MANNITOL

12.1 Mechanism of Action Mannitol, when administered intravenously, exerts its osmotic diuretic effect as a solute of relatively small molecular size being largely confined to the extracellular space. Mannitol hinders tubular reabsorption of water and enhances excretion of sodium and chloride by elevating the osmolarity of the glomerular filtrate. This increase in extracellular osmolarity affected by the intravenous administration of mannitol will induce the movement of intracellular water to the extracellular and vascular spaces. This action underlies the role of mannitol in reducing intracranial pressure, intracranial edema, and intraocular pressure.

Contraindications

• • 5.1 ) • Anuria. ( 4
• • 5.2 ) • Severe hypovolemia. ( 4
• • 5.4 ) • Pre-existing severe pulmonary vascular congestion or pulmonary edema. ( 4
• • 5.5 ) • Active intracranial bleeding except during craniotomy. ( 4 )