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

USP Reference standards 11— USP Furazolidone RS.

Identification— Add a quantity of powdered Tablets, equivalent to about 50 mg of furazolidone, to 10 mL of 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 10 minutes, again turns purple.

Uniformity of dosage units 905: meet the requirements.

Residual solvents 467: meet the requirements.

Assay— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 100 mg of furazolidone, to a 250-mL volumetric flask. Add about 150 mL of 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 5.0 mL of the clear solution so obtained to a 250-mL volumetric 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 400 µg per mL. Transfer 5.0 mL of this stock solution to a 250-mL volumetric 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 367 nm, with a suitable spectrophotometer, using dimethylformamide solution (1 in 50) as the blank. Calculate the quantity, in mg, of C8H7N3O5 in the portion of Tablets taken by the formula: in which C is the concentration, in µg per mL, of USP Furazolidone RS in the Standard solution; and AU and AS are the absorbances of the assay solution and the Standard solution, respectively.

Expert Committee : (VET05) Veterinary Drugs 05

USP29–NF24 Page 972

Phone Number : 1-301-816-8178