Erythromycin Delayed-Release Capsules

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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Erythromycin Delayed-Release Capsules contain not less than 90.0 percent and not more than 115.0 percent of the labeled amount of erythromycin (C₃₇H₆₇NO₁₃).

Packaging and storage-Preserve in tight containers.

USP REFERENCE STANDARDS (11)-

USP Erythromycin RS

1 Identification

Prepare a test solution by mixing a quantity of finely ground Capsule contents with methanol to obtain a concentration of about 2.5 mg of erythromycin per mL. Prepare a Standard solution of USP Erythromycin RS in methanol containing 2.5 mg per mL. Apply separately 10 µL of each solution to a thin-layer chromatographic plate (see Chromatography (621)) 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 7 cm. 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 100 for 10 minutes, and examine the chromatogram, in which erythromycin appears as a black-to-purple spot: the R, value of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.

DISSOLUTION (711)-Proceed as directed for Procedure for Method B under Apparatus 1 and Apparatus 2, Delayed-Release Dosage Forms.

Apparatus 1: 50 rpm.

Times: 60 minutes for Acid Stage; 60 minutes for Buffer Stage.

Procedure-Transfer the contents of 1 Capsule to the apparatus. Proceed as directed for Acid Stage, 900 mL of 0.06 N hydrochloric acid being placed in the vessel instead of 1000 mL of 0.1 N hydrochloric acid, and the apparatus operated for 60 minutes instead of 2 hours. Do not perform an analysis at the end of the Acid stage. Continue as directed for Buffer Stage, 900 mL of the pH 6.8 phosphate buffer being used instead of 1000 mL. Determine the amount of C₃₇H₆₇NO₁₃ dissolved after 120 minutes by assaying a filtered portion of the solution under test as directed under Antibiotics-Microbial Assays (81),

Tolerances-Not less than 80% (Q) of the labeled amount of C₃₇H₆₇NO₁₃ is dissolved in 120 minutes. 13

WATER DETERMINATION, Method I (921): not more than 7.5%, 20 mL of methanol containing 10% of imidazole being used in place of methanol in the titration vessel.

2 Assay

Proceed as directed under Antibiotics-Microbial Assays (81), using not less than 5 Capsules blended for about 3 minutes in a high-speed glass blender jar containing 200 mL of methanol. Add 300 mL of Buffer B.3, and blend again for about 3 minutes. Dilute an accurately measured volume of this stock solution quantitatively with Buffer B.3 to obtain a Test Dilution having a concentration assumed to be equal to the median dose level of the Standard.