Determination of Levofloxacin Hydrochloride Ophthalmic in situ Gel by HPLC / 中国药师

Objective:To establish an HPLC method for the determination of levofloxacin in levofloxacin hydrochloride ophthalmic in situ gel. Methods:The chromatographic column was Agilent Zorbax C18(150 mm ×4.6 mm,5μm). The mobile phase consisted of hexane sulfonic acid sodium solution-methanol(72∶28). The flow rate was 1. 0 ml·min-1. The detection wavelength was 293 nm. The chromatographic column temperature was 40℃. The injection volume was 10 μl. Results:The calibration curve was linear within the range of 0. 040 3-0. 403 0 mg·ml-1(r=1. 000 0) for levofloxacin. The average recovery was 99. 8% (RSD=1. 08%,n=9). Conclusion:The method is accurate, simple and rapid, and suitable for the content determination of levofloxacin in levofloxacin hydro-chloride ophthalmic in situ gel.

Evaluation on rheological properties of Dange ophthalmic in-situ gel and its common gel / 中草药

Objective: To determine the rheological properties of Dange ophthalmic in-situ gel and its common gel by using dynamic rheological experiments. Methods: Dange ophthalmic in-situ gel was prepared by adopting Poloxamer as thermosensitive material, and Dange gel was prepared by carbopol. Anton Paar MCR302 Rheometer was used to determine the rheological parameters of above two kinds of gel at different temperatures which speculated the phase transition time and gelling temperature of in-situ gel. Results: Dange ophthalmic in-situ gel was Newtonian liquid at low temperature, with its viscous modulus dominated. It was shear-thinning pseudoplastic fluid under the conditions of phase transition at room temperature, with its elastic modulus dominated. The phase transition temperature (Tg) was (24.4 ± 0.1)°C, and the gelling time was 9 s. Dange gel existed in network structure among a certain temperature range, it was stable and did not change with temperature. Conclusion: The test has established the rheological evaluation system of Dange ophthalmic in-situ gel or its common gel, accurately evaluated the rheological properties of the two gels by dynamic rheological parameters, and it can be used as the basis for the quality control of products.

Preparation and evaluation of pilocarpine nitrate in situ gel for ophthalmic use / 中草药

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.