ABSTRACT
OBJECTIVE:To optimize the formula of pilocarpine nitrate eye drops by orthogonal test and decision design and to predict the stability of the preparation METHODS:The L9(33)orthogonal test method was used The test was performed according to the storage time and temperature,each of which took three levels to assess the stability and to choose the optimum formula to do the temperature accelerating test and estimate the stability by t0 9 methods RESULTS:The optimum point was pH4,temperature 8℃ and storage time 12 hours The storage period estimated by temperature accelerating test was 76 9 days CONCLUSION:It is simple,quick and accurate to predetermine the stability of pilocarpine nitrate eye drops by methods of orthogonal test and decision design
ABSTRACT
Objective To develop and charaterize a series of Poloxamer-and Carbopol-based in situ gel for ophthalmic use as to enhance the ability of drug to retain in eyes and delay drug release.Methods The gel was prepared using Poloxamer 407/188 and Carbopol 974P as gelling agent and viscosity enhancer,respectively.Rheological characteristics were evaluated and behaviour of drug release in vitro was investigated by modified Franz diffusion cells.Results The rheological study indicated that the gel was physically entangled polymer solutions at 20 ℃ and then converted into a network structure with secondary bonds at 35 ℃.The gel released the drug molecules slowly in 4 h.The best fit model was Higuchi matrix model(r=0.992 3).Formulations consisting of Poloxamer 188 and Carbopol 974P were proved to be able to decrease the drug release speed efficiently.The impact on elastic modulus G" of the gel caused by those two were different.Conclusion An in situ gel with suitable sol-gel transition temperature and satisfactory release pattern could be achieved by adjusting the ratio of Poloxamer 407 to Poloxamer 188.The developed formulations have the ability to prolong the ocular residence time,which suggests it may be a new durg delivery system with bright future.