A Novel Riboflavin Formulation for Corneal Delivery Without Damaging Epithelial Cells

PURPOSE: This study aimed to evaluate the trans-epithelial permeability enhancement and cell damage caused by a novel riboflavin composition for corneal delivery. METHODS: We developed a trans-epithelial formulation of riboflavin for corneal delivery using 1,2-dioleoyl-3-dimethylammonium-propane (DODAP) and isostearic acid (ISA). The permeation enhancement was evaluated using an in vitro corneal epithelial cell culture system by measuring the amount of transferred riboflavin with high-performance liquid chromatography. Riboflavin permeation of MedioCROSS TE, a commercially available riboflavin formulation containing benzalkonium chloride, was also evaluated and compared to that of the DODAP/ISA formulation by changing the riboflavin concentration. The trans-epithelial electrical resistance (TEER) was measured after exposure to the samples in an in vitro corneal epithelial cell culture system to assess cytotoxicity. RESULTS: The DODAP/ISA formulation demonstrated greater permeation when used together than when each component was used individually. The permeation enhancement effect of the DODAP/ISA formulation was almost the same as that of MedioCROSS TE. However, when a 10-fold higher riboflavin concentration was used in the DODAP/ISA formulation, the permeation enhancement effect surpassed that of MedioCROSS TE. After 24 hours of exposure, the TEER of the DODAP/ISA formulation was higher than that of MedioCROSS TE, indicating that the DODAP/ISA formulation was less cytotoxic than MedioCROSS TE. CONCLUSIONS: This study indicated that the DODAP/ISA formulation could serve as a less cytotoxic alternative to MedioCROSS TE. Further studies are required to determine the clinical efficacy and safety of the DODAP/ISA formulation in vivo. TRANSLATIONAL RELEVANCE: This study may provide alternative procedures for corneal collagen crosslinking with less of a cytotoxic effect on corneal epithelial cells.