Benzocaine Topical Aerosol
»Benzocaine Topical Aerosol is a solution of Benzocaine in a pressurized container. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C9H11NO2.
Packaging and storage Preserve in pressurized containers, and avoid exposure to excessive heat.
Identification Spray a portion of Topical Aerosol into a beaker, and heat on a steam bath for a few minutes to expel residual propellant. A portion of this solution, equivalent to about 5 mg of benzocaine, responds to the Identification test under Benzocaine Topical Solution.
Other requirements It meets the requirements for Pressure Test, Minimum Fill, and Leakage Test under Aerosols, Nasal Sprays, Metered-Dose Inhalers, and Dry Powder Inhalers 601.
Assay Spray a portion of Topical Aerosol into a beaker, and heat on a steam bath for a few minutes to expel residual propellant. Cool, and transfer an accurately weighed portion of the solution, equivalent to about 200 mg of benzocaine, to a 250-mL beaker. Add 50 mL of water and 5 mL of hydrochloric acid, and stir. Cool the solution in an ice bath to about 10, and titrate slowly with 0.1 M sodium nitrite VS, determining the endpoint potentiometrically, using a calomel-platinum electrode system. Perform a blank determination, and make any necessary correction. Each mL of 0.1 M sodium nitrite is equivalent to 16.52 mg of C9H11NO2.