Packaging and storage— Preserve in tight containers.

Labeling— Label Pledgets to indicate that each Pledget is to be used once and then discarded.Label Pledgets also to indicate the volume,in mL,of Erythromycin Topical Solution contained in each Pledget,and the concentration,in mg of erythromycin per mL,of the Erythromycin Topical Solution.

USP Reference standards á11ñ— USP Erythromycin RS.

Other requirements— The Erythromycin Topical Solution expressed from Pledgets meets the requirements for Identification,Water,and Alcohol contentunder Erythromycin Topical Solution.

Topical solution assay— Proceed as directed for erythromycin under Antibiotics—Microbial Assays á81ñ,using the solution expressed from not less than 10Pledgets.Dilute an accurately measured volume of this solution quantitatively with Buffer No.3to obtain a Test Dilutionhaving a concentration assumed to be equal to the median dose level of the Standard.

Assay and minimum volume— Proceed as directed for erythromycin under Antibiotics—Microbial Assays á81ñ,assaying 10Pledgets individually.Transfer 1Pledget to a suitable container,add about 50mLof Buffer No.3,and shake for 2minutes.Transfer the solution so obtained to a 100-mLvolumetric flask.Wash the Pledget with two 20-mLportions of Buffer No.3,add the washings to the 100-mLvolumetric flask,dilute with Buffer No.3to volume,and mix.Dilute an accurately measured volume of this solution quantitatively with Buffer No.3to obtain a Test Dilutionhaving a concentration assumed to be equal to the median dose level of the Standard.Calculate the volume,in mL,of Erythromycin Topical Solution in each Pledget taken by dividing the number of mg of erythromycin in each individual Pledget by the number of mg of erythromycin in each mLof Erythromycin Topical Solution as obtained in the Topical Solution assay.The volume of Erythromycin Topical Solution in each Pledget is not less than 90.0%of the labeled amount.If this requirement is not met,determine the volume of Erythromycin Topical Solution in each of 20additional Pledgets.The volume of Erythromycin Topical Solution in not more than 1of the 30Pledgets is less than 90.0%of the labeled amount.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 761

Phone Number:1-301-816-8335