Preparation and rheological evaluation of ribavirin ophthalmic in situ-gel☆

Liu Zhi-dong, Li Jia-wei, Liu Rui, Zhang Xin-hua, Zhao Zheng

Engineering Research Center of Modern Chinese Medicine Discovery and Preparation Technique，Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin   300193, China

Liu Zhi-dong★, Doctor, Assistant Researcher, Engineering Research Center of Modern Chinese Medicine Discovery and Preparation Technique，Ministry of Education, Tianjin University of Traditional Chinese Medicine, Tianjin   300193, China   lonerliuzd@163.com 

Received: 2008-04-29   Accepted: 2008-05-16   (54200804280012/Y)

Liu ZD, Li JW, Liu R, Zhang XH, Zhao Z.Preparation and rheological evaluation of ribavirin ophthalmic in situ-gel.Zhongguo Zuzhi Gongcheng Yanjiu yu Linchuang Kangfu 2008;12(27): 5374-5376(China)
[www.zglckf.com/zglckf/ejournal/upfiles/ 08-27/27k-5374 (ps).pdf]

Abstract
BACKGROUND: Ribavirin is easily diluted by lacrimal fluid and has low bioavailability. In situ ophthalmic gel changes from liquid drug to gel phase upon exposure to physiological conditions, resulting in an increase in the precorneal residence time of drugs.
OBJECTIVE: To prepare ribavirin in situ ophthalmic gel and valuate its rheological feature.
DESIGN, TIME AND SETTING: In vitro controlled observation, performed at the Engineering Research Center of Modern Chinese Medicine Discovery and Preparation Technique，Ministry of Education, Tianjin University of Traditional Chinese Medicine between September and October 2006.
MATERIALS: Sodium alginate, Carbopol, and ribavirin.
METHODS: Sodium alginate (1% and 2%) and Carbopol (0.3%, 0.6%, and 2%) were combined at different proportions to prepare in situ ophthalmic gel, then in which ribavirin was added.
MAIN OUTCOME MEASURES: Viscosity determinations of prepared different concentrations of formulations were determined using a cone and plate viscometer.
RESULTS: Ribavirin in situ ophthalmic gel prepared with 1% sodium alginate and 0.6% Carbopol had the largest viscosity. The viscosity change was not influenced by the addition of ribavirin. The in situ ophthalmic gel prepared with sodium alginate and Carbopol changed to the gel phase upon exposure to lacrimal fluid.
CONCLUSION: 1% sodium alginate and 0.6% Carbopol produced the best rheological feature and could prolonge the precorneal residence time of drug than that of conventional ophthalmic solution.