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 not less than 90.0percent and not more than 120.0percent of the labeled amount of C16H17N3O4Sper mLwhen constituted as directed in the labeling.
Packaging and storage— Preserve in tight containers.
Identification— Constitute 1container of Cephalexin for Oral Suspension as directed in the labeling.Mix a portion of the resulting suspension with water to obtain a concentration of about 3mg of cephalexin per mL,and filter (test solution).Proceed as directed in the Identificationtest under Cephalexin Capsules,beginning with “Place a suitable thin-layer chromatographic plate”:the RFvalue of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Uniformity of dosage units á905ñ—
FORSOLID PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.
Deliverable volume á698ñ: meets the requirements.
pHá791ñ: between 3.0and 6.0,in the suspension constituted as directed in the labeling.
Water,Method Iá921ñ: not more than 2.0%.
Assay—
Mobile phase— Prepare as directed in the Assayunder Cephalexin.
Standard preparation— Dissolve an accurately weighed quantity of USP Cephalexin RSquantitatively in water to obtain a stock solution having a known concentration of about 1mg per mL.Transfer 10.0mLof this stock solution to a 50-mL,glass-stoppered flask,add 15.0mLof Mobile phase,and mix.
Resolution solution— Transfer 300mg of 1-hydroxybenzotriazole to a 1000-mLvolumetric flask,dissolve in 10mLof methanol,dilute with Mobile phaseto volume,and mix.To 15.0mLof this solution add 10.0mLof the stock solution used to prepare the Standard preparation.
Assay preparation— Constitute Cephalexin for Oral Suspension as directed in the labeling.Transfer an accurately measured volume of the suspension so obtained,freshly mixed and free from air bubbles,equivalent to about 250mg of cephalexin,to a 250-mLvolumetric flask,dilute with water to volume,and mix.Sonicate,if necessary,to assure complete dissolution of the cephalexin.Filter,if necessary,to obtain a clear solution.Transfer 10.0mLof this solution to a 50-mLglass-stoppered flask,add 15.0mLof Mobile phase,mix,and filter.
Chromatographic system (see Chromatography á621ñ)—Proceed as directed for Chromatographic systemin the Assayunder Cephalexin,except to chromatograph the Resolution solutionto confirm that the resolution,R,between the 1-hydroxybenzotriazole peak and the cephalexin peak is not less than 5.The relative retention times are about 0.35for 1-hydroxybenzotriazole and 1.0for cephalexin.
Procedure— Proceed as directed for Procedurein the Assayunder Cephalexin.Calculate the quantity,in mg,of C16H17N3O4Sin each mLof the constituted Suspension taken by the formula:
0.25(CP/V)(rU/rS),
in which Vis the volume,in mL,of the constituted Suspension taken,rUand rSare the cephalexin peak responses obtained from the Assay preparationand the Standard preparation,respectively,and the other terms are as defined therein.
Auxiliary Information— Staff Liaison:William W.Wright,Ph.D.,Scientific Fellow
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 415
Phone Number:1-301-816-8335