Abdullah Khan, et al. Int J Pharm 2013; 3(1): 66-72 ISSN 2249-1848 www.pharmascholars.com 66 Research Article CODEN: IJPNL6 DEVELOPMENT OF pH BASED PHASE CHANGE SOLUTIONS FOR OPHTHALMIC DRUG DELIVERY OF GATIFLOXACIN Abdullah Khan * 1 , SMd Noorulla 2 , Mohammed Muqtader 3 , Roshan S 3 and Sadath Ali 4 1 KPJ Healthcare University College, Nilai, Malaysia 2 Department of Pharmacy, CMJ University, Shillong, Meghalaya 3 Department of Pharmacy, Singhania University, Rajasthan 4 Himalayan Institute of Pharmacy & Research, Dehradun, Uttarakhand *Corresponding author e-mail: abdullah2020@rediffmail.com ABSTRACT Conventional dosage forms like gels and eye drops show relatively low bioavailability due to poor precorneal contact time. In situ gelling systems are of great importance in providing prolonged ocular drug delivery due to their elastic properties. It resists ocular drainage leading to longer contact time. In the present study an in situ gelling solution was formulated for gatifloxacin an antibacterial agent, using different ratios of hydroxypropyl cellulose and Sodium alginate with a view to increase gelling strength and bio-adhesion force in order to increase pre-corneal contact time, thereby increasing ocular bioavailability of the drug. The prepared formulations were evaluated for various physical parameters such as, clarity, pH, viscosity, drug content, sterility, and in vitro drug release. The formulated gels were transparent, uniform in consistency and had sufficient spreadability with a pH range of 6.8 to 7.1. It was found that with an increase in the concentration of the bioadhesive polymer sodium alginate the drug release was prolonged for longer period of time. Amongst the different polymer combinations studied the G-7 showed satisfactorily higher gel strength, and sustained drug release for more than twelve hours and was stable throughout the stability studies. Thus it can be concluded that the G-7 was more suitable combination for the formulation of ophthalmic in situ gelling system for sustained ocular drug delivery of gatifloxacin, which improves the bioavailability of the drugs on the precorneal area. Keywords: Ophthalmic In situ gel, Gatifloxacin, Bioadhesive polymers, Sodium Alginate. INTRODUCTION Topical administration of drugs to the eye is the most common method for the treatment of various ocular diseases. This route shows low bioavailability of drugs because of low residence volume (7-10 μl), loss of administered dose due to rapid elimination of drug by nasolachrymal duct, non-productive absorption through conjunctiva leading to some undesirable side effects. To overcome these problems various ophthalmic dosage forms, such as viscous solutions, ointments, gels or polymeric inserts have been prepared to improve the ocular residence time of medications for topical application to the eye [1,2,3] . The rapid elimination of the eye drops administered often results in a short duration of the therapeutic effect which gives multiple dosing regimen necessary. Ocular administration of drug would be significantly improved if the precorneal residence time of drugs could be increased. Several novel formulations have been developed for ophthalmic use, not only to prolong the contact time to the ocular surface, but also to slow down drug elimination from ocular surface [4] . Many reports have been published about ocular inserts and collagen shields, however, these formulations have poor patient compliance. These problems can be overcome by the use of polymeric solutions, which can be formulated as a liquid dosage form, to be administered into the eye, upon exposure to physiological conditions, such as International Journal of Pharmacy Journal Homepage: http://www.pharmascholars.com