C30H53NO11(av.) 603.00(av.)

Benzoic acid,4-(butylamino)-,2,5,8,11,14,17,20,23,26-nonaoxaoctacos-28-yl ester.
2,5,8,11,14,17,20,23,26-Nonaoxaoctacosan-28-yl p-(butylamino)benzoate [104-31-4].

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

USP Reference standards á11ñ— USP Benzonatate RS.

Identification—

Refractive index á831ñ: between 1.509and 1.511at 20.

Water,Method Iá921ñ: not more than 0.3%.

Residue on ignition á281ñ: not more than 0.1%.

Chloride á221ñ— Mix 20mLof a solution (1in 10)with 20mLof water and 1mLof nitric acid,shake for 1hour,and allow to stand for 1hour.Pass through a filter having a porosity of 0.2µm,and to the filtrate add 1mLof silver nitrate TS.Dilute with water to 50mL,mix,and allow to stand protected from light for 10minutes:the turbidity does not exceed that produced by 0.10mLof 0.020Nhydrochloric acid (0.0035%).

Sulfate á221ñ— Mix 5mLof a solution (1in 20)with 5mLof water and 1mLof 3Nhydrochloric acid,shake for 1hour,and allow to stand for 1hour.Pass through a filter having a porosity of 0.2µm,and to the filtrate add 1mLof barium chloride TS.Mix,and allow to stand for 10minutes:the turbidity does not exceed that produced by 0.10mLof 0.020Nsulfuric acid (0.04%).

Heavy metals,Method IIá231ñ: 0.001%.

Organic volatile impurities,Method Iá467ñ: meets the requirements.

Assay— Weigh accurately about 5g of Benzonatate,and reflux with 25.0mLof 0.5Nsodium hydroxide VSfor 1hour.Cool,add 25mLof water and 10drops of bromothymol blue TS,and titrate the excess alkali with 0.5Nhydrochloric acid VS.Perform a blank determination (see Residual Titrationsunder Titrimetry á541ñ).Each mLof 0.5Nsodium hydroxide is equivalent to 301.5mg of C30H53NO11.

Expert Committee:(PA2)Pharmaceutical Analysis 2

USP28–NF23Page 235

Phone Number:1-301-816-8139