A: Dilute a suitable volume of Oral Suspension with 0.05 N methanolic ammonium hydroxide to obtain a solution having a concentration of about 8 mg 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-µL portion of each solution to a 20- × 20-cm thin-layer chromatographic plate (see Chromatography 621) 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 2 cm from the top edge of the plate. Remove the plate, allow the solvent to evaporate, and examine the plate under UV light at about 365 nm: the RF value of the principal spot from the test solution corresponds to that obtained from the Standard solution.

B: [NOTE—Prepare 0.05 N methanolic ammonium hydroxide by transferring 0.8 mL of ammonium hydroxide to a 250-mL volumetric flask containing 100 mL of methanol, diluting with methanol to volume, and mixing.] Dilute a suitable volume of Oral Suspension with 0.05 N methanolic ammonium hydroxide to obtain a solution having a concentration of about 16 mg 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-µL portion of each solution to an 18- × 24-cm sheet of chromatographic paper (Whatman No. 1 or equivalent) that previously has been prepared as follows. Impregnate the paper with a freshly prepared solution obtained by mixing 7 volumes of acetone and 3 volumes of glycine-sodium chloride-hydrochloric acid buffer solution (prepared by mixing 3 volumes of a solution that is 0.3 M with respect to both glycine and sodium chloride with 7 volumes of 0.3 M hydrochloric 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 (see Chromatography 621), using as the solvent system the upper phase obtained by mixing ethyl acetate, butanol, and water (10:1:1). After developing for 20 hours, remove the paper from the chamber, air-dry for 10 minutes, transfer to an air-circulating oven, and dry at 60 for 30 minutes: the RF value 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 the Assay preparation correspond to those in the chromatogram of the Standard preparation, as obtained in the Assay.

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

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

(Official January 1, 2007)

Mobile phase, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Pyrantel Pamoate.

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

Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms obtained for a period of not less than 2.5 times 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 0.6 and 1.0, respectively. Calculate the quantity, in mg, of pyrantel (C11H14N2S) in each mL of the Oral Suspension taken by the formula: in which 0.347 is the ratio of the molecular weight of pyrantel to that of pyrantel pamoate; C is the concentration, in mg per mL, of USP Pyrantel Pamoate RS in the Standard preparation; V is the volume, in mL, of Oral Suspension taken; and rU and rS are the peak responses for pyrantel base obtained from the Assay preparation and the Standard preparation, respectively.