Pyrvinium Pamoate Tablets
»Pyrvinium Pamoate Tablets contain an amount of pyrvinium pamoate equivalent to not less than 92.0percent and not more than 108.0percent of the labeled amount of pyrvinium (C26H28N3+).
Packaging and storage— Preserve in tight,light-resistant containers.
Identification— Tablets respond to the Identificationtest under Pyrvinium Pamoate Oral Suspension.
Uniformity of dosage units á905ñ: meet the requirements.
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.]Place a number of Tablets,equivalent to 500mg of pyrvinium,in a 500-mLvolumetric flask,and add 25mLof water and 25mLof acetone.Completely disintegrate the tablets by heating on the steam bath for 10minutes with frequent mixing,allowing part of the acetone to boil off slowly.To the hot mixture add 250mLof glacial acetic acid,and mix occasionally for 5minutes without further heating,to dissolve the pyrvinium pamoate.Dilute with methanol to volume at room temperature,and mix.Centrifuge a portion of the mixture until a clear solution is obtained.Transfer 3mLof the clear supernatant to a 500-mLvolumetric flask,dilute with methanol to volume,and mix.Dissolve an accurately weighed quantity of USP Pyrvinium Pamoate RSin glacial acetic acid,using 1mLfor each 3mg taken,and dilute quantitatively and stepwise with methanol to obtain a Standard solution having a known concentration of about 9µg per mL.Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 505nm,with a suitable spectrophotometer,using methanol as the blank.Calculate the quantity,in mg,of pyrvinium (C26H28N3+)in the portion of Tablets taken by the formula:
83.3C(0.6644AU/AS),
in which Cis the concentration,in µg per mL,of USP Pyrvinium Pamoate RSin the Standard solution,calculated on the anhydrous basis,0.6644is the ratio of the molecular weight of pyrvinium to one-half the molecular weight of pyrvinium pamoate,and AUand ASare the absorbances of the solution from the Tablets and the Standard solution,respectively.
Auxiliary Information— Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 1688
Phone Number:1-301-816-8394