Microneedle ocular patch: fabrication, characterization, andex-vivoevaluation using pilocarpine as model drug

Context:Enhacing the ocular bioavailability of drugs after their topical application is a challenge. Objective:The objective of the study was to design, fabricate, and investigate the effectiveness of microneedle ocular patch (MOP) in delivering the model drug, pilocarpine HCl across the corneal membrane. Methods:MOP mimicked commercially available contact lens design elements having a diameter of 14.20 mm and a sagittal height of 3.85 mm with a convex curvature. The base of this patch contained an array of 25 pyramid-shaped microneedles measuring 521 +/- 10 mu m in length. Pilocarpine loaded MOP was prepared by micromolding technique using dissolvable polyvinyl alcohol and polyvinyl pyrrolidone matrix. MOP was characterized for physical and mechanical properties using a stereomicroscope, scanning electron microscope, and texture analyzer. Results:Histological examination after MOP application on excised human cornea showed penetration of microneedles with a required insertional force of 1.04 +/- 0.17 N. Flux of pilocarpine across excised cornea was significantly (p < 0.05) greater after application of MOP (704 +/- 149 mu g/cm(2)/h) compared with solution formulation (188 +/- 24 mu g/cm(2)/h).Ex-vivopilocarpine permeation study in porcine eye globe revealed significantly (p < 0.05) greater availability in aqueous humor within 30 min of application of MOP (249 +/- 85 mu g/ml) compared with solution formulation (46 +/- 9 mu g/ml). Conclusion:MOP can be developed as a potential ophthalmic drug delivery system.