What it means
Osmotic forces move water between the blood, the spaces around cells and the cells themselves. Osmotic drugs use this: an osmotic diuretic such as mannitolMAN-ih-tolAn osmotic diuretic, given by IV, that draws water out of tissues into the blood so the kidneys can remove it.Full entry draws water out of swollen brain tissue and into the urine, and osmotic laxatives such as polyethylene glycol and lactulose draw water into the bowel to soften stool.
Related terms
osmosis
The movement of water across a membrane from a less concentrated solution to a more concentrated one.
oncotic pressure
The pull that proteins in the blood, mainly albumin, exert to hold fluid inside the blood vessels.
isotonic
Having the same concentration of dissolved particles as blood, so water does not move into or out of cells.
mannitol
An osmotic diuretic, given by IV, that draws water out of tissues into the blood so the kidneys can remove it.