality would not signal the desired outcome, and in fact mannitol tends to raise serum osmolality.