Page 130 - Pharmaceutics IV (02-06-01305)
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Ophthalmic DD: dosage forms
Liquid preparations
Suspensions
• Formulation concept:
For formulation of drugs which are unstable or sparingly soluble in
water (steroids, …) or to prolong drug release.
• Advantages:
Particles tend to be retained in the ocular cul-de-sac and slowly
dissolving thus increasing the contact time (drug reservoir).
253
Ophthalmic DD: dosage forms
Liquid preparations
Suspensions
• Limitations:
➢ Conversions in crystal structure of the drug (polymorphic changes)
during storage, which can lead to changes in drug solubility and
dissolution
➢ Crystal growth and increase in particle size during storage
➢ Cake formation that is hard to redisperse (viscosity-imparting
agents!)
254
Salma E. EL-Habashy 127
