Cefalexin Tablets
Action and use
Cephalosporin antibacterial.
Definition
Cefalexin Tablets contain Cefalexin Monohydrate.
Content of anhydrous cefalexin, C16H17N3O4S
92.5 to 110.0% of the stated amount.
Identification
Remove any coating. Shake a quantity of the powdered tablet cores containing the equivalent of 0.5 g of anhydrous cefalexin with 1 mL of water and 1.4 mL of 1m hydrochloric acid, add 0.1 g of activated charcoal, shake, filter and wash the filter with 1 mL of water. Add slowly to the filtrate a saturated solution of sodium acetate until precipitation occurs. Add 5 mL of methanol, filter and wash the precipitate with two 1-mL quantities of methanol. The residue, after drying at a pressure not exceeding 0.7 kPa, complies with the following tests.
15 volumes of acetone and 85 volumes of a 15.4% w/v solution of ammonium acetate, previously adjusted to pH 6.2 with 5m acetic acid.
The test is not valid unless the chromatogram obtained with solution (3) shows two clearly separated spots.
The principal spot in the chromatogram obtained with solution (1) is similar in position and size to that in the chromatogram obtained with solution (2).
Tests
Disintegration
Maximum time, 30 minutes, Appendix XII A1.
Related substances
Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions in 2m hydrochloric acid.
3 volumes of acetone, 80 volumes of a 7.2% w/v solution of disodium hydrogen orthophosphate and 120 volumes of a 2.1% w/v solution of citric acid.
The test is not valid unless the chromatogram obtained with solution (5) shows three clearly separated spots.
In the chromatogram obtained with solution (1):
any spot corresponding to 7-aminodesacetoxycephalosporanic acid is not more intense than the spot in the chromatogram obtained with solution (3) (1%);
any spot corresponding to dl-phenylglycine is not more intense than the spot in the chromatogram obtained with solution (4) (1%);
any other secondary spot is not more intense than the spot in the chromatogram obtained with solution (2) (1%).
Assay
Weigh and powder 20 tablets. Carry out the method for liquid chromatography, Appendix III D, using the following solutions in water.
2 volumes of methanol, 5 volumes of acetonitrile, 10 volumes of a 1.36% w/v solution of potassium dihydrogen orthophosphate and 83 volumes of water.
The Assay is not valid unless, in the chromatogram obtained with solution (3), the resolution factor between the peaks corresponding to cefalexin and cefradine is at least 4.0; if necessary, adjust the acetonitrile content of the mobile phase.
Inject solution (2) six times. The Assay is not valid unless the relative standard deviation of the area of the principal peak is at most 1.0%.
Calculate the content of C16H17N3O4S in the tablets using the declared content of C16H17N3O4S in cefalexin BPCRS.
Storage
Cefalexin Tablets should be stored at a temperature not exceeding 30°.
Labelling
The quantity of active ingredient is stated in terms of the equivalent amount of anhydrous cefalexin.