Cephalexin for Oral Suspension
Cephalexin for Oral Suspension is a dry mixture of Cephalexin and one or more suitable buffers, colors, diluents, and flavors. It contains the equivalent of NLT 90.0% and NMT 120.0% of the labeled amount of C16H17N3O4S per mL when constituted as directed in the labeling.
• The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
Mobile phase: 0.985 g/L of sodium 1-pentanesulfonate in a mixture of acetonitrile, methanol, triethylamine, and water (20:10:3:170), adjusted 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: Mix 10.0 mL of Standard stock solution with 15.0 mL of Mobile phase.
Sample stock solution: Nominally equivalent to 1 mg/mL of cephalexin from Oral Suspension, constituted as directed in the labeling, freshly mixed and free from air bubbles. Sonicate, if necessary, to assure complete dissolution of the cephalexin. Filter, if necessary, to obtain a clear solution.
Sample solution: Mix 10.0 mL of Sample stock solution and 15.0 mL of Mobile phase.
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
Sample: Standard solution
Relative standard deviation: NMT 2.0%
Samples: Standard solution and Sample solution
Calculate the percentage of cephalexin (C16H17N3O4S) in each mL of the constituted Suspension taken:
Result = (rU/rS) × (CS/CU) × P × F × 100
Acceptance criteria: 90.0%120.0%
• Uniformity of Dosage Units 905 For solid packaged in single-unit containers: meets the requirements
• Deliverable Volume 698: Meets the requirements
• pH 791: 3.06.0, constituted as directed in the labeling
• Packaging and Storage: Preserve in tight containers.
• USP Reference Standards 11
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USP35NF30 Page 2587Pharmacopeial Forum: Volume No. 36(1) Page 45