Packaging and storage—
Preserve in tight containers.
Labeling—
The quantity of cephradine stated in the labeling is in terms of anhydrous cephradine (C16H19N3O4S).
Identification—
Mix the contents of 1 Capsule with water to obtain a solution having a concentration of about 3 mg of cephradine per mL, and filter
(test solution). Place a suitable thin-layer chromatographic plate (see
Chromatography 
621
) coated with a 0.25-mm layer of binder-free silica gel in a chamber containing a mixture of
n-hexane and tetradecane (95:5) to a depth of about 1 cm, allow the solvent front to move the length of the plate, remove the plate from the chamber, and allow the solvent to evaporate. On this plate apply 10 µL each of the test solution and a Standard solution containing 3 mg of
USP Cephradine RS per mL. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of 0.1
M citric acid, 0.1
M dibasic sodium phosphate, and a 1 in 15 solution of ninhydrin in acetone (60:40:1.5) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, dry the plate for 10 minutes at 110
, and examine the chromatogram: the
RF value of the principal spot obtained from the
test solution corresponds to that obtained from the
Standard solution.
Dissolution 711—
Medium:
0.12 N hydrochloric acid; 900 mL.
Apparatus 1:
100 rpm.
Time:
45 minutes.
Procedure—
Determine the amount of C
16H
19N
3O
4S dissolved from UV absorbances at the wavelength of maximum absorbance at about 255 nm of filtered portions of the solution under test, suitably diluted with
Dissolution Medium, if necessary, in comparison with a Standard solution having a known concentration of
USP Cephradine RS in the same medium.
Tolerances—
Not less than 75% (Q) of the labeled amount of C16H19N3O4S is dissolved in 45 minutes.
Loss on drying 731—
Dry about 100 mg, accurately weighed, of the mixed contents of 4 Capsules in a capillary-stoppered bottle in vacuum at a pressure not exceeding 5 mm of mercury at 60
for 3 hours: the Capsule contents lose not more than 7.0% of their weight.
Assay—
Mobile phase, Standard preparation, Resolution solution, and Chromatographic system—
Proceed as directed in the Assay under Cephradine.
Assay preparation—
Transfer, as completely as possible, the contents of not fewer than 20 Capsules to a suitable tared container, determine the average weight per Capsule, and mix the combined contents. Transfer an accurately weighed portion of the powder, equivalent to about 125 mg of cephradine, to a 250-mL volumetric flask, add 50 mL of Mobile phase, sonicate for about 15 minutes, and shake by mechanical means for about 10 minutes. Dilute with Mobile phase to volume, and mix. Filter a portion of this mixture through a filter having a porosity of 0.5 µm or finer, discarding the first 5 mL of the filtrate. Use the filtrate as the Assay preparation.
Procedure—
Separately inject equal volumes (about 10 µL) of the
Standard cephradine preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of cephradine (sum of cephradine and cephalexin) in the portion of Capsules taken by the formula:
0.25CP(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Cephradine RS in the
Standard preparation;
P is the designated potency, in µg per mg, of
USP Cephradine RS; and
rU and
rS are the sums of the cephradine and cephalexin peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
