Development of cationic nanocrystals for ocular delivery

Area of Science:

• Ophthalmology
• Nanotechnology
• Pharmaceutics

Background:

• Ophthalmic drug delivery faces challenges with low bioavailability due to rapid clearance and poor solubility.
• Nanocrystal formulations offer potential to overcome these limitations by increasing surface area and mucoadhesion.

Purpose of the Study:

• To develop and characterize cationic nanocrystal formulations of dexamethasone acetate and polymyxin B for ophthalmic application.
• To evaluate the stability, mucoadhesion, and cytotoxicity of these novel formulations.

Main Methods:

• Wet bead milling was used to produce dexamethasone acetate nanocrystals (200-250nm).
• Cationic charge was imparted using cetylpyridinium chloride (CPC) and benzalkonium chloride (BAC), with polymyxin B contributing.
• Photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), and zeta potential measurements were employed for characterization.
• In vitro mucoadhesion and cytotoxicity assays were performed.

Main Results:

• Stable cationic nanocrystal formulations with positive zeta potentials (+20 to +30mV) were successfully produced.
• Formulations demonstrated significant mucoadhesion in vitro, indicated by zeta potential reversal to -15mV.
• Physical and chemical stability were maintained for 6 months under various storage conditions.
• No in vitro cytotoxicity was observed on fibroblast cell cultures.

Conclusions:

• Cationic nanocrystal formulations offer a promising strategy for enhanced ocular drug delivery.
• These formulations have the potential for increased drug solubility, residence time, and bioavailability compared to conventional eye drops.
• The developed formulations represent a viable alternative for improved ophthalmic therapeutics.