Allopurinol
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4H-Pyrazolo[3,4-d]pyrimidin-4-one,1,5-dihydro-.
1,5-Dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one.
1H-Pyrazolo[3,4-d]pyrimidin-4-ol [315-30-0].
»Allopurinol contains not less than 98.0percent and not more than 101.0percent of C5H4N4O,calculated on the dried basis.
Packaging and storage—
Preserve in well-closed containers.
Loss on drying á731ñ—
Dry it in vacuum at 105
for 5hours:it loses not more than 0.5%of its weight.
for 5hours:it loses not more than 0.5%of its weight.
Chromatographic purity—
Adsorbent:
0.1-mm layer of chromatographic cellulose containing a fluorescent indicator.
Test solution—
Dissolve 250mg of Allopurinol in a mixture of 6Nammonium hydroxide and 1Nsodium hydroxide (9:1)to make 10.0mL,and mix.
Standard solution—
Dissolve a suitable quantity of USP Allopurinol Related Compound A RSin 6Nammonium hydroxide to obtain a solution having a known concentration of 50µg per mL.
Application volume:
10µL.
Developing solvent system—
Shake 200mLof butyl alcohol and 200mLof 6Nammonium hydroxide,discard the lower layer,and add 20mLof butyl alcohol to the top layer.
Procedure—
Proceed as directed for Thin-Layer Chromatographyunder Chromatography á621ñ.Develop the chromatogram until the solvent front is 1cm from the top of the plate,air-dry,and examine under UVlight.Any spot in the chromatogram obtained from the Test solution,except for the principal spot,is not more intense than the spot in the chromatogram obtained from the Standard solution:not more than 0.2%of any individual impurity is found.
Organic volatile impurities,Method Vá467ñ:
meets the requirements.
Solvent—
Use dimethyl sulfoxide.
Assay—
Dissolve about 100mg of Allopurinol,accurately weighed,in 30mLof dimethylformamide,warming if necessary.Titrate with 0.1Ntetrabutylammonium hydroxide VS,determining the endpoint potentiometrically,using a calomel-glass electrode system and taking the necessary precautions to prevent the absorption of atmospheric carbon dioxide.Perform a blank determination,and make any necessary correction.Each mLof 0.1Ntetrabutylammonium hydroxide is equivalent to 13.61mg of C5H4N4O.
Auxiliary Information—
Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 67
Pharmacopeial Forum:Volume No.28(5)Page 1386
Phone Number:1-301-816-8251