Packaging and storage— Preserve in tight,light-resistant containers.

Identification— Transfer a volume of Otic Solution,equivalent to about 2.5mg of benzocaine,to a small beaker,add 10mLof water,and dissolve with the aid of a few drops of 3Nhydrochloric acid.Add 5drops of sodium nitrite solution (1in 10),then add 2mLof a solution of 100mg of 2-naphthol in 5mLof 1Nsodium hydroxide:an orange-red precipitate is formed.

Microbial limits á61ñ— It meets the requirements of the tests for absence of Salmonellaspecies and Escherichia coliand for absence of Staphylococcus aureusand Pseudomonas aeruginosa;the total aerobic microbial count is less than 100cfu per mL.

Assay— Transfer an accurately measured volume of Otic Solution,equivalent to about 400mg of benzocaine,to a beaker,add 150mLof cold 1.6Nhydrochloric acid,and stir until a fine dispersion is obtained.Cool the solution in an ice bath to about 10,and titrate slowly with 0.1Msodium nitrite VS,determining the endpoint potentiometrically,using a calomel-platinum electrode system.Perform a blank determination,and make any necessary correction.Each mLof 0.1Msodium nitrite is equivalent to 16.52mg of C9H11NO2.

Expert Committee:(PA1)Pharmaceutical Analysis 1

USP28–NF23Page 230

Phone Number:1-301-816-8379