Packaging and storage— Preserve in tight containers.

USP Reference standards á11ñ— USP Erythromycin RS.

Identification— Prepare a test solution by mixing a quantity of finely ground Capsule contents with methanol to obtain a concentration of about 2.5mg of erythromycin per mL.Prepare a Standard solution of USP Erythromycin RSin methanol containing 2.5mg per mL.Apply separately 10µLof each solution to a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Place the plate in an unlined chromatographic chamber,and develop the chromatogram in a solvent system consisting of a mixture of methanol and chloroform (85:15)until the solvent front has moved about 7cm.Remove the plate from the chamber,mark the solvent front,and allow the solvent to evaporate.Spray the plate with a mixture of alcohol,p-methoxybenzaldehyde,and sulfuric acid (90:5:5).Heat the plate at 100for 10minutes,and examine the chromatogram,in which erythromycin appears as a black-to-purple spot:the RFvalue of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.

Drug release,Method Bá724ñ—

Water,Method Iá921ñ: not more than 7.5%,20mLof methanol containing 10%of imidazole being used in place of methanol in the titration vessel.

Assay— Proceed as directed under Antibiotics—Microbial Assays á81ñ,using not less than 5Capsules blended for about 3minutes in a high-speed glass blender jar containing 200mLof methanol.Add 300mLof Buffer No.3,and blend again for about 3minutes.Dilute an accurately measured volume of this stock solution quantitatively with Buffer No.3to obtain a Test Dilutionhaving a concentration assumed to be equal to the median dose level of the Standard.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 758

Phone Number:1-301-816-8335