Abstract
Purpose :
Delivery of biomolecules to treat ocular surface disease is rare due to the negative impact of ocular surface clearance. An extended release system would expand treatment options in ophthalmology. This study compared the ex-vivo delivery of Insulin from PROLOC® gel vs solution using a dynamic corneal diffusion model.
Methods :
The formulations consisted of either 0.25% Insulin in PBS or 0.22% Insulin in PROLOC® gel. Fresh, mature rabbit corneas or dialysis membranes were placed on spherical Franz Diffusion Cells. Solution cleared from the pre-corneal layer was analyzed via HPLC to evaluate drug retention and release profile of each formulation
Results :
The insulin solution formulation delivered a large amount of insulin that was quickly cleared from the ocular surface while the PROLOC® gel formulation delivered insulin at a sustained rate throughout the 5-hour study. No insulin diffused across the membranes. Recovery of insulin was 30-40% higher from the synthetic membrane runs compared to fresh cornea runs, see Figure 1.
The PROLOC® formulation reduced the total amount of insulin cleared from the ocular surface compared to the solution formulation. PROLOC® gel was visible at the end of the study. Analysis confirmed insulin was still present in the gel on the cornea after 5 hours. No insulin remained in the cells dosed with solution.
Conclusions :
The PROLOC® gel formulation continued to deliver drug at a steady rate throughout the 5-hour period studied while the solution formulation was rapidly removed from the ocular surface. Notably, some of the PROLOC® gel, which still contained insulin, was retained on the membrane surface until the end of the 5-hour study. Therefore, the partially depleted gel may be able to deliver drug for more than 5 hours.
The lower recovery of insulin from the cornea compared to the synthetic membrane is indicative of protein/tissue interaction.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.