Page 39 - Pharmaceutics IV (02-06-01305)
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Pharmaceutical requirements Isotonicity
In practice
• Tonicity is defined as the ability of a solution (extracellular solution)
surrounding a cell (semipermeable membrane) to cause that cell to
gain or lose water by osmosis.
• Extracellular solutions can be isotonic, hypotonic or hypertonic.
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Pharmaceutical requirements Isotonicity
In practice
• Body fluids, including blood and tears, have an osmotic
pressure/osmolarity corresponding to that of a 0.9% solution of
sodium chloride (isotonic): average of 284 mOsm/kg).
• Solutions with a lower osmotic pressure than body fluids or a 0.9%
sodium chloride solution are commonly called hypotonic, whereas
solutions having a greater osmotic pressure are termed hypertonic
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Salma E. EL-Habashy
