Sulfasalazine Gastro-resistant Tablets
Sulfasalazine Gastro-resistant Tablets contain not less than 95.0 per cent and not more than 105.0 per cent of the stated amount of sulfasalazine, C18H14N4O5S. They are made gastro-resistant by enteric-coating or by any other means.
Usual strength. 500 mg.
Identification
- To a quantity of the powdered tablets containing 0.2 g of Sulfasalazine, add 100 ml ofmethanol, shake thoroughly and filter. Evaporate the filtrate to dryness at about 35oand dry the resulting precipitate at a pressure of 2kPa for 1 hour. The residue complies with the following test.
Determine by infrared absorption spectrophotometry (2.4.6). Compare the spectrum with that obtained with sulfasalazine RS or with the reference spectrum of sulfasalazine.
- In the test of Related substances, the principal peak in the chromatogram obtained with test solution corresponds to the peak in the chromatogram obtained with reference solution (c).
Tests
Dissolution (2.5.2).
- Apparatus No.1,
Medium. 1000 ml of 0.1 M hydrochloric acid,
Speed and time. 100 rpm and 120 minutes.
Withdraw a suitable volume of the medium and filter. Measure the absorbance of the filtered solution immediately, suitably diluted with the dissolution medium, if necessary, at the maximum at about 406 nm (2.4.7). Calculate the content of C18H14N4O5S in the medium from the absorbance obtained from a 0.005 per cent w/v solution of sulfasalazine RS, prepared by dissolving in 0.1 M hydrochloric acid.
Complies with the acceptance criteria given under acid stage.
- Apparatus No. 1,
Medium. 900 ml of a phosphate buffer prepared by dissolving 6.8 g of potassium dihydrogen orthophosphate and 1.66 g of sodium hydroxide in sufficient water to produce 1000 ml and adjusting the pH to 7.5 with 5M sodium hydroxide if necessary.
Speed and time. 50 rpm and 45 minutes.
Withdraw a suitable volume of the medium and filter. Measure the absorbance of the filtered solution, suitably diluted with dissolution medium if necessary, at the maximum at about 406 nm (2.4.7). Calculate the content of C18H14N4O5S in the medium from the absorbance obtained from a 0.005 per cent w/v solution of sulfasalazine RS in the same medium.
- Not less than 75 per cent of the stated amount ofC18H14N4O5S.**
Related substances. Determine by liquid chromatography (2.4.14).
Test solution. Shake a quantity of the powdered tablets containing 0.1 g of sulfasalazine with 100.0 ml of 0.1M ammonia for 30 minutes, centrifuge and use the supernatant liquid.
Reference solution (a). Dilute 1.0 ml of the test solution to 100.0 ml with 0.1M ammonia.
Reference solution (b). A solution containing 0.001per cent w/v of sulfasalazine derivative for resolution RS in reference solution (a).
Reference solution (c). A solution containing 0.001per cent w/v of sulfasalazine RS in 0.1M ammonia.
Reference solution (d). Dilute 1 ml of reference solution (a) to 20 ml with 0.1M ammonia.
Chromatographic system
– a stainless steel column 25 cm x 4.6 mm, packed with octadecylsilane bonded to porous silica (5 µm) (Such as Nucleosil C18),
– mobile phase A. A solution containing 0.013per cent w/v of sodium dihydrogen orthophosphate and 0.25per cent w/v of sodium acetate adjusted to pH 4.8 with glacial acetic acid;
- B. a mixture of 80 volumes of methanol and 20 volumes of mobile phase A,
– a gradient programme using the condition given below,
– flow rate: 1.0 ml per minute,
– spectrophotometer set at 320 nm,
– injection volume: 20 µl.
Time Mobile phase A Mobile phase B
(in min.) (per cent v/v) (per cent v/v)
0 60 40
15 45 55
25 45 55
60 0 100
65 0 100
67 60 40
77 60 40
Name Relative
retention time
Sulfasalazine impurity H8 0.16
Sulfasalazine impurity I9 0.28
Sulfasalazine impurity C3 0.80
Sulfasalazine impurity F6 0.85
Sulfasalazine 1.00
Sulfasalazine impurity G7 1.39
Sulfasalazine impurity E5 1.63
Sulfasalazine impurity B2 1.85
Sulfasalazine impurity D4 1.90
Sulfasalazine impurity A1 2.00
1 4,4′-[(4-hydroxy-1,3-phenylene)bis(diazenediyl)]bis[N-(pyridin-2-yl)benzenesulfonamide],
22-hydroxy-3,5-bis[2-[4-(pyridin-2-ylsulfamoyl)phenyl]diazenyl]benzoic acid,
32-hydroxy-5-[2-[4-(2-iminopyridin-1(2H)-yl)phenyl]diazenyl]benzoic acid,
44-[2-(2-hydroxyphenyl)diazenyl]-N-(pyridin-2-yl)benzenesulfonamide,
52-hydroxy-4′-(pyridin-2-ylsulfamoyl)-5-[2-[4-(pyridin-2-ylsulfamoyl)phenyl]diazenyl]biphenyl-3-carboxylic acid,
62-hydroxy-3-[2-[4-(pyridin-2-ylsulfamoyl)phenyl]diazenyl]benzoic acid,
75-[2-[4′,5-bis(pyridin-2-ylsulfamoyl)biphenyl-2-yl]diazenyl]-2-hydroxybenzoic acid,
82-hydroxybenzenecarboxylic acid (salicylic acid),
92-hydroxy-5-[2-(4-sulfophenyl)diazenyl]benzoic acid,
Inject reference solution (b). The test is not valid unless the resolution between the peaks due to sulfasalazine and its derivatives is not less than 3.0.
Inject reference solution (a), (d) and the test solution. In the chromatogram obtained with the test solution, the area of any secondary peak is not more than the area of the principal peak in the chromatogram obtained with reference solution (a) (1.0 per cent). The sum of areas of all the secondary peaks is not more than 4 times the area of the principal peak in the chromatogram obtained with reference solution (a) (4.0 per cent). Ignore any peak with an area less than the area of the principal peak in the chromatogram obtained with reference solution (d) (0.05 per cent). And also ignore any peak with a retention time less than 6 min (due to impurities H and J).
Salicylic acid and Sulfapyridine. Determine by liquid chromatography (2.4.14).
Test solution. Shake a quantity of the powdered tablets containing 0.1 g of sulfasalazine with 100.0 ml of 0.1M ammonia for 30 minutes, centrifuge and use the supernatant liquid.
Reference solution. A solution containing 0.05 per cent w/v of salicylic acid and 0.05 per cent w/v of sulfapyridine RS (H2N-R: 4-amino-N-(pyridin-2-yl)benzenesulfonamide). in 0.1M ammonia and dilute 1.0 ml of this solution to 50.0 ml with 0.1M ammonia.
Chromatographic system
– a stainless steel column 25 cm × 4.6 mm, packed with octadecylsilane bonded to porous silica (5 µm) (Such as Nucleosil C18),
– mobile phase: a mixture of 30 volumes of Mobile phase B and 70 volumes of mobile phase A (described under related substances),
– flow rate: 1 ml per minute,
– spectrophotometer set at 300 nm,
– injection volume: 20 µl.
Inject the reference solution. The test is not valid unless the resolution between the peaks corresponding to sulfasalazine impurity H and sulfasalazine impurity J is not less than 2.0.
Inject the reference solution and the test solution. In the chromatogram obtained with the test solution, the area of any peak due to impurities salicylic acid and sulfapyridine is not more than 0.5 times the areas of the principal peak in the chromatogram obtained with reference solution (a) (0.5 per cent of each).
Other tests. Comply with the tests stated under Tablets.
Assay.
Weigh and powder 20 tablets. Disperse a quantity of the powder containing 150 mg in 100.0 ml of 0.1 M sodium hydroxide. Dilute 5.0 ml of this solution with 750 ml of water add 20 ml of 0.1M acetic acid and dilute to 1000 ml with water. Measure the absorbance of the resulting solution at the maximum at about 359 nm (2.4.7) using sulfasalazine RS prepared as the test solution.
Calculate the content of C18H14N4O5S.