Trimethobenzamide Hydrochloride Injection »Trimethobenzamide Hydrochloride Injection is a sterile solution of Trimethobenzamide Hydrochloride in Water for Injection.It contains not less than 95.0percent and not more than 105.0percent of the labeled amount of C21H28N2O5·HCl. Packaging and storage— Preserve in single-dose or in multiple-dose containers,preferably of Type Iglass. USP Reference standards á11ñ USP Endotoxin RS.USP Trimethobenzamide Hydrochloride RS. Identification— A: It meets the requirements of Identificationtest Aunder Trimethobenzamide Hydrochloride Capsules. B: Transfer a volume of Injection,equivalent to about 100mg of trimethobenzamide hydrochloride,to a separator containing 20mLof water.Add 2mLof 1Nsodium hydroxide,and proceed as directed in Identificationtest Bunder Trimethobenzamide Hydrochloride Capsules,beginning with “Extract with 15mLof chloroform.” C: Dilute a portion of Injection quantitatively and stepwise with methanol to obtain a solution containing 2.5mg of trimethobenzamide hydrochloride per mL:this solution meets the requirements of the Thin-layer Chromatographic Identification Test á201ñ,a solvent system consisting of a mixture of ethyl acetate,alcohol,and ammonium hydroxide (90:10:5)being used. Bacterial endotoxins á85ñ It contains not more than 1.80USP Endotoxin Units per mg of trimethobenzamide hydrochloride. pHá791ñ: between 4.5and 5.5. Other requirements— It meets the requirements under Injections á1ñ. Assay— Transfer to a suitable separator an accurately measured volume of Injection,equivalent to about 200mg of trimethobenzamide hydrochloride.Add 5mLof water and 3mLof dilute hydrochloric acid (1in 12),and extract with four 20-mLportions of ether,collecting the ether extracts in a second separator,and transferring the aqueous layer to a 500-mLvolumetric flask.Wash the combined ether extracts with one 20-mLportion of water,transfer the aqueous layer to the 500-mLvolumetric flask,dilute with water to volume,and mix.Dilute 5.0mLof the solution with dilute hydrochloric acid (1in 120)to 100.0mL,and mix.Concomitantly determine the absorbances of this solution and a Standard solution of USP Trimethobenzamide Hydrochloride RSin the same medium having a known concentration of about 20µg per mL,in 1-cm cells at the wavelength of maximum absorbance at about 258nm,with a suitable spectrophotometer,using dilute hydrochloric acid (1in 120)as the blank.Calculate the quantity,in mg,of C21H28N2O5·HCl in each mLof the Injection taken by the formula: (10C/V)(AU/AS), in which Cis the concentration,in µg per mL,of USP Trimethobenzamide RSin the Standard solution,Vis the volume,in mL,of Injection taken,and AUand ASare the absorbances of the solution from the Injection and the Standard solution,respectively. Auxiliary Information— Staff Liaison:Elena Gonikberg,Ph.D.,Scientist Expert Committee:(PA4)Pharmaceutical Analysis 4 USP28–NF23Page 1986 Phone Number:1-301-816-8251