Page 114 - Pharmaceutics IV (02-06-01305)
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Ophthalmic DD: requirements
Why?
• to mimic lacrimal pH for greater comfort to the eye
• For formulation stability
• For drug aqueous solubility of the drug, at pH 7.4 many drugs are
insoluble in water..
• For modification of ionization state
• For maximum preservative efficacy A compromise!
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Ophthalmic DD: requirements
pH considerations:
• For maximum comfort, an ophthalmic solution should have the
same pH as the tears of 7.4.
• The eye can generally tolerate topical unbuffered ophthalmic
preparations at a pH within the range of 3.5 to 8.6 (can be
neutralized by tear buffering capacity).
• Strongly acidic or basic solutions should not be used to avoid
tissue damage and rapid drug elimination (reflex tearing).
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Salma E. EL-Habashy
