Corneal delivery of besifloxacin using rapidly dissolving polymeric microneedles

Penetration of antibiotics into and through the cornea is a major limiting factor in the treatment of ocular infections. Several strategies are in vogue to overcome this limitation such as use of fortified drops, gels, and subconjunctival injections. Here, we present the fabrication of rapidly dissolving polymeric microneedle array to effectively deliver besifloxacin through the cornea. Microneedles were prepared using polyvinyl alcohol and polyvinyl pyrrolidone by the micromolding technique. The model fluoroquinolone antibiotic, besifloxacin, was loaded in 36 microneedles arranged in a 6 x 6 array format within a 1 cm(2) area. The average height and base width of microneedles was 961 +/- 27 and 366 +/- 16 mu m, respectively. Each microneedle array contained 103.4 +/- 8.5 mu g of besifloxacin. Cryosectioning and confocal microscopy of excised human cornea revealed that microneedles penetrated to a depth of up to 200 mu m. Microneedles were found to completely dissolve in the cornea within 5 min. Application of microneedles for 5 min significantly (p < 0.05) improved the besifloxacin deposition and permeation through the cornea compared with free besifloxacin solution. Similarly, besifloxacin-loaded microneedles showed greater antibacterial activity in Staphylococcus aureus-infected cornea in comparison to free besifloxacin solution. Taken together, rapidly dissolving microneedles can be developed to effectively deliver besifloxacin to treat bacterial infections in the cornea and eye.