Mebendazole Oral Suspension
» Mebendazole Oral Suspension is Mebendazole in an aqueous vehicle. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of mebendazole (C16H13N3O3).
Packaging and storage— Preserve in tight containers at controlled room temperature.
Labeling— Label it to indicate that it is for veterinary use only.
Identification— Mix a quantity of Oral Suspension, equivalent to about 200 mg of mebendazole, with 20 mL of a mixture of chloroform and 96 percent formic acid (19:1). Proceed as directed for Identification under Mebendazole Tablets, beginning with “Warm the suspension on a water bath for a few minutes.” The specified result is obtained.
pH 791: between 6.0 and 7.0.
Assay—
Standard preparation— Transfer about 10 mg of USP Mebendazole RS, accurately weighed, to a 100-mL volumetric flask, and add 90 mL of chloroform, 7 mL of isopropyl alcohol, and 2 mL of 96 percent formic acid. Agitate until the solid has dissolved, add isopropyl alcohol to volume, and mix. Transfer 5.0 mL of this solution to a second 100-mL volumetric flask, dilute with isopropyl alcohol to volume, and mix to obtain a solution having a known concentration of about 5 µg per mL.
Assay preparation 1— Transfer an accurately measured quantity of Oral Suspension, equivalent to about 1000 mg of mebendazole, to a 100-mL volumetric flask, dilute with 96 percent formic acid to volume, and mix. Transfer 10.0 mL of this mixture to a second 100-mL volumetric flask, add 40 mL of 96 percent formic acid, and heat in a water bath at a temperature of 50 for 15 minutes. Cool, add water to volume, mix, and pass through a medium-porosity, sintered-glass filter. Transfer 10.0 mL of the filtrate to a 250-mL separator, and add 50 mL of water and 50 mL of chloroform. Shake for about 2 minutes, allow the phases to separate, and transfer the chloroform layer to a second 250-mL separator. Wash the aqueous layer with two 10-mL portions of chloroform, add the chloroform washings to the second separator, and discard the aqueous layer. Wash the combined chloroform solutions with a mixture of 4 mL of 1 N hydrochloric acid and 50 mL of a 1 in 10 solution of 96 percent formic acid in water, and transfer the chloroform layer to a 100-mL volumetric flask. Extract the aqueous washing with two 10-mL portions of chloroform, add these chloroform extracts to the chloroform solution in the volumetric flask, add 2 mL of 96 percent formic acid and 7 mL of isopropyl alcohol, dilute with chloroform to volume, and mix. Transfer 5.0 mL of this solution to another 100-mL volumetric flask, dilute with isopropyl alcohol to volume, and mix.
Assay preparation 2 (where the Oral Suspension is packaged in syringes calibrated to deliver stated increments of mebendazole)—Express an increment of Oral Suspension to a volumetric flask of an appropriate nominal volume so that when diluted with 96 percent formic acid to volume a mixture containing about 10 mg of mebendazole per mL is obtained. Transfer 10.0 mL of this mixture to a 100-mL volumetric flask, add 40 mL of 96 percent formic acid, and heat in a water bath at a temperature of 50 for 15 minutes. Proceed as directed for Assay preparation 1 beginning with “Cool, add water to volume.”
Procedure— Mix 90 mL of chloroform with 2 mL of 96 percent formic acid in a 100-mL volumetric flask, add isopropyl alcohol to volume, and mix. Transfer 5.0 mL of this solution to a second 100-mL volumetric flask, dilute with isopropyl alcohol to volume, and mix to obtain a reagent blank. Concomitantly determine the absorbances of the relevant Assay preparation and the Standard preparation at the wavelength of maximum absorbance at about 247 nm with a spectrophotometer, using the reagent blank to set the instrument. Calculate the quantity, in mg, of mebendazole (C16H13N3O3) in the portion of Oral Suspension taken to prepare Assay preparation 1 by the formula:
200C(AU / AS)
in which C is the concentration, in µg per mL, of USP Mebendazole RS in the Standard preparation; and AU and AS are the absorbances of Assay preparation 1 and the Standard preparation, respectively. Where appropriate, calculate the quantity, in mg, of mebendazole (C16H13N3O3) in the increment of Oral Suspension taken to prepare Assay preparation 2 by the formula:
20,000(C / V)(AU / AS)
in which V is the volume, in mL, of the volumetric flask into which the increment of Oral Suspension was expressed; AU is the absorbance of Assay preparation 2; and the other terms are as defined above.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Ian DeVeau, Ph.D.
Director, Veterinary Drugs and Radiopharmaceuticals
1-301-816-8178
(VET05) Veterinary Drugs 05
Reference Standards Lili Wang, Technical Services Scientist
1-301-816-8129
RSTech@usp.org
USP32–NF27 Page 2853
Pharmacopeial Forum: Volume No. 32(1) Page 119