Erythromycin Topical Solution
» Erythromycin Topical Solution is a solution of Erythromycin in a suitable vehicle. It contains not less than 90.0 percent and not more than 125.0 percent of the labeled amount of C37H67NO13.
Packaging and storage Preserve in tight containers.
USP Reference standards 11
Identification Prepare a test solution by mixing a portion of the Topical Solution with methanol to obtain a concentration of about 2.5 mg of erythromycin per mL. Proceed as directed in the Identification test under Erythromycin Delayed-Release Capsules, beginning with Prepare a Standard solution of USP Erythromycin RS.
Water, Method I 921: not more than 8.0% if it contains 20 mg per mL, or not more than 5.0% if it contains 15 mg per mL, or not more than 2.0% if it contains acetone, 20 mL of a mixture of pyridine and methanol (1:1) being used in place of methanol in the titration vessel.
Alcohol content, Method II 611: between 92.5% and 107.5% of the labeled amount of C2H5OH.
Assay Proceed as directed under AntibioticsMicrobial Assays 81, using an accurately measured volume of Topical Solution diluted quantitatively with Buffer No. 3 to yield a Test Dilution having a concentration assumed to be equal to the median dose level of the Standard.
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USP35NF30 Page 3082