Methdilazine Hydrochloride Tablets

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

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

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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 8 mg of methdilazine hydrochloride, to a 60-mL separator, add 10 mL of sodium bicarbonate solution (1 in 10), and extract with 3 mL of 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 IR absorption 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

711

—

Medium: water; 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C18H20N2S·HCl dissolved from UV absorbances at the wavelength of maximum absorbance at about 252 nm 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 RS in the same Medium.

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

Uniformity of dosage units

905

: 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 400 µg per mL.

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

Procedure— Into three separate 100-mL volumetric flasks transfer 10.0 mL each of the Standard preparation, the Assay preparation, and chloroform to provide the blank. To each flask add 20 mL of chloroform and 4.0 mL of 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 460 nm, 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 C is the concentration, in µg per mL, of USP Methdilazine Hydrochloride RS in the Standard preparation; and AU and AS are the absorbances of the solutions from the Assay preparation and the Standard preparation, respectively.

Auxiliary Information— Please check for your question in the FAQs before contacting USP.

Topic/Question	Contact	Expert Committee
Monograph	Feiwen Mao, M.S. Senior Scientific Liaison 1-301-816-8320	(SM32010) Monographs - Small Molecules 3
Reference Standards	RS Technical Services 1-301-816-8129 rstech@usp.org
711	Margareth R.C. Marques, Ph.D. Senior Scientific Liaison 1-301-816-8106	(GCDF2010) General Chapters - Dosage Forms

USP35–NF30 Page 3846