Related compounds—
TEST 1—
Chromatographic sheet—
Impregnate 18- × 56-cm filter paper (Whatman No. 1 or equivalent) with a freshly prepared 7:3 mixture of acetone and 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.
Test solutions:
0.2 and 20 mg per mL, in a mixture of chloroform, methanol, and ammonium hydroxide (10:10:1).
Standard solutions:
0.2 and 20 mg per mL, in a mixture of chloroform, methanol, and ammonium hydroxide (10:10:1).
Application volume:
20 µL.
Developing solvent system:
a mixture of ethyl acetate, butyl alcohol, and water (10:1:1).
Procedure—
Proceed as directed for
Descending Chromatography under
Chromatography 
621
. Develop for 16 to 20 hours. Remove the sheet from the chamber, air-dry for 10 minutes, transfer to an air-circulating oven, and dry at 60
for 30 minutes. Examine the chromatogram on a 254-nm UV scanner screen: the
RF value of the principal spot from the
Test solution corresponds to that obtained from the appropriate
Standard solution; and no spot in the chromatogram of the more concentrated
Test solution, other than the principal spot, is larger or more intense than the principal spot from the less concentrated
Test solution.
TEST 2—
Adsorbent:
0.25-mm layer of chromatographic silica gel mixture.
Test stock solution—
Transfer about 100 mg of Pyrantel Pamoate, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with dimethylformamide to volume, and mix.
Test solution—
Transfer 1.0 mL of the Test stock solution to a 100-mL volumetric flask, dilute with dimethylformamide to volume, and mix.
Standard solution—
Transfer about 50 mg of
USP Pyrantel Pamoate RS to a 5-mL volumetric flask, dilute with dimethylformamide to volume, and mix.
Developing solvent system:
a mixture of ethyl acetate, water, and glacial acetic acid (3:1:1).
Procedure—
Proceed as directed for
Thin-Layer Chromatography under
Chromatography 621, except to line the developing chamber with filter paper, and allow to equilibrate. Apply 5-µL portions of the
Test stock solution, the
Test solution, and the
Standard solution to the plate, and allow to dry. Develop the chromatogram until the solvent front has moved about 10 cm. Remove the plate from the developing chamber, and allow to air-dry for about 10 minutes. Examine the plate under short-wavelength UV light. The chromatograms obtained from the
Test stock solution and the
Test solution exhibit spots for pyrantel and the pamoate moiety at relative positions corresponding to those obtained from the chromatogram of the
Standard solution: the
RF value of pyrantel is about 0.3, and the
RF value of the pamoate moiety is about 0.8. No spot obtained from the
Test stock solution, other than that of pyrantel and the pamoate moiety, is more intense than the pyrantel spot obtained from the
Test solution.
Content of pamoic acid—
Mobile phase and Chromatographic system—
Prepare as directed in the Assay.
Standard solution—
Dissolve an accurately weighed quantity of
USP Pamoic Acid RS in
Mobile phase to obtain a solution having a known concentration of about 0.52 mg per mL. Transfer 1.0 mL of this solution to a 10-mL volumetric flask, dilute with
Mobile phase to volume, and mix.
Test solution—
Use the Assay preparation.
Procedure—
Inject equal volumes (about 20 µL) of the
Standard solution and the
Test solution into the chromatograph, record the chromatograms, and record the peak responses as directed in the
Assay. Calculate the quantity, in mg, of C
23H
16O
6 in the portion of Pyrantel Pamoate taken by the formula:
1000C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Pamoic Acid RS in the
Standard solution and
rU and
rS are the peak responses for pamoic acid obtained from the
Test solution and the
Standard solution, respectively: the content of pamoic acid is between 63.4% and 67.3%, calculated on the dried basis.
Assay—
[NOTE—Use low-actinic glassware in preparing solutions of pyrantel pamoate, and otherwise protect the solutions from unnecessary exposure to bright light. Complete the
Assay without prolonged interruption.
]
Mobile phase—
Prepare a mixture of acetonitrile, acetic acid, water, and diethylamine (92.8:3:3:1.2), filter, and degas. Make adjustments if necessary (see
System Suitability under
Chromatography 621).
[NOTE—Increasing the amount of acetonitrile in
Mobile phase increases retention times. Increasing the amount of acetic acid, water, and diethylamine decreases retention times. Should the
Mobile phase need to be adjusted, maintain the ratios among acetic acid, water, and diethylamine (1:1:0.4).
]
Standard preparation—
Prepare a solution in
Mobile phase having an accurately known concentration of about 80 µg of
USP Pyrantel Pamoate RS per mL.
Assay preparation—
Transfer about 80 mg of Pyrantel Pamoate, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix. Dilute 1.0 mL of this solution with Mobile phase to 10.0 mL, and mix.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 288-nm detector and 4.6-mm × 25-cm column that contains packing L3. The flow rate is about 1.0 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the resolution,
R, between pyrantel and pamoic acid is not less than 10.0; the number of theoretical plates for the pyrantel peak is not less than 8000; the tailing factor for the pyrantel peak is not greater than 1.3; and the relative standard deviation for replicate injections is not more than 1.0%.
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, and measure the responses for the major peaks. The relative retention times for pamoic acid and pyrantel are about 0.6 and 1.0, respectively. Calculate the quantity, in mg, of C
34H
30N
2O
6S in the portion of Pyrantel Pamoate taken by the formula:
1000C(rU / rS),
in which
C is the concentration, in mg, of
USP Pyrantel Pamoate RS in the
Standard preparation, and
rU and
rS are the peak responses for pyrantel obtained from the
Assay preparation and the
Standard preparation, respectively.
;)
