Cephalexin Tablets
» Cephalexin Tablets are prepared from Cephalexin or Cephalexin Hydrochloride. They contain the equivalent of not less than 90.0 percent and not more than 120.0 percent of the labeled amount of cephalexin (C16H17N3O4S).
Packaging and storage— Preserve in tight containers.
Labeling— The label states whether the Tablets contain Cephalexin or Cephalexin Hydrochloride.
Identification— Mix a quantity of finely powdered Tablets with water to obtain a concentration of about 3 mg of cephalexin per mL, and filter (test solution). Proceed as directed in the Identification test under Cephalexin Capsules, beginning with “Place a suitable thin-layer chromatographic plate”: the RF value of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Dissolution 711
For cephalexin
Medium: water; 900 mL.
Apparatus 1— Use 40-mesh cloth and 100 rpm.
Time: 30 minutes.
Procedure— Determine the amount of C16H17N3O4S dissolved from the UV absorbances at the wavelength of maximum absorbance at about 262 nm of a filtered portion of the solution under test, suitably diluted with Dissolution Medium, if necessary, to a concentration of about 20 µg per mL, in comparison with a Standard solution having a known concentration of USP Cephalexin RS in the same medium.
Tolerances— Not less than 80% (Q) of the labeled amount of C16H17N3O4S is dissolved in 30 minutes.
For cephalexin hydrochloride
Medium and Procedure—Proceed as directed under For cephalexin.
Apparatus 1— Use 10-mesh cloth and 150 rpm.
Time: 45 minutes.
Tolerances— Not less than 75% (Q) of the labeled amount of C16H17N3O4S is dissolved in 45 minutes.
Uniformity of dosage units 905: meet the requirements.
Water, Method I 921: not more than 9.0% where Tablets contain Cephalexin; not more than 8.0% where Tablets contain Cephalexin Hydrochloride.
Mobile phase , Internal standard solution, Standard preparation, and Chromatographic system—Prepare as directed in the Assay under Cephalexin.
Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed quantity of the powder, equivalent to about 500 mg of cephalexin, to a 500-mL volumetric flask, add water to volume, and mix. Sonicate, if necessary, to assure complete dissolution of the cephalexin. Filter, if necessary, to obtain a clear solution. Transfer 10.0 mL of this solution to a 50-mL, glass-stoppered flask, add 15.0 mL of Internal standard solution, mix, and filter.
Procedure— Proceed as directed for Procedure in the Assay under Cephalexin. Calculate the quantity, in mg, of C16H17N3O4S in the portion of Tablets taken by the formula:
0.5CP(RU / RS)
in which the terms are as defined therein.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Ahalya Wise, M.S.
(MDANT05) Monograph Development-Antibiotics
Reference Standards Lili Wang, Technical Services Scientist
711 Margareth R.C. Marques, Ph.D.
Senior Scientist
(BPC05) Biopharmaceutics05
USP32–NF27 Page 1872
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.