Abstract
The present work describes the formulation development of ophthalmic in situ gelling system using thermo-reversible gelling polymer, i.e. Pluronic F 127 (PF127). Because of high concentration (20 to 25%w/v) of this polymer required for in situ gelation causes irritation to the eye. So, to reduce this concentration, an attempt was made to combine the PF127 with other polymers like hydroxy propyl methyl cellulose (HPMC) as a viscosity increasing agent or with polymers like carbopol 940, xanthan gum, and sodium alginate (high glucuronic acid content) showing a pH and cation-triggered sol-gel transition, respectively. Different batches were prepared of varying concentrations of these polymers with PF127 using cromolyn sodium 2%w/v in phosphate buffer pH 5.0. The formulations were optimized by the viscosity measurement and in vitro gelation study. Selected formulations were evaluated for in vitro drug release profile and indicated sustain drug release over a period of 10 h. Effect of sterilization on drug content, pH, clarity, and viscosity were also evaluated. Finally, we concluded that by using this type of combination system, we could reduce not only the concentration of individual polymers but also the side effects without compromising the in vitro gelling capacity as well as overall rheology of the system.
Highlights
One of the main problems encountered in ophthalmic drug delivery is the rapid and extensive elimination of conventional eye drops from the eye
The present study demonstrate that a reduction in pluronic concentration, without compromising the in situ gelling capabilities as well as overall rheological properties of the delivery system, can be achieved by addition of inert polymer acting as viscosity enhancer like hydroxy propyl methyl cellulose (HPMC) or polymer that shows in situ sol-gel transition via another mechanism with desired rheological properties and ability to deliver the drug in sustained manner
Uni., Baroda, Xanthangum obtained from Glasston Ltd, Bhavnagar, Carbopol 940 from Corel Pharma, Ahmedabad, HPMC (Hydroxy propyl methyl cellulose) obtained from Colorcon India Ltd, PVA (Polyvinyl alcohol) and cromolyn sodium were obtained from Indiana Ophthalmic, Bhavnagar
Summary
One of the main problems encountered in ophthalmic drug delivery is the rapid and extensive elimination of conventional eye drops from the eye. This process results in extensive drug loss. Only a small amount (1-6%) penetrates the cornea and reaches the intra ocular tissues.[1,2] The reasons for this inefficient drug delivery includes rapid tear turnover, lachrymal drainage, and drug dilution by tears.[3] The higher drainage rate is due to tendency of the eye to maintain its residence volume at 7-10 μl permanently, whereas volumes of topically instilled range from 20 to 50μl. It has been demonstrated in vivo that
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