Hypertonic saline and mannitol are the main osmotic agents in use, while loop diuretics can aid in the removal of the excess fluid pulled out of the brain. Hypertonic saline is a highly concentrated solution of sodium chloride in water and is administered intravenously. It has a rapid-onset, with reduction of pressures within 5 minutes of infusion, lasting up to 12 hours in some cases, and with negligible rebound pressure. The exact volume and concentration of the hypertonic saline varies between clinical studies. Bolus doses, particularly at higher concentrations, for example 23.4%, are effective at reducing ICP and improving cerebral perfusion pressure. In traumatic brain injuries, a responsiveness to hypertonic saline lasting greater than 2 hours was associated with decreased chance of death and improved neurologic outcomes. The effects of hypertonic saline can be prolonged with combination to agents such as dextran or hydroxyethyl starch, although their use is currently controversial. When compared to mannitol, hypertonic saline has been shown to be as effective as mannitol in decreased ICP in neurocritical care and is more effective in many cases. Hypertonic saline may be preferable to mannitol in persons with hypovolemia or hyponatremia. Mannitol is an alcohol derivative of simple sugar mannose, and is historically the most commonly used osmotic diuretic. Mannitol acts as an inert solute in the blood, decreasing ICP through osmosis as discussed above. Additionally, mannitol decreases ICP and increased cerebral perfusion pressure by increasing reabsorption of cerebrospinal fluid, dilutes and decreased the viscosity of the blood, and can cause cerebral vasoconstriction.
Nevertheless, the drug is known to produce loss of memory following exposure and sleepiness, similar to the effect of benzodiazepines or alcohol poisoning. Research
Scopolamine is used as a research tool to study memory encoding. Initially, in human trials, relatively low doses of the muscarinic receptor antagonist scopolamine were found to induce temporary cognitive defects. Since then, scopolamine has become a standard drug for experimentally inducing cognitive defects in animals. Results in primates suggest that acetylcholine is involved in the encoding of new information into long-term memory.Scopolamine produces detrimental effects on short-term memory, memory acquisition, learning, visual recognition memory, visuospatial praxis, visuospatial memory, visuoperceptual function, verbal recall, and psychomotor speed. It does not seem to impair recognition and memory retrieval, though. Acetylcholine projections in hippocampal neurons, which are vital in mediating long-term potentiation, are inhibited by scopolamine. Scopolamine also inhibits cholinergic-mediated glutamate release in hippocampal neurons, which assist in depolarization, potentiation of action potential, and synaptic suppression. Scopolamines effects on acetylcholine and glutamate release in the hippocampus favor retrieval-dominant cognitive functioning. Scopolamine has been used to model the defects in cholinergic function for models of Alzheimers, dementia, fragile X syndrome, and Down syndrome.Scopolamine has also been investigated as a rapid-onset antidepressant, with a number of small studies finding positive results.NASA agreed to develop a nasal administration method. With a precise dosage, the NASA spray formulation has been shown to work faster and more reliably than the oral form to treat motion sickness. References
External links
 Media related to Scopolamine at Wikimedia Commons
"Scopolamine". Drug Information Portal.