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Allopurinol
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C5H4N4O 136.11
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 98.0 percent and not more than 101.0 percent of C5H4N4O, calculated on the dried basis.
Packaging and storage— Preserve in well-closed containers.
Loss on drying 731— Dry it in vacuum at 105 for 5 hours: 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 250 mg of Allopurinol in a mixture of 6 N ammonium hydroxide and 1 N sodium hydroxide (9:1) to make 10.0 mL, and mix.
Standard solution— Dissolve a suitable quantity of USP Allopurinol Related Compound A RS in 6 N ammonium hydroxide to obtain a solution having a known concentration of 50 µg per mL.
Application volume: 10 µL.
Developing solvent system— Shake 200 mL of butyl alcohol and 200 mL of 6 N ammonium hydroxide, discard the lower layer, and add 20 mL of butyl alcohol to the top layer.
Procedure— Proceed as directed for Thin-Layer Chromatography under Chromatography 621. Develop the chromatogram until the solvent front is 1 cm from the top of the plate, air-dry, and examine under UV light. 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 V 467: meets the requirements.
Solvent— Use dimethyl sulfoxide.
Residual solvents 467: meets the requirements.
(Official January 1, 2007)
Assay— Dissolve about 100 mg of Allopurinol, accurately weighed, in 30 mL of dimethylformamide, warming if necessary. Titrate with 0.1 N tetrabutylammonium 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 mL of 0.1 N tetrabutylammonium hydroxide is equivalent to 13.61 mg of C5H4N4O.
Auxiliary Information— Staff Liaison : Elena Gonikberg, Ph.D., Scientist
Expert Committee : (MDGRE05) Monograph Development-Gastrointestinal Renal and Endocrine
USP29–NF24 Page 75
Pharmacopeial Forum : Volume No. 28(5) Page 1386
Phone Number : 1-301-816-8251