Systemic delivery of insulin via the ophthalmic route

Abstract

The objective of this research project is to develop an ocular insert for the systemic delivery of insulin. Insulin was delivered by a Gelfoam®-based device. All formulations were evaluated for their ability to lower blood glucose concentrations in rabbits. Device removal and flow-through methods were used to investigate the in vivo and in vitro release of the insulin device. Results indicate that the proposed ocular device with an enhancer gives a uniform blood glucose reduction for up to 10 hours. The efficacy of the proposed device can be greatly improved by treating the gelatin sponge with either 5% acetic or 1% of HCl acid solutions. The improvements include: the elimination of enhancer and an up to 5-fold reduction of the dose of insulin with comparable efficacy to that produced by the devices containing an absorption enhancer. Based upon the data from both in vivo and in vitro dissolution studies, the prolonged activity of insulin is due to the slow release of insulin from the device. Overall, the proposed Gelfoam®-based ocular device provides uniform prolonged insulin activity for up to 10 hours. The device can be manufactured in a relatively simple way and the ingredients required are inexpensive. The information provided by this project may lead to a major contribution to the treatment of diabetes as well as to ophthalmic drug delivery in general.