rhEGF/HP-β-CD complex in poloxamer gel for ophthalmic delivery

The purpose of the present study is to prepare chemically and physically stable rhEGF/poloxamer gel and to investigate its possibility of ophthalmic delivery. The rhEGF/HP-beta-CD complex markedly increased rhEGF stability compared with rhEGF solution at 4 degrees C. The poloxamer gel was composed of poloxamer 407 (16%) and poloxamer 188 (14%). Additive of rhEGF/HP-beta-CD complexes increased the gelation temperature and 0.5% rhEGF/HP-beta-CD complex exhibited a suitable gelation temperature (35.5 degrees C). The gel strength and bioadhesive force decreased by increasing the rhEGF and HP-beta-CD ratio from 1:4 to 1:20 in the complex. The in vitro release of rhEGF from poloxamer gel containing 1:4 rhEGF/HP-beta-CD complex was much slower than that of rhEGF solution and faster than that of 1:20 rhEGF/HP-beta-CD complex. After ocular administration of poloxamer gels in the rabbit, the concentration of rhEGF in tear declined at a first-order elimination. The poloxamer gel containing rhEGF/HP-beta-CD complex increased the area under the concentration-time curve (AUC) of rhEGF in tear fluid compared with gel containing rhEGF solution. 1:20 ratio of rhEGF/HP-beta-CD exhibited high AUC, indicating that rhEGF may be retained in the pre-corneal area for prolonged period. Therefore, the poloxamer gel could be applicable for the development of effective ophthalmic delivery.