Chloramphenicol and Polymyxin B Sulfate Ophthalmic Ointment
»Chloramphenicol and Polymyxin B Sulfate Ophthalmic Ointment contains not less than 90.0percent and not more than 120.0percent of the labeled amount of chloramphenicol (C11H12Cl2N2O5)and not less than 90.0percent and not more than 125.0percent of the labeled amount of polymyxin B.
Packaging and storage— Preserve in collapsible ophthalmic ointment tubes.
Identification— The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparationas obtained in the Assay for chloramphenicol.
Sterility á71ñ: meets the requirements.
Metal particles— It meets the requirements of the test for Metal Particles in Ophthalmic Ointments á751ñ.
Assay for chloramphenicol—
Mobile phase and Chromatographic system—Proceed as directed in the Assayunder Chloramphenicol.
Standard preparation— Proceed as directed for Standard preparationin the Assayunder Chloramphenicol Ophthalmic Ointment.
Assay preparation— Using Ophthalmic Ointment,proceed as directed for Assay preparationin the Assayunder Chloramphenicol Ophthalmic Ointment.
Procedure— Proceed as directed for Procedurein the Assayunder Chloramphenicol.Calculate the quantity,in mg,of C11H12Cl2N2O5in the portion of Ophthalmic Ointment taken by the formula:
0.25C(rU/rS),
in which the terms are as defined therein.
Assay for polymyxin— Proceed as directed for polymyxin under Antibiotics—Microbial Assays á81ñ,using an accurately weighed portion of Ophthalmic Ointment,equivalent to about 5000Polymyxin B Units,shaken in a separator containing about 50mLof ether and extracted with four 20-mLportions of Buffer No.6.Combine the aqueous extracts in a 100-mLvolumetric flask,dilute with Buffer No.6to volume,and mix.Dilute an accurately measured portion of this solution quantitatively with Buffer No.6to obtain a Test Dilutionhaving a concentration assumed to be equal to the median dose level of the Standard.
Auxiliary Information— Staff Liaison:William W.Wright,Ph.D.,Scientific Fellow
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 431
Phone Number:1-301-816-8335