Methdilazine Hydrochloride Oral Solution
(Monograph under this new title—to become official June 1,2005)
(Current monograph title is Methdilazine Hydrochloride Syrup)
»Methdilazine Hydrochloride Oral Solution contains 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 USP Reference Standard,and solutions containing them,by conducting the procedures without delay,under subdued light,or using low-actinic glassware.
Identification— Transfer a volume of Oral Solution,equivalent to about 4mg of methdilazine hydrochloride,to a 60-mLseparator,add 5mLof 0.1Nhydrochloric acid,and extract with 10mLof ether,discarding the extract.Add 10mLof sodium bicarbonate solution (1in 10)to the separator,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 RSthat has been treated in the same manner.
pHá791ñ: between 3.3and 4.1.
Alcohol content,Method IIá611ñ: between 6.5%and 7.5%of C2H5OH.
Assay—
Standard preparation— Dissolve a suitable quantity of USP Methdilazine Hydrochloride,accurately weighed,in chloroform,and quantitatively dilute with chloroform to obtain a solution having a known concentration of about 400µg per mL.
Assay preparation— Transfer a volume of Oral Solution,equivalent to about 4mg of methdilazine hydrochloride,to a 60-mLseparator,add 10mLof a saturated solution of sodium chloride,and extract with three 10-mLportions of chloroform,transferring the extracts to a 100-mLvolumetric flask.
Procedure— Transfer 10.0mLof Standard preparationto a 100-mLvolumetric flask,and add 20mLof chloroform.To this flask and to the flask containing the Assay preparationadd 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 a mixture of 30mLof chloroform,4mLof palladium chloride TS,and 66mLof alcohol as the blank.Calculate the quantity,in mg,of methdilazine hydrochloride (C18H20N2S·HCl )in each mLof the Oral Solution taken by the formula:
(0.01C/V)(AU/AS),
in which Cis the concentration,in µg per mL,of USP Methdilazine Hydrochloride RSin the Standard preparation;Vis the volume,in mL,of Oral Solution taken;and AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparation,respectively.
(Official June 1,2005)
Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist
Expert Committee:(PA6)Pharmaceutical Analysis 6
USP28–NF23Page 1239
Pharmacopeial Forum:Volume No.28(2)Page 326
Phone Number:1-301-816-8389