Chitosan coated PLGA nanoparticles amplify the ocular hypotensive effect of forskolin: Statistical design, characterization and in vivo studies

Enhancing the ocular hypotensive effect of forskolin (FK) by means of biodegradable chitosan (CS) coated poly lactic-co-glycolic acid (PLGA) nanoparticles (NP's). One step emulsion-sonication process was employed for the formulation of CS-PLGA NP's with optimization being carried out by employing a four factor four level Box Behnken Design. The physical and spectral characterization, drug release, permeation, confocal and ocular tolerance studies (ex-vivo &in vivo) were performed. The corneal retention was assessed by gamma scintigraphic analysis and dexamethasone induced glaucamotous rabbit's intraocular pressure (IOP) was measured by means of Schiotz tonometer. Particle size of optimized CS-PLGA NP's was found as 201.56 ± 10.92 nm with a good PDI and positive zeta potential value. Entrapment efficiency and drug loading were found to be 72.32 ± 1.12% and 28.39 ± 1.67% respectively. Spectral characterization confirmed the purity and encapsulation of the drug within polymeric system. Sustained drug release and enhanced permeation profile was observed with maximum depth penetration. Ocular tolerance studies explicated its safe use. Scintigraphy studies indicated longer retention of CS-PLGA NP's while increased effectiveness after single instillation in reducing the intraocular pressure was observed. CS-PLGA-NP's could be successfully formulated and are an excellent vehicle for FK in ocular delivery.