Cephalexin Tablets
DEFINITION
Cephalexin Tablets are prepared from Cephalexin or Cephalexin Hydrochloride. They contain the equivalent of NLT 90.0% and NMT 120.0% of the labeled amount of cephalexin (C16H17N3O4S).
IDENTIFICATION
• The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
ASSAY
• Procedure
Mobile phase:
0.985 g/L of sodium 1-pentanesulfonate in a mixture of acetonitrile, methanol, triethylamine, and water (20:10:3:170). Adjust with phosphoric acid to a pH of 3.0 ± 0.1.
Standard stock solution:
1 mg/mL of USP Cephalexin RS in water
Standard solution:
0.4 mg/mL of cephalexin in Mobile phase from Standard stock solution
Sample stock solution:
Equivalent to 1 mg/mL of cephalexin from combined contents of powdered Tablets (NLT 20) in water. Sonicate, if necessary, to assure complete dissolution of the cephalexin. Filter, if necessary, to obtain a clear solution.
Sample solution:
0.4 mg/mL of cephalexin in Mobile phase from Sample stock solution
Chromatographic system
Mode:
LC
Detector:
UV 254 nm
Column:
4.6-mm × 25-cm; packing L1 of low acidity
Flow rate:
1.5 mL/min
Injection size:
20 µL
System suitability
Sample:
Standard solution
Suitability requirements
Relative standard deviation:
NMT 2.0%
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of cephalexin (C16H17N3O4S) in the portion of Tablets taken:
Result = (rU/rS) × (CS/CU) × P × F × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of USP Cephalexin RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of cephalexin in the Sample solution (mg/mL) |
| P | = | = potency of cephalexin in USP Cephalexin RS (µg/mg) |
| F | = | = conversion factor, 0.001 mg/µg |
Acceptance criteria:
90.0%–120.0%
PERFORMANCE TESTS
• Dissolution 
711
711
For Cephalexin
Medium:
Water; 900 mL
Apparatus 1:
Use 40-mesh cloth and 100 rpm
Time:
30 min
Standard solution:
20 µg/mL of USP Cephalexin RS in Medium
Sample solution:
Pass a portion of the solution under test through a suitable filter. Dilute, if necessary, with Medium to a concentration that is similar to the Standard solution.
Spectrometric conditions
Mode:
UV
Analytical wavelength:
262 nm
Analysis
Samples:
Standard solution and Sample solution
Tolerances:
NLT 80% (Q) of the labeled amount of cephalexin (C16H17N3O4S) is dissolved.
For Cephalexin hydrochloride
Medium, Standard solution, Sample solution, Spectrometric conditions, and Analysis:
Proceed as directed For Cephalexin.
Apparatus 1:
Use 10-mesh cloth and 150 rpm.
Time:
45 min
Tolerances:
NLT 75% (Q) of the labeled amount of cephalexin (C16H17N3O4S) is dissolved.
• Uniformity of Dosage Units 905:
Meet the requirements
905:
Meet the requirements
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers.
• Labeling:
The label states whether the Tablets contain Cephalexin or Cephalexin Hydrochloride.
• USP Reference Standards 11
11
USP Cephalexin RS 
') + '&img=../../images/v35300/cas-23325-78-2.gif',600,500);)
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Ahalya Wise, M.S.
Senior Scientific Liaison 1-301-816-8161 |
(SM12010) Monographs - Small Molecules 1 |
| 711 |
Margareth R.C. Marques, Ph.D.
Senior Scientific Liaison 1-301-816-8106 |
(GCDF2010) General Chapters - Dosage Forms |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 2587
Pharmacopeial Forum: Volume No. 36(1) Page 46