Microneedle ocular patch: fabrication, characterization, and ex-vivo evaluation 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 µm 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 µg/cm2/h) compared with solution formulation (188 ± 24 µg/cm2/h). Ex-vivo pilocarpine 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 µg/ml) compared with solution formulation (46 ± 9 µg/ml).

Conclusion

MOP can be developed as a potential ophthalmic drug delivery system.