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 11— USP Benzonatate RS.

Identification—

Refractive index 831: between 1.509 and 1.511 at 20.

Water, Method I 921: not more than 0.3%.

Residue on ignition 281: not more than 0.1%.

Chloride 221— Mix 20 mL of a solution (1 in 10) with 20 mL of water and 1 mL of nitric acid, shake for 1 hour, and allow to stand for 1 hour. Pass through a filter having a porosity of 0.2 µm, and to the filtrate add 1 mL of silver nitrate TS. Dilute with water to 50 mL, mix, and allow to stand protected from light for 10 minutes: the turbidity does not exceed that produced by 0.10 mL of 0.020 N hydrochloric acid (0.0035%).

Sulfate 221— Mix 5 mL of a solution (1 in 20) with 5 mL of water and 1 mL of 3 N hydrochloric acid, shake for 1 hour, and allow to stand for 1 hour. Pass through a filter having a porosity of 0.2 µm, and to the filtrate add 1 mL of barium chloride TS. Mix, and allow to stand for 10 minutes: the turbidity does not exceed that produced by 0.10 mL of 0.020 N sulfuric acid (0.04%).

Heavy metals, Method II 231: 0.001%.

Organic volatile impurities, Method I 467: meets the requirements.

Residual solvents 467: meets the requirements.

Assay— Weigh accurately about 5 g of Benzonatate, and reflux with 25.0 mL of 0.5 N sodium hydroxide VS for 1 hour. Cool, add 25 mL of water and 10 drops of bromothymol blue TS, and titrate the excess alkali with 0.5 N hydrochloric acid VS. Perform a blank determination (see Residual Titrations under Titrimetry 541). Each mL of 0.5 N sodium hydroxide is equivalent to 301.5 mg of C30H53NO11.

Expert Committee : (MDCCA05) Monograph Development-Cough Cold and Analgesics

USP29–NF24 Page 256

Phone Number : 1-301-816-8139