Page 112 - Pharmaceutics IV (02-06-01305)
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Isotonicity
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Ophthalmic DD: requirements
Theoretically
• An ophthalmic preparation is considered isotonic when its tonicity is
equal to that of a 0.9% sodium chloride solution (290 mOsm).
• Hypotonic ophthalmic preparations: corneal oedema
• Hypertonic ophthalmic preparations: a dehydrating effect on the
corneal epithelium
• Hypotonic and hypertonic preparations are irritating to the eye and
therefore induce reflex tearing.
• Isotonicity is preferably maintained for ophthalmic preparations.
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Salma E. EL-Habashy 109
