In the present study, cyclosporine A (CsA) was successfully incorporated into cationic chitosan nanoparticles by spray-drying method aiming ocular application. Physicochemical characterisation of particles was performed in detail. Among the particles prepared using three types of chitosan with different molecular weights, particles containing chitosan with medium molecular weight was selected for in vivo studies. Selection was dependent on higher incorporation and encapsulation efficiencies of CsA and also better release characteristic in simulated tear fluid. Sheep were used in in vivo studies. Biological samples were collected at predetermined time intervals and were analysed by enzyme immune assay. CsA could be detected in both aqueous and vitreous humour samples for the duration of 72 h. In vivo release profiles indicated prolonged release of active agent from positively charged chitosan formulations. This may be attributed to enhanced residence time at the corneal and conjunctival surfaces.

Ocular allergy is one of the most common disorders of the eye surface. Following diagnosis this condition is typically treated with preparations containing antihistamines. However, anatomy of the eye and its natural protective mechanisms create challenges for ocular drug delivery. Rapid elimination of antihistamine substances due to short residency times following application can lead to insufficient treatment of ocular allergies. With this in mind, the aim of this study was to prepare a controlled ocular delivery system to extend the retention time of olopatadine hydrochloride (OLO) and in doing so to reduce the need for frequent application. We developed extended-release ocular in situ gelling systems for which in vivo retention times were determined in sheep following in vitro characterization and cytotoxicity studies. In vivo results were then compared to commercially available Patanol eye drops. the transparent gels formulated using appropriate amounts of polymers and having longer ocular retention times appear to be a viable alternative to commercially available eye drops.

A new, simple, rapid, precise, accurate and specific stability indicating reverse phase UPLC method developed for the determination of encapsulated olopatadine hydrochloride (OLO) in the polymeric nanoparticle formulations. Studies were carried out on a 2.1x50 mm, 1.8 µm Zorbax Eclipse Plus C 18 column with an optimized mobile phase of methanol, water and sodium acetate buffer solution (40:50:10, v/v/v) at a flow rate of 0.5 mL/min. OLO was detected and quantitated using a photodiode array detector at a wavelength of 246 nm and the column temperature was adjusted to 40 °C. The proposed method validation was carried out for specificity, linearity, accuracy, precision, limit of detection, limit of quantitation and robustness according to the ICH harmonised tripartite guideline "validation of analytical procedures Q2(R1)". Analytical curve was linear over the concentration range of 5-50 µg/mL. All the validation parameters were within the acceptance range. LOD and LOQ for OLO were 0.7652 and 2.3188 µg/mL, respectively. The developed method fulfilled the requirements for reliability and feasibility for the quantitative analysis of OLO in polymeric nanoparticles.