Packaging and storage— Preserve in tight,light-resistant containers,and avoid exposure to excessive heat.

USP Reference standards á11ñ— USP Furazolidone RS.

Identification— Add a quantity of powdered Tablets,equivalent to about 50mg of furazolidone,to 10mLof a freshly prepared mixture of dimethylformamide and alcoholic potassium hydroxide TS(9:1):the solution turns purple,immediately changes to deep blue,and,upon standing for 10minutes,again turns purple.

Uniformity of dosage units á905ñ: meet the requirements.

Assay— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 100mg of furazolidone,to a 250-mLvolumetric flask.Add about 150mLof dimethylformamide,warm to about 50,and sonicate to aid in dissolving the furazolidone.Cool,dilute with dimethylformamide to volume,mix,and centrifuge a portion of the mixture.Transfer 5.0mLof the clear solution so obtained to a 250-mLvolumetric flask,dilute with water to volume,and mix (assay solution).Similarly,dissolve a suitable quantity of USP Furazolidone RS,accurately weighed,in dimethylformamide to obtain a Standard stock solution having a known concentration of about 400µg per mL.Transfer 5.0mLof this stock solution to a 250-mLvolumetric flask,dilute with water to volume,and mix (Standard solution).Concomitantly determine the absorbances of the assay solution and the Standard solution at the wavelength of maximum absorbance at about 367nm,with a suitable spectrophotometer,using dimethylformamide solution (1in 50)as the blank.Calculate the quantity,in mg,of C8H7N3O5in the portion of Tablets taken by the formula: in which Cis the concentration,in µg per mL,of USP Furazolidone RSin the Standard solution;and AUand ASare the absorbances of the assay solution and the Standard solution,respectively.

Expert Committee:(VET)Veterinary Drugs

USP28–NF23Page 875

Phone Number:1-301-816-8178