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.
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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USP32NF27 Page 2286