• cyclodextrins
• dexamethasone
• eyedrop
• mucoadhesion

The ocular administration of actives is still a challenge. In fact, eye drops ocular bioavailability is very low due to the small absorption surface, the dilution effect in the tear fluid and the rapid removal after blinking reflex. It has been shown that active with 2 <LogP <3 mostly have higher permeation; they tend to be administrated as suspensions because of their poor solubility in water, thus causing frequent redness and irritation. To overcome this problem, we synthetized a mucoadhesive cyclodextrin capable to form inclusion complex, able to increase the ocular residence time, the apparent solubility and the stability of lipophilic active principles.
Briefly, in this thesis work we performed synthesis and characterization of thiolated cyclodextrins able to prolonging the ocular residence time of poorly soluble active principles by exploiting covalent cyclodextrin-mucus interactions. Hydroxypropyl-β-cyclodextrin (HP-β-CD) was used for this purpose. A screening on the complexation capacity of this cyclodextrin was performed on three biopharmaceutical class IV drugs (poorly soluble and with low permeability): diacerein, ciprofloxacin and dexamethasone.