Preparation and Evaluation of Nano Suspension for Ocular Route of Olopatadine Hydrochloride

The present study was aimed at the preparation and evaluation of Olopatadine Hydrochloride nanosuspension for ocular delivery to enhance drug solubility, dissolution rate, and therapeutic efficacy. Olopatadine Hydrochloride, an antihistaminic agent used in the treatment of allergic conjunctivitis, exhibits limited aqueous solubility, which can affect its ocular bioavailability. To overcome this limitation, nanosuspension formulations were developed using the solvent evaporation-ultrasonication technique employing chitosan as a polymer, Poloxamer 188 as a stabilizer, and Tween 80 as a surfactant. Nine formulations (F1–F9) were prepared by varying the concentrations of polymer and stabilizer. Preformulation studies including melting point determination, solubility analysis, organoleptic evaluation, UV spectrophotometric analysis, and FTIR studies were performed. The melting point of Olopatadine Hydrochloride was found to be in the range of 239.8–240.5°C, confirming drug purity and stability. UV spectrophotometric analysis showed a maximum absorption wavelength (λmax) at 290 nm with good linearity in the concentration range of 2–20 µg/mL. FTIR analysis confirmed the compatibility of the drug with formulation excipients. The prepared nanosuspensions were characterized for particle size, polydispersity index, zeta potential, pH, viscosity, and in-vitro drug release. The pH of formulations ranged from 6.82 to 6.90, indicating suitability for ocular administration, while viscosity values ranged from 14.8 to 16.4 cP. In-vitro drug release studies demonstrated sustained drug release behavior over 12 hours. Among all formulations, F9 exhibited the highest cumulative drug release of 99.2%, followed by F5 (98.8%) and F8 (98.1%). Stability studies revealed that formulation F7 showed excellent physical stability with no visible changes, acceptable viscosity, and maximum drug content retention (99.5%), whereas F9 exhibited precipitation during storage. The study concludes that nanosuspension technology effectively enhanced the dissolution behavior of Olopatadine Hydrochloride and provided sustained drug release. Formulation F7 demonstrated superior stability characteristics, while F9 showed the highest drug release profile. These findings indicate that Olopatadine Hydrochloride nanosuspension represents a promising ocular drug delivery system for improving therapeutic performance and patient compliance.