Study On Preparation And Property Of The Degradable Biomedical Composite Membrane For Ophthalmic Disease

Eye-tissue has an acute sensibilities and particular function, so drug are accessible to ocular barrier and difficult to reach effective concentration in intraocular tissue. This could cause lower utilization of drug, and possibly given users noxious side effect for hormone drug absorbed.Suitable implants, composite drug membranes, implanting under scleral flap for glaucoma or into suprachoroid space for perforating ocular injury were developed in this paper. The model drug in film could maintain sustained release. Thus it was advantageous to alleviate side effect to ocular tissue with an acute change in drug concentration and enhance utilization of drug. The main contents and conclusions in this paper are as follows:The composite membranes with different molecular weight, including PDLLA films, chitosan films, gelatin/chitosan films (GICS) containing different ratio gelatin and carboxymethyl chitosan films (N,O-CMC), were prepared. By degradation examination, four type membranes compared their degraded time, their pH and physical change. The structure of chitosan and GICS films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (X-RD), Scanning electron microscopy (SEM). And the properties of chitosan, GICS and N,O-CMC films were investigated by the swelling ability, tensile test, and blood compatibility experiment. The results showed that the composite film composed of chitosan (M_W=300k) and 25% gelatin was best in integrated performance. N,O-CMC film had good application in the future. So the films of GICS and N,O-CMC were both suitable carriers.Triamcinolone acetonaide (TA) and hydrocortisone sodium succinate (HSS) were used as model drugs. The composite drug membranes of GICS-TA, GICS-HSS and N,O-CMC-HSS), respectively, were prepared. The structures of GICS-TA and N, O-CMC-HSS were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (X-RD), scanning electron microscopy (SEM). The results showed that there was good compatibility between drug and carrier. The drug dispersed in the film in crystallite and connected with tiny hole. This structure was advantageous to release drug. There were only interactional hydrogen bonds between the molecules of drug, gelatin and chitosan, no chemical bond. So the drug membranes remained full functions of drug activity.The release of drug from GICS-TA, GICS-HSS and N,O-CMC-HSS with a filmy PDLLA(N,O-CMC-HSS-P) in vitro showed sustained liberation was achieved, GICS-TAliberation after 35 days only reached 80% and GICS-HSS only remained release for 20days. While N,O-CMC-HSS-P could kept drug liberation over 5 days. Because the differences of drug release between in vitro and in vivo, drug couldn't be absorbed at once. The absorption in vivo might be delayed and the release could maintain longer time.The GICS-TA films were respectively implanted in rabbit eye on operation of perforating ocular injury and glaucoma trabeculectomy. Compared with normal control group, the group of GICS-TA had better effect, such as good biocompatibility of carrier in rabbit eye, better effect in diminish inflammation, proliferation reaction, effective filtering and perfect ophthalmotonus. This drug membrane would be a good new method in therapy of glaucoma and perforating ocular injury in the future. And the drug film implanted in rabbit eye became pieces after 8 weeks. This was faster than pure chitosan film needed 12 weeks in vivo.