Edition: BP 2025 (Ph. Eur. 11.6 update)
Aspirin Gastro-resistant Tablets
General Notices
Gastro-resistant Aspirin Tablets
Action and use
Salicylate; non-selective cyclo-oxygenase inhibitor; antipyretic; analgesic; anti-inflammatory and antiplatelet.
DEFINITION
Aspirin Gastro-resistant Tablets contain Aspirin. They are made gastro-resistant by enteric-coating or by other means. The tablets comply with the requirements stated under Tablets and with the following requirements.
Content of aspirin, C9H8O4
95.0 to 105.0% of the stated amount.
IDENTIFICATION
Shake a quantity of the powdered tablets containing 0.5 g of Aspirin with 20 mL of absolute ethanol, filter (Whatman GF/C is suitable), evaporate the filtrate and dry the residue at 60° for 1 hour. The infrared absorption spectrum of the residue, is concordant with the reference spectrum of aspirin (RS 483).
TESTS
Dissolution
Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules, Appendix XII B1.
TEST CONDITIONS
First stage
(a) Use Apparatus 1, rotating the basket at 100 revolutions per minute.
(b) Use 900 mL of 0.1M hydrochloric acid, at a temperature of 37°, as the medium.
PROCEDURE
(1) After 2 hours, withdraw a sample of the medium, filter and measure the absorbance of the filtrate, Appendix II B, at 276 nm using 0.1M hydrochloric acid in the reference cell.
(2) Measure the absorbance of a suitable solution of aspirin BPCRS in 0.1M hydrochloric acid.
DETERMINATION OF CONTENT
Calculate the total content of aspirin, C9H8O4, in the medium using the declared content of C9H8O4 in aspirin BPCRS. The amount of aspirin released is not more than 5% of the stated amount.
Final stage
(a) Use Apparatus 1, rotating the basket at 100 revolutions per minute.
(b) Replace the 0.1M hydrochloric acid in the vessel with 900 mL of mixed phosphate buffer pH 6.8, previously held at 36.5° to 37.5°.
PROCEDURE
(1) After 45 minutes, withdraw a sample of the medium and filter. Immediately measure the absorbance of the filtrate, Appendix II B, diluted with the dissolution medium, if necessary, at 265 nm using dissolution medium in the reference cell. (2) Measure the absorbance of a suitable solution of aspirin BPCRS in the dissolution medium.
DETERMINATION OF CONTENT
Calculate the total content of aspirin, C9H8O4, in the medium using the declared content of C9H8O4 in aspirin BPCRS.
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions prepared immediately before use.
(1) Mix with the aid of ultrasound for 15 minutes, a quantity of the powdered tablets containing 0.10 g of Aspirin with 40 mL of acetonitrile, allow to cool, dilute to 100 mL with water and filter through a 0.45-µm PTFE filter. (2) Dilute 1 volume of solution (1) to 50 volumes and further dilute 1 volume of the resulting solution to 10 volumes with the mobile phase.
(3) 0.001% w/v of salicylic acid (impurity C) in the mobile phase.
(4) 0.1% w/v of aspirin impurity standard BPCRS in the mobile phase.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with octadecylsilyl silica gel for chromatography (5 µm) (Kromasil C18 is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1.0 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 237 nm.
(f) Inject 20 µL of each solution.
(g) Allow the chromatography to proceed for 1.2 times the retention time of impurity F.
MOBILE PHASE
2 volumes of orthophosphoric acid, 400 volumes of acetonitrile and 600 volumes of water.
When the chromatograms are recorded under the prescribed conditions, the retentions relative to aspirin (retention time about 5 minutes) are: impurity A, about 0.6; impurity B, about 0.7; impurity C, about 1.4; impurity D, about 2.9; impurity E, about 4.3 and impurity F, about 8.0.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (4), the resolution between the peaks due to aspirin and impurity C is at least 6.0.
The test is not valid unless, in the chromatogram obtained with solution (4), the resolution between the peaks due to impurities A and B is at least 2.5.
LIMITS
Use the chromatogram supplied with aspirin impurity standard BPCRS and the chromatogram obtained with solution (4) to identify the peaks due to due to impurities A, B, C and F. Multiply the area of any peak corresponding to impurity B by a correction factor of 0.7.
In the chromatogram obtained with solution (1):
the area of any peak corresponding to impurity C is not greater than three times the area of the principal peak in the chromatogram obtained with solution (3) (3%);
the area of any peak corresponding to impurities A, B, D, E or F is not greater than 0.15 times the area of the principal peak in the chromatogram obtained with solution (3) (0.15% of each);
the area of any other secondary peak is not greater than half the area of the principal peak in the chromatogram obtained with solution (2) (0.10%);
the sum of the areas of any other secondary peaks is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (0.2%).
Disregard any peak with an area less than 0.25 times the area of the principal peak in the chromatogram obtained with solution (2) (0.05%).
ASSAY
Weigh and powder 20 tablets. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) Mix with the aid of ultrasound for 15 minutes, a quantity of the powdered tablets containing 60 mg of Aspirin with 40 mL of acetonitrile, allow to cool, dilute to 100 mL with water and filter through a 0.45-µm PTFE filter. (2) 0.06% w/v of aspirin BPCRS in the mobile phase.
(3) 0.1% w/v of aspirin impurity standard BPCRS in the mobile phase.
CHROMATOGRAPHIC CONDITIONS
The chromatographic procedure described under Related substances may be used.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the peaks due to aspirin and impurity C is at least 6.0.
DETERMINATION OF CONTENT
Calculate the content of C9H8O4 in the tablets from the chromatograms obtained using the declared content of C9H8O4 in aspirin BPCRS.
STORAGE
Aspirin Gastro-resistant Tablets should be protected from moisture.
LABELLING
The label states that the tablets contain Aspirin, unless this word appears in the name of the tablets (this requirement does not apply in countries where exclusive proprietary rights in the name Aspirin are claimed).
IMPURITIES
The impurities limited by the requirements of this monograph include those listed under Aspirin.
