BP 2025 (Ph. Eur. 11.6 update)
Action and use
Inhibitor of ADP-mediated platelet aggregation; antiplatelet.
DEFINITION
Clopidogrel Hydrogen Sulfate Tablets contain Clopidogrel Hydrogen Sulfate.
The tablets comply with the requirements stated under Tablets and with the following requirements.
Content of clopidogrel, C16H16ClNO2S
95.0 to 105.0% of the stated amount.
IDENTIFICATION
Shake a quantity of powdered tablets containing the equivalent of 50 mg of clopidogrel with 10 mL of anhydrous ethanol, filter and evaporate to dryness. The infrared absorption spectrum of the dried residue, Appendix II A, is concordant with the reference spectrum of clopidogrel hydrogen sulfate (RS 516).
TESTS
Dissolution
Comply with the dissolution test for tablets and capsules, Appendix XII B1.
TEST CONDITIONS
(a) Use Apparatus 2, rotating the paddle at 50 revolutions per minute.
(b) Use 900 mL of a solution containing 12 volumes of 0.1M hydrochloric acid and 88 volumes of 0.657% w/v of potassium chloride, at a temperature of 37°, as the medium.
PROCEDURE
(1) After 30 minutes withdraw a sample of the medium and measure the absorbance at 240 nm of the filtered sample, suitably diluted with the dissolution medium, if necessary, to produce a solution expected to contain the equivalent of 0.008% w/v of clopidogrel, Appendix II B, using dissolution medium in the reference cell.
(2) Measure the absorbance at 240 nm of a 0.011% w/v solution of clopidogrel hydrogen sulfate BPCRS in the dissolution medium using dissolution medium in the reference cell.
DETERMINATION OF CONTENT
Calculate the total content of clopidogrel, C16H16ClNO2S, in the medium from the absorbances obtained and using the declared content of C16H16ClNO2S,H2SO4 in clopidogrel hydrogen sulfate BPCRS.
Each mg of C16H16ClNO2S,H2SO4 is equivalent to 0.7664 mg of C16H16ClNO2S.
LIMITS
The amount of clopidogrel released is not less than 80% (Q) of the stated amount.
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) To a quantity of powdered tablets containing the equivalent of 75 mg of clopidogrel, add 5 mL of methanol and mix with the aid of ultrasound. Add 100 mL of the mobile phase and shake. Dilute to produce 200 mL with the mobile phase and filter (a 0.45-μm PTFE filter is suitable).
(2) Dilute 1 volume of solution (1) to 100 volumes with the mobile phase.
(3) 0.375% w/v of clopidogrel for system suitability EPCRS and 0.00375% w/v of clopidogrel impurity A EPCRS in methanol. Dilute 1 volume to 10 volumes with the mobile phase.
(4) Dilute 1 volume of solution (2) to 10 volumes with the mobile phase.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (15 cm × 4.6 mm) packed with protein derivative of silica gel for chiral separation (5 μm) (Ultron ES-OVM is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 220 nm.
(f) Inject 10 μL of each solution.
(g) Allow the chromatography to proceed for 3 times the retention time of clopidogrel.
MOBILE PHASE
25 volumes of acetonitrile R1 and 75 volumes of 0.01M potassium dihydrogen orthophosphate.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution between the peaks due to impurity B (enantiomer 1) and clopidogrel is at least 1.5.
CALCULATION OF IMPURITIES
For each impurity, use the concentration of clopidogrel in solution (2).
For the reporting threshold, use the concentration of clopidogrel in solution (4). Apply the reporting threshold to the sum of impurity B enantiomers 1 and 2.
For peak identification, use solution (3).
Clopidogrel retention time: about 6 minutes.
Relative retention: impurity A, about 0.5; impurity B (enantiomer 1), about 0.8; impurity B (enantiomer 2), about 1.2; impurity C, about 2.0.
LIMITS
— impurity C: not more than 1.5%;
— impurity A: not more than 1.2%;
— impurity B (sum of enantiomers 1 and 2): not more than 0.3%;
— unspecified impurities: for each impurity, not more than 0.2%;
— total impurities: not more than 2.5%;
— reporting threshold: 0.1%.
ASSAY
Weigh and powder 20 tablets. Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) To a quantity of powdered tablets containing the equivalent of 75 mg of clopidogrel, add 50 mL of methanol and mix with the aid of ultrasound. Dilute to produce 100 mL with methanol. Dilute 1 volume to 20 volumes with the mobile phase and filter (a 0.45-μm glass microfibre filter is suitable).
(2) 0.1% w/v of clopidogrel hydrogen sulfate BPCRS in methanol. Dilute 1 volume to 20 volumes with the mobile phase.
(3) 0.375% w/v of clopidogrel for system suitability EPCRS and 0.00375% w/v of clopidogrel impurity A EPCRS in methanol. Dilute 1 volume to 10 volumes with the mobile phase.
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions 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 impurity B (enantiomer 1) and clopidogrel is at least 1.5.
DETERMINATION OF CONTENT
Calculate the content of clopidogrel, C16H16ClNO2S, in the tablets from the chromatograms obtained and using the declared content of C16H16ClNO2S,H2SO4 in clopidogrel hydrogen sulfate BPCRS.
Each mg of C16H16ClNO2S,H2SO4 is equivalent to 0.7664 mg of C16H16ClNO2S
LABELLING
The quantity of active ingredient is stated in terms of the equivalent amount of clopidogrel.
IMPURITIES
The impurities limited by the requirements of this monograph include impurities A, B and C listed under Clopidogrel Hydrogen Sulfate.
