Packaging and storage— Preserve in well-closed containers,and avoid prolonged exposure to temperatures exceeding 30.

Identification— Digest a quantity of Paste,equivalent to about 1g of carboxymethylcellulose sodium,with 50mLof water until solution is virtually complete,and filter:the filtrate responds to the following tests.

Consistency— Determine as directed in the test for Consistencyunder Petrolatum:the final average of the trials is not less than 30.0mm and not more than 36.0mm,indicating a consistency value between 300and 360.

Microbial limits á61ñ— The total bacterial count does not exceed 1000cfu per g,and the tests for Salmonellaspecies and Escherichia coliare negative.

Loss on drying á731ñ— Dry it at 105for 3hours:it loses not more than 2.0%of its weight.

Heavy metals,Method IIá231ñ— Determine as directed in the test for Heavy metalsunder Methylcellulose,using a 400-mg specimen:the limit is 0.005%.

Assay— Transfer about 2g of Paste,accurately weighed,to a glass-stoppered,250-mLconical flask.Add 75mLof glacial acetic acid,attach a condenser,and reflux for 2hours.Cool,transfer the mixture to a 250-mLbeaker with the aid of small volumes of glacial acetic acid,and titrate with 0.1Nperchloric acid in dioxane VS,determining the endpoint potentiometrically.Each mLof 0.1Nperchloric acid is equivalent to 29.67mg of carboxymethylcellulose sodium.

Expert Committee:(EMC)Excipients:Monograph Content

USP28–NF23Page 359

Phone Number:1-301-816-8323