Makwana S B, Patel V A, Parmar S J
Department of Pharmaceutical Sciences, Sardar Patel University, Vallabh Vidhyanagar 388120, Gujarat, India.
Results Pharma Sci. 2015 Jul 8;6:1-6. doi: 10.1016/j.rinphs.2015.06.001. eCollection 2016.
In situ gels are systems which are applied as solutions or suspensions and are capable of undergoing rapid sol-to-gel transformation triggered by external stimulus such as temperature, pH etc. on instillation. The aim of the present study was to formulate and evaluate pH responsive in-situ gel for ophthalmic delivery. Ciprofloxacin hydrochloride is popularly used as a broad spectrum antibiotic in the treatment of corneal ulcers of ocular infections. However, rapid dilution on instillation, wash out, poor retention of drug concentration delimit the therapeutic benefits of the drug when used in form of conventional eye drops. Sodium alginate, an ophthalmic gel forming mucoadhesive polymer was chosen as polymer which undergoes instantaneous gel formation due to formation of calcium alginate by virtue of its interaction with divalent cation (Ca(+2)) present in lachrymal fluid. Hydroxy Propyl Methyl Cellulose (HPMC K4M and E5 0LV) was further incorporated as a viscosity enhancer in order to achieve the desired consistency so as to facilitate sustained drug release. The developed formulations were evaluated for clarity, pH measurement, gelling capacity, drug content, rheological study, and in vitro drug release. Thus, in situ gel based systems containing gums can be a valuable approach for ophthalmic drug delivery when compared to conventional systems.
原位凝胶是一种以溶液或悬浮液形式应用的体系，在滴注时能够在温度、pH值等外部刺激的触发下迅速发生溶胶到凝胶的转变。本研究的目的是制备并评估用于眼部给药的pH响应性原位凝胶。盐酸环丙沙星作为一种广谱抗生素，常用于治疗眼部感染的角膜溃疡。然而，滴注时的快速稀释、冲洗以及药物浓度的低保留率限制了该药物以传统眼药水形式使用时的治疗效果。海藻酸钠是一种形成眼部凝胶的粘膜粘附聚合物，因其与泪液中存在的二价阳离子（Ca(+2)）相互作用形成海藻酸钙而能瞬间形成凝胶，故被选为聚合物。进一步加入羟丙基甲基纤维素（HPMC K4M和E5 0LV）作为粘度增强剂，以达到所需的稠度，从而促进药物的持续释放。对所开发的制剂进行了澄清度、pH值测定、凝胶化能力、药物含量、流变学研究和体外药物释放评估。因此，与传统体系相比，含胶的原位凝胶体系可能是一种有价值的眼部给药方法。
