Metolazone Tablets, chemical structure, molecular formula, Reference Standards

Metolazone Tablets

»Metolazone Tablets contain not less than 90.0%and not more than 110.0%of the labeled amount of metolazone (C16H16ClN3O3S).

Packaging and storage— Preserve in tight,light-resistant containers,and store below 30

USP Reference standards á11ñ— USP Metolazone RS.

Identification,Ultraviolet Absorption á197Uñ—

Solution— Pipet 3mLof the Assay preparationinto a 25-mLvolumetric flask,dilute with methanol to volume,and mix.

Uniformity of dosage units á905ñ: meet the requirements.

Assay— [NOTE—Use low-actinic glassware throughout the Assay.]

Standard preparation— Dissolve an accurately weighed quantity of USP Metolazone RSin alcohol to obtain a solution having a known concentration of about 40µg per mL.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 40mg of metolazone,to a 250-mLvolumetric flask,add 150mLof alcohol,sonicate for 2minutes,dilute with alcohol to volume,and filter.Pipet 25mLof the filtrate into a 100-mLvolumetric flask,dilute with alcohol to volume,and mix.

Procedure— Concomitantly determine the absorbances of the solutions at the wavelength of maximum absorbance at about 343nm,with a suitable spectrophotometer,using alcohol as the blank.Calculate the quantity,in mg,of metolazone (C16H16ClN3O3S)in the portion of Tablets taken by the formula:

C(AU/AS),

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

Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate

Expert Committee:(PA5)Pharmaceutical Analysis 5

USP28–NF23Page 1278

Pharmacopeial Forum:Volume No.29(6)Page 1932

Phone Number:1-301-816-8305