Methdilazine Hydrochloride Tablets, chemical structure, molecular formula, Reference Standards

Methdilazine Hydrochloride Tablets

»Methdilazine Hydrochloride Tablets contain not less than 93.0percent and not more than 107.0percent of the labeled amount of methdilazine hydrochloride (C18H20N2S·HCl).

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

USP Reference standards á11ñ— USP Methdilazine Hydrochloride RS.

NOTE—Throughout the following procedures,protect test or assay specimens,the Reference Standard,and solutions containing them,by conducting the procedures without delay,under subdued light,or using low-actinic glassware.

Identification— Transfer a portion of finely powdered Tablets,equivalent to about 8mg of methdilazine hydrochloride,to a 60-mLseparator,add 10mLof sodium bicarbonate solution (1in 10),and extract with 3mLof chloroform.Filter the extract through a pledget of cotton.Evaporate the chloroform,carefully removing the last trace of solvent in a small vacuum flask:the IRabsorption spectrum of a potassium bromide dispersion of the methdilazine so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Methdilazine Hydrochloride RS,similarly treated and measured.

Dissolution á711ñ—

Medium: water;900mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Determine the amount of C18H20N2S·HCl dissolved from UVabsorbances at the wavelength of maximum absorbance at about 252nm of filtered portions of the solution under test,suitably diluted with Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Methdilazine Hydrochloride RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C18H20N2S·HCl is dissolved in 45minutes.

Uniformity of dosage units á905ñ: meet the requirements.

Assay—

Standard preparation— Dissolve a suitable quantity of USP Methdilazine Hydrochloride RS,accurately weighed,in chloroform,and dilute quantitatively with chloroform to obtain a solution having a known concentration of about 400µg per mL.

Assay preparation— Weigh and finely powder not fewer than 20Tablets,and transfer an accurately weighed portion of the powder,equivalent to about 80mg of methdilazine hydrochloride,to a 200-mLvolumetric flask.Add 60mLof chloroform,shake for 20minutes,dilute with chloroform to volume,and mix.Filter,discarding the first 15mLof the filtrate.Use the subsequent filtrate as directed in the Procedure.

Procedure— Into three separate 100-mLvolumetric flasks transfer 10.0mLeach of the Standard preparation,the Assay preparation,and chloroform to provide the blank.To each flask add 20mLof chloroform and 4.0mLof buffered palladium chloride TS,dilute with alcohol to volume,and mix.Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 460nm,with a suitable spectrophotometer,using the blank to set the instrument.Calculate the quantity,in mg,of methdilazine hydrochloride (C18H20N2S·HCl)in the portion of Tablets taken by the formula:

0.2C(AU/AS),

in which Cis the concentration,in µg per mL,of USP Methdilazine Hydrochloride RSin the Standard preparation;and AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparation,respectively.

Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist

Expert Committee:(PA6)Pharmaceutical Analysis 6

USP28–NF23Page 1240

Phone Number:1-301-816-8389