Aloxiprin Tablets
Action and use
Salicylate; antipyretic; analgesic; anti-inflammatory.
Definition
Aloxiprin Tablets contain Aloxiprin.
Content of total salicylates
92.5 to 107.5% of the stated amount, calculated as O-acetylsalicylic acid, C9H8O4.
Identification
To 0.5 g of the powdered tablets add 5 mL of hydrochloric acid, boil, cool and filter. Wash the residue with 20 mL of water and combine the filtrate and washings. The resulting solution yields the reaction characteristic of aluminium salts and, after neutralisation with 1m sodium hydroxide, yields reaction A characteristic of salicylates, Appendix VI.
TESTS
Disintegration
Maximum time, 5 minutes, Appendix XII A1.
Free salicylates
To a quantity of the powdered tablets containing the equivalent of 0.6 g of total salicylates add 50 mL of dry ether and shake for 30 minutes. Filter rapidly through fluted filter paper and wash the paper with several portions of dry ether. To the combined filtrate and washings add 10 mL of 1m sodium hydroxide, swirl to mix and evaporate the ether on a water bath. Cool, adjust the pH to between 2.40 and 2.50 with 1m hydrochloric acid and dilute to 100 mL with water. To 20 mL of the resulting solution add 4 mL of iron(iii) chloride solution and dilute to 50 mL with acetate buffer pH 2.45. Allow to stand for 30 minutes, filter, if necessary, through a pair of fluted filter papers and measure the absorbance of the solution at the maximum at 530 nm, Appendix II B, using in the reference cell a solution prepared by diluting 4 mL of iron(iii) chloride solution to 50 mL with acetate buffer pH 2.45. The absorbance is not more than that obtained using 5 mL of a 0.036% w/v solution of salicylic acid diluted to 20 mL with water in place of the solution being examined and beginning at the words ‘add 4 mL of iron(iii) chloride solution ...’ (1.5%, calculated with reference to the content of total salicylates).
Combined salicylate
Not more than 15.0%, calculated as salicylic acid, C7H6O3, with reference to the content of total salicylates when determined by the following method. To a quantity of the finely powdered tablets containing the equivalent of 0.15 g of total salicylates add 40 mL of a 0.5% w/v solution of sodium fluoride in 0.1m hydrochloric acid and shake for 5 minutes. Allow the mixture to stand for 10 minutes, shaking at frequent intervals, extract with six 20-mL quantities of chloroform, filter the combined extracts through anhydrous sodium sulfate, wash with 30 mL of chloroform and dilute to 200 mL with chloroform. Dilute 20 mL of the solution to 100 mL with chloroform and measure the absorbance of the resulting solution at the maximum at 308 nm, Appendix II B. Calculate the content of C7H6O3 taking 293 as the value of A (1%, 1 cm) at the maximum at 308 nm.
Assay
Weigh and finely powder 20 tablets. To a quantity of the powder containing the equivalent of 0.3 g of total salicylates add 50 mL of 1m sodium hydroxide and boil gently for 15 minutes with occasional swirling. Cool, adjust the pH of the mixture to between 2.40 and 2.50 with 1m hydrochloric acid and dilute to 500 mL with water. Filter a portion of the suspension; to 5 mL of the filtrate add 35 mL of acetate buffer pH 2.45 and 4 mL of iron(iii) chloride solution and dilute to 50 mL with water. Allow to stand for 30 minutes and measure the absorbance of the resulting solution at the maximum at 530 nm, Appendix II B, using in the reference cell a solution prepared by diluting 4 mL of iron(iii) chloride solution to 50 mL with acetate buffer pH 2.45. Calculate the content of total salicylates as O-acetylsalicylic acid, C9H8O4, from the absorbance obtained by repeating the procedure using 4 mL of a 0.05% w/v solution of salicylic acid in place of the solution being examined and beginning at the words ‘add 35 mL of acetate buffer pH 2.45 ...’. Each g of salicylic acid is equivalent to 1.305 g of C9H8O4.
Labelling
The quantity of active ingredient is stated both as the amount of Aloxiprin and in terms of the equivalent amount of total salicylates calculated as O-acetylsalicylic acid, C9H8O4.