hyperosmotic

Hyperosmotic describes a solution or environment that has a higher osmolarity than another reference solution or tissue. Osmolarity (or osmolality) is a measure of the concentration of solute particles in a solution, typically expressed in milliosmoles per liter (mOsm/L) or milliosmoles per kilogram (mOsm/kg). In the human body, normal plasma osmolality is about 275–295 mOsm/kg. A hyperosmotic solution thus exceeds this level and relative tissues, leading to osmotic gradients across cellular membranes.

When cells are exposed to a hyperosmotic environment, water tends to move out of the cells by osmosis, causing cell shrinkage. Conversely, hypoosmotic conditions draw water into cells, potentially causing swelling. The degree and duration of exposure, as well as the specific solutes involved, influence the physiological response and risk of injury.

Clinical and practical uses of hyperosmotic agents include reducing intracranial pressure and cerebral edema, as well as managing other forms of edema. Hypertonic saline solutions (such as 3% or higher) and osmotic diuretics like mannitol are used in acute care to draw water from swollen brain tissue into the bloodstream. These treatments require careful monitoring of electrolytes, fluid balance, and kidney function.

Hyperosmotic agents also have applications in ophthalmology to reduce corneal edema and in research contexts to study osmoregulation and cellular responses to osmotic stress. Side effects can include dehydration, electrolyte disturbances, and potential tissue injury if overused or mismanaged.