A: Dilute a suitable volume of Oral Suspension with 0.05Nmethanolic ammonium hydroxide to obtain a solution having a concentration of about 8mg of pyrantel pamoate per mL.Similarly prepare a Standard solution of USP Pyrantel Pamoate RS.Shake both solutions by mechanical means,and centrifuge to obtain clear solutions.Apply a 100-µLportion of each solution to a 20-×20-cm thin-layer chromatographic plate (seeChromatography á621ñ)coated with a 0.50-mm layer of silica gel mixture.Develop the plate in a suitable chromatographic chamber containing the upper phase obtained by shaking together methyl isobutyl ketone,formic acid,and water (2:1:1).Develop the plate until the solvent front is about 2cm from the top edge of the plate.Remove the plate,allow the solvent to evaporate,and examine the plate under UVlight at about 365nm:theRFvalue of the principal spot from the test solution corresponds to that obtained from the Standard solution.

B: [NOTE—Prepare 0.05Nmethanolic ammonium hydroxide by transferring 0.8mLof ammonium hydroxide to a 250-mLvolumetric flask containing 100mLof methanol,diluting with methanol to volume,and mixing.]Dilute a suitable volume of Oral Suspension with 0.05Nmethanolic ammonium hydroxide to obtain a solution having a concentration of about 16mg of pyrantel pamoate per mL.Similarly prepare a Standard solution of USP Pyrantel Pamoate RS.Shake both solutions by mechanical means,and centrifuge to obtain clear solutions.Apply a 20-µLportion of each solution to an 18-×24-cm sheet of chromatographic paper (Whatman No.1or equivalent)that previously has been prepared as follows.Impregnate the paper with a freshly prepared solution obtained by mixing 7volumes of acetone and 3volumes of glycine-sodium chloride-hydrochloric acid buffer solution (prepared by mixing 3volumes of a solution that is 0.3Mwith respect to both glycine and sodium chloride with 7volumes of 0.3Mhydrochloric acid).Press the impregnated paper uniformly between white,nonfluorescent blotters to remove the excess solvent.Place the spotted chromatographic paper in a suitable chromatographic chamber,and develop by descending chromatography (seeChromatography á621ñ),using as the solvent system the upper phase obtained by mixing ethyl acetate,butanol,and water (10:1:1).After developing for 20hours,remove the paper from the chamber,air-dry for 10minutes,transfer to an air-circulating oven,and dry at 60for 30minutes:theRFvalue of the principal spot from the solution under test corresponds to that obtained from the Standard solution.

C: The retention times of the major peaks due to pyrantel base and pamoic acid in the chromatogram of theAssay preparation correspond to those in the chromatogram of theStandard preparation,as obtained in theAssay.

FOR ORAL SUSPENSION PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.

FOR ORAL SUSPENSION PACKAGED IN MULTIPLE-UNIT CONTAINERS: meets the requirements.

Mobile phase,Standard preparation,and Chromatographic system— Proceed as directed in theAssayunderPyrantel Pamoate.

Assay preparation— Transfer by means of a pipet an accurately measured volume of Oral Suspension,equivalent to about 200mg of pyrantel pamoate,into a 100-mLvolumetric flask,disperse,and dilute with water to volume.While stirring the dispersion with a magnetic stirrer,transfer 1.0mLof the aliquot to a 25-mLvolumetric flask,dissolve in and dilute withMobile phase to volume,mix,and filter.

Procedure— Separately inject equal volumes (about 20µL)of theStandard preparation and theAssay preparation into the chromatograph,record the chromatograms obtained for a period of not less than 2.5times the retention times of pyrantel base,and measure the responses for the major peaks.The relative retention times for pamoic acid and pyrantel base are about 0.6and 1.0,respectively.Calculate the quantity,in mg,of pyrantel (C11H14N2S)in each mLof the Oral Suspension taken by the formula: in which 0.347is the ratio of the molecular weight of pyrantel to that of pyrantel pamoate;Cis the concentration,in mg per mL,of USP Pyrantel Pamoate RSin theStandard preparation;Vis the volume,in mL,of Oral Suspension taken;andrUandrSare the peak responses for pyrantel base obtained from theAssay preparation and theStandard preparation,respectively.