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.

Topic/Question	Contact	Expert Committee
Monograph	Kahkashan Zaidi, Ph.D. Senior Scientist 1-301-816-8269	(AER05) Aerosols05

USP32–NF27 Page 1641