Formulation Characterization and Optimization of Buccal Film of Local Anesthetic

Abstract

Benzocaine is the most widely used as a local anesthetic as its produce reversible loss of sensation and temporary relive from the local pain. Benzocaine is available in the number of formulation like gels, cream, ointment, suspension, lozenges, tablet and spray. Among all, the semisolid formulations of benzocaine are widely used for the treatment of mouth ulcer, as they provide the comparatively higher retention of drug in oral cavity by slow release of drug and ease of application on specific location. However, longer stay of such formulation cause patient incompliance and difficulty in eating. To overcome the above drawbacks, the aim of the present study was to formulate and characterize the novel sustained release buccal film containing local anesthetic that could be hold for longer period into oral cavity which provides constant release of the drug for the longer period. A number of film forming polymers (HPMC 15cps, HPMC K4M, Pectin, Carbopol 934, HPC, PVP, PVA and Chitosan) were explored alone and in different combinations to obtain the film formulation by solvent casting method; with desired characteristics like tensile strength, % elongation, folding endurance and drug release. Experiments were also performed to optimize casting surface and amount of plasticizer to obtain the better film properties. Based on the preliminary trials, Chitosan and PVA (poly vinyl alcohol) were found to be promising polymers in combination. To further optimize the film formulation, 32 full factorial design was applied by selecting three different amounts of both polymers (Chitosan and PVA). All nine batches were evaluated for tensile strength, % elongation, drug diffusion (using Franz diffusion cell) and drug release (in USP apparatus – II) using simulated salivary fluid. The results were analyzed by multi-linear regression to generate polynomial equations for various responses. The optimized batches were identified and formulated by generating the overlay contour plots to obtain the desired region. The optimized formulation were compared with the market formulations (semi-solid) for drug release study. It was concluded that the film formulation of benzocaine is promising formulation with improved retention time and desired drug release.