Abstract
Purpose:
The most common procedure for corneal cross-linking requires the use of an aqueous solution of Riboflavin-5-phosphate (RFP) instilled in denuded cornea. The aim of our study was the development of an aqueous new ophthalmic formulation based on a new Riboflavin complex (MDV1224) able to ensure the corneal trans-epithelial penetration of the active ingredient that would ensure a correct corneal cross-linking.
Methods:
Trans-corneal permeability of Riboflavin in MDV1224 was evaluated by using the Franz diffusion cells (excised porcine cornea) at 37°C, for 360 minutes compared to RFP. The donor chamber contained the MDV1224 or RFP. The receiver chamber contained an isotonic phosphate buffer saline solution (pH 7.4). Samples were collected from the receiver chamber every 60 min and quantitatively analyzed by high performance liquid chromatography (HPLC). The permeation parameters (e.g.: the trans-corneal permeability, cm/sec) were calculated by plotting the amounts (µg/cm2) of Riboflavin in MDV1224 or RFP permeated through the porcine corneal cells over time (minutes). Riboflavin stability in the MDV1224 was also monitored for six months in dark conditions as requested by the ICH recommendation and compared to RFP.
Results:
Trans-corneal permeability of MDV1224 (45.7x10-6cm/sec) was almost tenfold greater compared to that of RFP (4.8x10-6cm/sec). After six months, stability data at 40°C and 25°C showed high degradation values for both Riboflavin in MDV1224 and RFP formulations, while at 2-8°C Riboflavin in MDV1224 and RFP showed only 3% of degradation.
Conclusions:
The new Riboflavin complex in the MDV1224 formulation was able to increase the porcine corneal penetration by 852% vs the commercial RFP. In vivo studies are needed to confirm that the higher delivery of MDV1224 Riboflavin vs RFP is able to guarantee a correct corneal cross-linking after instillation of the MDV1224 in the intact human cornea.
Keywords: 482 cornea: epithelium •
480 cornea: basic science