Mannitol

Mannitol is an osmotic diuretic and belongs to the sugar alcohol (polyol) class of compounds. After intravenous administration, mannitol is hardly metabolized and is distributed mainly in the extracellular fluid, especially within the intravascular space, thereby increasing plasma osmolality. As plasma osmolality rises, water moves from tissues such as the brain and the eye into the bloodstream, thereby reducing cerebral edema, intracranial pressure, and intraocular pressure. Mannitol is freely filtered by the glomerulus but is not reabsorbed by the renal tubules. It therefore maintains high osmotic pressure within the tubular lumen, preventing water from returning to the blood and producing osmotic diuresis.