Packaging and storage— Preserve in tight containers.

USP Reference standards 11— USP Erythromycin RS.

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.

Residual solvents 467: meets the requirements.

Assay— Proceed as directed under Antibiotics—Microbial 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.

Expert Committee : (MDANT05) Monograph Development-Antibiotics

USP29–NF24 Page 832

Phone Number : 1-301-816-8223