Pyrvinium Pamoate Oral Suspension
» Pyrvinium Pamoate Oral Suspension contains, in each 100 mL, an amount of pyrvinium pamoate equivalent to not less than 0.90 g and not more than 1.10 g of pyrvinium (C26H28N3+).
Packaging and storage— Preserve in tight, light-resistant containers.
Identification— The absorption spectrum, between 300 nm and 600 nm, of the solution employed for measurement of absorbance in the Assay exhibits maxima and minima at the same wavelengths as that of a similar solution of USP Pyrvinium Pamoate RS, concomitantly measured.
Uniformity of dosage units 905
for oral suspension packaged in single-unit containers: meets the requirements.
Deliverable volume 698
for oral suspension packaged in multiple-unit containers: meets the requirements.
pH 791: between 6.0 and 8.0, determined potentiometrically.
Assay— [note—Use low-actinic flasks in preparing the solutions, and otherwise protect the solutions from unnecessary exposure to bright light. Complete the assay without prolonged interruption.] Using a pipet calibrated “to contain,” transfer 5 mL of Oral Suspension, freshly mixed and free from air bubbles, to a 250-mL volumetric flask. Complete the transfer by rinsing the pipet with 10 mL of methanol. Add 100 mL of glacial acetic acid, and mix to dissolve the pyrvinium pamoate. Dilute this solution with methanol to volume, and mix. Transfer 3 mL of the resulting solution to a 100-mL volumetric flask, dilute with methanol to volume, and mix. Dissolve an accurately weighed quantity of USP Pyrvinium Pamoate RS in glacial acetic acid, using 4 mL for each 3 mg taken, and dilute quantitatively and stepwise with methanol to obtain a Standard solution having a known concentration of about 9 µg per mL. Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 505 nm, with a suitable spectrophotometer, using methanol as the blank. Calculate the quantity, in g per 100 mL, of pyrvinium (C26H28N3+) in the Oral Suspension taken by the formula:
0.1667C(0.6644AU / AS)
in which C is the concentration, in µg per mL, of USP Pyrvinium Pamoate RS in the Standard solution, calculated on the anhydrous basis; 0.6644 is the ratio of the molecular weight of pyrvinium to one-half the molecular weight of pyrvinium pamoate; and AU and AS are the absorbances of the solution prepared from the Oral Suspension and the Standard solution, respectively.
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Topic/Question Contact Expert Committee
Monograph Behnam Davani, Ph.D., M.B.A.
Senior Scientist
(MDAA05) Monograph Development-Antivirals and Antimicrobials
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 3456
Pharmacopeial Forum: Volume No. 29(6) Page 1977