Piroxicam Gel
Pirixicam Gel contains not less than95.0 per cent and not more than 105.0 per cent of the stated amount of piroxicam, C15H13N3O4S.
Usual strength. 0.5 per cent w/w.
Identification
- In the Assay, the principal peak in the chromatogram obtained with the test solution corresponds to the peak in the chromatogram obtained with the reference solution.
- Determine by thin-layer chromatography (2.4.17), coating the plate withsilica gel GF254.
Test solution. Disperse a quantity of gel containing 10 mg of piroxicam, with 0.1 ml of a saturated solution of sodium chloride until the mixture becomes turbid. Dilute to 5.0 ml with 0.01 M methanolic hydrochloric acid, shake well, centrifuge and use the clear supernatant solution.
Reference solution.A 0.2 per cent w/v solution of piroxicam RS in 0.01 M methanolic hydrochloric acid.
Mobile phase.A mixture of 1 volume of glacial acetic acid 10 volumes of methanol and 80 volumes of ethyl acetate.
Apply to the plate 5 µl of each solution. After development, dry the plate in air and examine under ultraviolet light at 254 nm. The principal spot in the chromatogram obtained with the test solution corresponds to that in the chromatogram obtained with the reference solution.
Tests
pH(2.4.24).7.2 to 8.2 determined in a 10 per cent w/v solution.
2- Pyridylamine.
Determine by liquid chromatography (2.4.14).
Test solution. Disperse a quantity of the gel containing 5 mg of Piroxicam in 5 ml of 0.01 M methanolic hydrochloric acid add 50 ml of the mobile phase and shake vigorously for 30 minutes, dilute to 100.0 ml with mobile phase, mix and filter through a glass fibre membrane filter (1µm).
Reference solution.Dilute 5.0 ml of a 0.0005 per cent w/v solution of 2- pyridylamine in 0.01 M methanolic hydrochloric acid to 100.0ml with the mobile phase.
Chromatographic system
– a stainless steel column 25 cm x 4.6 mm, packed with end-cappedoctylsilanebonded to porous silica(5 µm) (such as zorbax stablebond C8) and stainless steel guard column 10 cm x 4.6 mm, packed with end- capped octylsilane bonded to porous silica (5µm),
– column temperature: 40º,
– mobile phase: a mixture of 15 volumes of methanol, 30 volumes of acetonitrile 55 volumes of a buffer solution of 0.05 M sodium dihydrogenorthoposphatepreviously adjusted to pH to 3.5 with 5 M orthophosphoric acid,
– flow rate: 1 ml per minute,
– spectrophotometer set at 313 nm as an excitation wavelength and at 380 nm as an emission wavelength,
– injection volume:20 µl.
Inject the reference solution and test solution. The area of any peak corresponding to 2- pyridylamine is not more than that of the principal peak in the chromatogram obtained with reference solution (0.5 per cent).
Other tests. Comply with the tests stated under Gel.
Assay. Determine by liquid chromatography (2.4.14).
Use chromatographic system and test solution as described as under 2- pyridylamine except detector.
Reference solution.A 0.1 per cent w/v solution of piroxicam RS in 0.01 M methanolic hydrochloric acid,dissolve with the aid of ultrasound, if necessary. Dilute 5.0 ml of this solution to 100.0 ml with the mobile phase.
Chromatographic system
– spectrophotometer set at 248 nm.
Inject the reference solution.The test is not valid unless 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 C15H13N3O4S in gel.
Storage.Store at a temperature not exceeding 30°. Do not freeze.