Ocular poloxamer-based ciprofloxacin hydrochloride in situ forming gels. 
The purpose of this study was to develop poloxamer-based in situ gelling formulations of ciprofloxacin hydrochloride (HCl) aiming at prolonging corneal contact time, controlling drug release, enhancing ocular bioavailability, and increasing patient compliance.  The in situ forming gels were prepared using different concentrations of poloxamer 407 (P407) and poloxamer 188 (P188).  Mucoadhesives such as hydroxypropylmethyl cellulose (HPMC) or hydroxyethyl cellulose (HEC) were added to the formulations to enhance the gel bioadhesion properties.  The prepared formulations were evaluated for their in vitro drug release, sol-gel transition temperature, rheological behavior, and mucoadhesion force.  The in vivo antimicrobial efficacy of selected ciprofloxacin HCl in situ gelling formulations was studied on infected rabbit's eyes and compared with that of the marketed conventional eye drops.  The gelation temperature of the prepared formulations ranged from 28.00 to 34.03 degrees C. Increasing the concentrations of P407, HPMC, and HEC increased the viscosity and mucoadhesion force of the preparations and decreased the in vitro drug release.  Ciprofloxacin HCl in situ forming gel formulae composed of P407/P188/HPMC (18/13/1.5%, wt/wt), and P407/P188/HEC (18/13/0.5%, wt/wt) showed optimum release and mucoadhesion properties and improved ocular bioavailability as evidenced by an enhanced therapeutic response compared with the marketed conventional eye drops.