Clindamycin Phosphate Vaginal Cream
» Clindamycin Phosphate Vaginal Cream contains an amount of Clindamycin Phosphate equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of clindamycin (C18H33ClN2O5S).
Packaging and storage Preserve in well-closed containers.
USP Reference standards 11
Identification The chromatogram of the Assay preparation obtained as directed in the Assay exhibits a major peak for clindamycin phosphate, the retention time of which corresponds to that in the chromatogram of the Standard preparation as obtained in the Assay.
pH 791: between 3.0 and 6.0, determined on the undiluted Cream.
Mobile phase , Resolution solution, Standard preparation, and Chromatographic systemProceed as directed in the Assay under Clindamycin Phosphate Gel.
Assay preparation Transfer an accurately weighed quantity of Cream, equivalent to about 20 mg of clindamycin (C18H33ClN2O5S), to a 125-mL conical flask, add 100.0 mL of Mobile phase and about 10 glass beads (about 10 mm in diameter). Insert the stopper in the flask securely, and shake by mechanical means at 50 for about 1 hour. Cool in an ice bath for about 20 minutes, and centrifuge. Filter a few mL of the cloudy lower layer through a filter of 2 µm or finer porosity, and use the filtrate as the Assay preparation.
Procedure Proceed as directed for Procedure in the Assay under Clindamycin Phosphate Gel. Calculate the quantity, in mg, of clindamycin (C18H33ClN2O5S) in the portion of Cream taken by the formula:
0.1CE(rU / rS)in which the terms are as defined therein.
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USP35NF30 Page 2706