Mannitol is a fast acting osmotic diuretic that may be used in the treatment of cerebral oedema. It reduces intracranial ressure by establishing an osmotic gradient between the plasma and the brain tissue. The effects persist for 4 to 6 hours. It is usually administered IV as a 20% solution.
Mannitol should be used as an emergency treatment or to 'buy' time prior to surgery for a mass lesion. Repeated infusions may cause equilibration and a high intracellular osmotic pressure, so counteracting further treatment. Additionally, it may precipitate lethal rises in arterial blood pressure and acute tubular necrosis.
Also, mannitol may be used in the treatment of haemochromogenuria.
It is contraindicated in congestive heart failure and pulmonary oedema.