ABSTRACT
Urea, an osmotic diuretic (1 to 1.5 g/kg as a 30% solution given by slow IV infusion over two hours) is indicated for reducing intracranial or intraocular pressure. The osmotic diuretics and related agents consist of mannitol (Osmitrol), glycerin (Glycerol, Osmoglyn), and isosorbide (Hydronol). Mannitol and urea are nonelectrolytes that are freely filterable and undergo very little or no metabolism or renal tubular resorption. When given in sufficient quantities, these drugs increase the osmolarity of plasma and the amount of both the glomerular filtrate and the renal tubular fluid. The presence of such a drug in the lumen prevents the resorption of much of the water; hence the urine volume is increased. They do not prevent the active resorption of sodium from the tubular fluid, but some additional sodium is excreted as a normal constituent of the increased volume of urine.
