A semi-solid drug delivery system for epidermal growth factor in corneal epithelial wound healing

Purpose. To investigate the effects of EGF delivered from a semi-solid drug delivery system on corneal epithelial wound healing following anterior keratectomy in rabbits. Methods. Delivery of EGF in carbopol gel was investigated. Following a 7.5 mm circular anterior keratectomy, 50 μL of either a placebo gel or an EGF gel was instilled in the inferior fornix. The gel remained in the eye for 8 hours at which time it was removed. Wound healing was evaluated by quantitative morphometry. A variety of EGF concentrations in the gel were evaluated. Tear EGF concentrations and histology of the healing corneas were also examined. Results. The enhancement factor (ratio of the healing rate with the EGF gel and control gel) was 1.13±0.12, 1.40±0.14, 1.29± 0.12, 1.80±0.22, and 1.09±0.22 and 1.09±0.12 for the gels containing 0.04, 0.1, 0.2, 0.4, and 1% EGF respectively. The increases in the rate of wound healing were significant with the 0.1, 0.2 and 0.4% EGF. The 0.4% gels resulted in cellular hyperplasia after 5 days of healing. The average tear concentration during the instillation period was 2.87± 0.36 μg/mL and 200.61 ng/mL for the 1% and 0.04% gels respectively. Conclusions. Treatment with EGF in a Carbopol gel carrier for a period of 8 hours results in significant would healing enhancement. The optimum EGF loading in the gel formulation was determined to be 0.4%. EGF delivered via a slow release gel may be an effective way to deliver EGF to the corneal surface.