Study On A Liposomal-Hydrogel Ophthalmic Delivery System Of Timolol Meleate

The main drawback of traditional eye drops is their poor bioavailability. After administration, they are diminished by tear fluid quickly. And the sensitivity and protection mechanisms of the eye promote more effective drug delivery systems with better compliancy to be developed. In this thesis, Timolol Maleate was selected as a model drug. A liposomal eye drops and liposomal-hydrogel were designed, and a series of relative researches were carried out. The present paper including:1. The UV spectrophotometry was used for the quantitation of Timolol Maleate in the liposomes, with a detecting wavelength of 296nm. The linearity, precision and recovery were certified by methodological examination. Timolol Maleate’ s lipid-water partition coefficient in different buffer solution were tested.2. A method of Sephadex-column separation-UV spectrophotometry was developed to determine the encapsulation efficiency of TM contained liposomes. The ammonium sulfate gradients and pH regulation methods was employed for the manufacture of Timolol Maleate liposomes. The EN of the drug was more than 90%.3. The physicochemical properties of liposomes were studies. The morphological characteristic of liposome samples was revealed under transmission electron microscope. The liposomes were small and uniformity,with mean size is 187nm,and without charge.4. The permeability characteristics of TM across the cornea of an isolated rabbit were studied in vitro using a variety permeability enhancers. Transcultol P showed a significant improvement permeability without toxity to the cornea of an isolated rabbit. The liposomes solution showed a higher corneal permeability than the eye drops.5. As the hydrogel mateix, the concentration of HPMC was 1.0%. And the storage stability and the pre-corneal retention of liposome-containing-hydrogel were studied. 6. Liposome-contained-hydrogel was investigated on the eyes of normal and glaucomatous pigmented rabbits. The results showed that administration with liposomal-gel displayed more prolonged effect and reduced IOP compared with the control solution.