Iontophoresis-aided drug delivery into the eyeball via eyelid skin

Abstract

Eyelid skin has gained attention as a drug delivery site for ophthalmic drugs as an alternative to conventional eye drops. Previously, it was found that the concentration of drugs administered via eyelid skin in the conjunctival sac is lower than with eye drop administration. In the present study, we investigated the necessity for utilizing physical approaches, such as iontophoresis (IP), to promote percutaneous absorption of pilocarpine and two fluorescent dyes delivered to the eyeball via the lower eyelid skin of hairless rats. In vitro diffusion cells were used to assess the skin permeability in order to provide key insights into the relationship between skin type and drug absorption. Moreover, in vivo skin permeation was conducted to determine drug distribution in the eyeball. Seven-fold higher permeation via eyelid skin was observed compared with that without IP, indicating the usefulness of IP application. In addition, significant differences were observed in the eyeball concentrations between treatment with or without IP at 0.5 h (p < 0.05) after administration of pilocarpine. The fluorescent dyes could be observed in the eyeball after topical administration onto eyelid skin with IP. These data suggested that a short application period of IP is effective for drug delivery into eyeballs.