Clopidogrel and Aspirin Tablets

Clopidogrel and Aspirin Tablets contain not less than 
90.0 per cent and not more than 110.0 per cent of the stated amount of clopidogrel, C16H16ClNO2S and aspirin, C9H8O₄.

Usual strengths. Clopidogrel 75 mg and Aspirin 75 mg; Clopidogrel 75 mg and Aspirin 150 mg  and Clopidogrel 300 mg and Aspirin 150 mg.

Identification

In the Assay, the principal peaks in the chromatogram obtained with the test solution corresponds to the peak in the chromatogram obtained with reference solution (c).

Tests
Dissolution (2.5.2).

For Clopidogrel

Apparatus. No 1,

Medium. 900 ml of 0.1 M hydrochloric acid,

Speed and time. 50 rpm and 45 minutes. 

Withdraw a suitable volume of the medium and filter.

Determine by liquid chromatography (2.4.14)  

Test solution. Use the filtrate if necessary, with the dissolution medium.

Reference solution. Dissolve a quantity of clopidogrel bisulphate RS in dissolution medium and dilute with the dissolution medium to obtain a solution having a known concentration similar to the expected concentration of  test solution.

Chromatographic system

     –   a stainless steel column 25 cm ´ 4.6 mm, packed with octylsilane bonded to porous silica (5 µm) (Such as Hypersil BDS, C8),

     –   mobile phase: a mixture of 3 volumes of 0.05 M sodium dihydrogen orthophosphate and 1 volume of acetonitrile, adjusted the pH 2.0 with dilute orthophosphoric acid,

     –   flow rate: 1.5 ml per minute,

     –   spectrophotometer set at 210 nm,

     –   injection volume: 20 µl.

The elution order of chromatogram is aspirin and clopidogrel respectively.

Inject the reference solution. The test is not valid unless the column efficiency is not less than 2000 theoretical plates, the tailing factor is not more than 2.0 and the relative standard deviation for replicate injections is not more than 2.0 per cent. 

Inject the reference solution and the test solution

Calculate the content of C₁₆H₁₆ClNO₂S in the tablet.

1 mg of  C₁₆H₁₈ClNO₆S₂ is equivalent to 0.7664 mg of C₁₆H₁₆ClNO₂S_.

1. Not less than 70 per cent of the stated amountof C₁₆H₁₆ClNO₂S_.

For Aspirin

Note: Use freshly prepared reference and test solution.

Apparatus. No 1,

Medium. 900 ml of a buffer solution prepared by dissolving 2.99 g of sodium acetate trihydrate containing 1.66 ml of glacial acetic acid in 1000 ml of water, adjusted to pH 4.5 with sodium hydroxide.

Speed and time. 50 rpm and 60 minutes. 

Withdraw a suitable volume of the medium and filter.

Determine by liquid chromatography (2.4.14)  

Test solution. Use the filtrate if necessary, with the dissolution medium.

Reference solution. Dissolve a quantity of aspirin RS in dissolution medium and dilute with the dissolution medium to obtain a solution having a known concentration similar to the expected concentration of test solution.

Chromatographic system

     –   a stainless steel column 25 cm ´ 4.6 mm, packed with octylsilane bonded to porous silica (5 µm) (Such as Hypersil BDS C8),

     –   mobile phase: a mixture of 3 volumes of 0.05 M sodium dihydrogen orthophosphate and 1 volume of acetonitrile, adjusted the pH 2.0 with dilute orthophosphoric acid,

     –   flow rate: 1.5 ml per minute,

     –   spectrophotometer set at 210 nm,

     –   injection volume: 20 µl.

The elution order is Aspirin and Clopidogrel.

Inject the reference solution. The test is not valid unless the column efficiency is not less than 2000 theoretical plates, the tailing factor is not more than 2.0 and the relative standard deviation for replicate injections is not more than 2.0 per cent.

Inject the reference solution and the test solution.

Calculate the content of C₉H₈O₄ in the tablet.

4. Not less than 70 per cent of the stated amountof C9H8O₄.

Related substances. Determine by liquid chromatography (2.4.14).

For Clopidogrel

Test solution. Disperse a quantity of the powdered tablet containing about 50 mg of clopidogrel into a 50-ml volumetric flask, add 30 ml mobile phase. Sonicate for 15 minutes. Cool and dilute to volume with mobile phase. Filter through 0.45µ syringe filter.

Reference solution (a). A 0.065 per cent w/v solution of clopidogrel bisulphate RS in the mobile phase.

Reference solution (b). Dilute 2.0 ml of reference solution (a) to 200.0 ml with mobile phase.

Chromatographic system

     –   a stainless steel column 25 cm ´ 4.6 mm, packed with octylsilane bonded to porous silica (5 µm) (Such as Hypersil BDS C8),

     –   mobile phase: a mixture of 45 volumes of a buffer solution prepared by dissolving 0.33 g of diammonium hydrogen orthophosphate and 0.2 g of tetrabutylammonium hydrogen sulphate in 100 ml of water, adjusted the pH 7.0 and 55 volumes of acetonitrile,

     –   flow rate: 1 ml per minute,

     –   spectrophotometer set at 210 nm,

     –   Injection volume: 20 µl.

Inject reference solution (a). The test is not valid unless the column efficiency is not less than 2000 theoretical plates, the tailing factor is not more than 2.0 and the relative standard deviation for replicate injections is not more than 5.0 per cent.

Inject reference solution (b) and the test solution. In the chromatogram obtained with the test solution the area of any other secondary peak is not more than the area of the principal peak in the chromatogram obtained with reference solution (b) (0.5 per cent) and the sum of areas of all secondary peaks is not more than twice the area of the principal peak in the chromatogram obtained with the reference solution (b) (1.0 per cent). Ignore any peak with an area less than 0.2 times the area of the principal peak in the chromatogram obtained with the reference solution (b) (0.1 per cent).

For Aspirin

Salicylic acid. Not more than 3.0 per cent.

Determine by liquid chromatography (2.4.14).  

Solvent mixture: a mixture of 99 volumes of acetonitrile and 1 volume of formic acid.

Test solution: Disperse a quantity of the powdered tablet containing about 300 mg of aspirin into a 100-ml volumetric flask, add 70 ml of solvent mixture. Sonicate for 15 minutes. Cool and dilute to volume with mobile phase. Filter through 0.45µ syringe filter.

Reference solution (a). A 0.01 per cent w/v solution of salicylic acid RS in the solvent mixture.

Reference solution (b). A 0.3 per cent w/v solution of aspirin RS and clopidogrel bisulphate RS in the reference solution (a). 

Chromatographic system

     –   a stainless steel column 15 cm ´ 4.6 mm, packed with octadecylsilane bonded to porous silica (5 µm) (Such as Inertsil C18),

     –   autosampler temperature: 5˚,

     –   mobile phase: a mixture of 75 volumes of 0.05M of sodium dihydrogen orthophosphate dihydrate and 25 volumes of acetonitrile, adjusted the pH 2.0 with dilute orthophosphoric acid,

     –   flow rate: 1.5 ml per minute,

     –   spectrophotometer set at 280 nm,

     –   Injection volume: 20 µl.

 

The elution order of chromatogram is aspirin, salicylic acid and clopidogrel bisulphate respectively.

Inject reference solution (a) and (b). The test is not valid unless the resolution between salicylic acid and aspirin

is not less than 2.0 and salicylic acid and clopidogrel is not less than 1.5 obtained from reference solution (b).

The column efficiency is not less than 2000 theoretical plates, the tailing factor is not more than 2.0 and the

relative standard deviation for replicate injections is not more than 2.0 per cent obtained from reference solution

(a).

Assay. Determine by liquid chromatography (2.4.14).

Test solution. Weigh and powder 20 tablets. Weigh a quantity of powder containing about 100 mg of Clopidogrel  in 250-ml volumetric flask, add sufficient amount of methanol. Sonicate for 15 minutes. Cool and dilute to volume with methanol, mix and filter through 0.45µ syringe filter. Dilute 5.0 ml of the filtrate to 25.0 ml with mobile phase and mix.

Reference solution (a). A 0.08 per cent w/v solution of clopidogrel bisulphate RS in methanol.

Reference solution (b). A 0.08 per cent w/v solution of aspirin RS in methanol.

Reference solution (c). Dilute reference solution (a) and reference solution (b) with mobile phase to obtain a solution having similar concentration to the test solution.

Chromatographic system

     –   a stainless steel column 25 cm x 4.6 mm, packed with octylsilane bonded to porous silica (5 µm) (Such as Hypersil BDS C8),

     –   mobile phase:            A. a mixture of 3 volumes of 0.05 M sodium dihydrogen orthophosphate and 1 volume of acetonitrile, adjusted the pH 2.0 with dilute orthophosphoric acid,

     –   flow rate: 1.5 ml per minute,

     –   spectrophotometer set at 210 nm,

     –   injection volume: 20 µl.

Inject reference solution (c). The test is not valid unless the column efficiency is not less than 2000 theoretical plates, the tailing factor is not more than 2.0 and the relative standard deviation for replicate injections is not more than 2.0 per cent.

 

Inject reference solution (c) and the test solution.

Calculate the contents of C16H16ClNO2S and C9H8O₄.

Storage. Store in a cool and dry place.