Allopurinol Tablets
Action and use
Xanthine oxidase inhibitor; treatment of gout and hyperuricaemia.
Definition
Allopurinol Tablets contain Allopurinol.
Content of allopurinol, C5H4N4O
92.5 to 107.5% of the stated amount.
Identification
TEST
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
The test is not valid unless in solution (3) the resolution factor between the peaks corresponding to impurity A and allopurinol is at least 3.
Inject solution (3). When the chromatogram is recorded in the prescribed conditions, the retention times are: impurity A, about 4.2 minutes; impurities B and C, about 6.1 minutes; allopurinol, about 7.7 minutes; impurity D, about 26.1 minutes; impurity E, about 27.8 minutes. Inject solution (1) and solution (2). Continue the chromatography of solution (1) for 5 times the retention time of allopurinol.
In the chromatogram obtained with solution (1):
the area of any peak corresponding to impurity A is not greater than the area of the corresponding peak in the chromatogram obtained with solution (3) (0.2%);
the area of any unresolved double peak corresponding to impurities B and C is not greater than the area of the corresponding double peak in the chromatogram obtained with solution (3) (0.2%);
the area of any peaks corresponding to impurity D or impurity E is not greater than the area of the corresponding peak in the chromatogram obtained with solution (3) (0.1%);
the area of any other secondary peak is not greater than the area of the peak due to allopurinol in the chromatogram obtained with solution (2) (0.1%);
the sum of the areas of any other secondary peaks is not greater than 3 times the area of the peak due to allopurinol in the chromatogram obtained with solution (2) (0.3%).
Disregard any peak with an area less than 0.2 times that of the peak due to allopurinol in the chromatogram obtained with solution (2) (0.02%).
Assay
Weigh and powder 20 tablets. Shake a quantity of the powder containing 0.1 g of Allopurinol with 20 mL of 0.05m sodium hydroxide for 20 minutes, add 80 mL of 0.1m hydrochloric acid, shake for 10 minutes, add sufficient 0.1m hydrochloric acid to produce 250 mL, filter and dilute 10 mL of the filtrate to 250 mL with 0.1m hydrochloric acid. Measure the absorbance of the resulting solution at the maximum at 250 nm, Appendix II B, using 0.1m hydrochloric acid in the reference cell. Calculate the content of C5H4N4O taking 563 as the value of A (1%, 1 cm) at the maximum at 250 nm.