Erythromycin Estolate Capsules

General Notices

Action and use

Macrolide antibacterial.

Definition

Erythromycin Estolate Capsules contain Erythromycin Estolate.

The capsules comply with the requirements stated under Capsules and with the following requirements.

Identification

A. The infrared absorption spectrum of the contents of the capsules, Appendix II A, is concordant with the reference spectrum of erythromycin estolate (RS 124).
B. In the test for Related substances, the principal spot in the chromatogram obtained with solution (2) is similar in position and colour to that in the chromatogram obtained with solution (3).

Tests

Disintegration

Maximum time, 30 minutes, Appendix XII A1. Use a 0.6% v/v solution of hydrochloric acid in place of water.

Water

The contents of the capsules contain not more than 5.0% w/w of water, Appendix IX C. Use 0.5 g.

Related substances

Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.

(1) Shake a quantity of the contents of the capsules containing the equivalent of 0.4 g of erythromycin with 100 mL of acetone, filter and use the filtrate.
(2) Dilute 1 volume of solution (1) to 4 volumes with acetone.
(3) 0.13% w/v of erythromycin estolate BPCRS in acetone.
(4) 0.1% w/v each of erythromycin estolate BPCRS and erythromycin ethylsuccinate BPCRS in acetone.
(5) 0.01% w/v of erythromycin A BPCRS in acetone.
chromatographic conditions
(a) Use a silica gel precoated plate (Merck silica gel 60 plates are suitable).
(b) Use the mobile phase described below.
(c) Apply 10 µL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate allow it to dry in air, spray with anisaldehyde solution, heat at 110° for 5 minutes and allow to cool.
mobile phase

1 volume of a 15% w/v solution of ammonium acetate, previously adjusted to pH 7.0, 15 volumes of ethanol (96%) and 85 volumes of chloroform.

system suitability

The test is not valid unless the chromatogram obtained with solution (4) shows two clearly separated spots.

limits

Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (5) (2.5%, with respect to erythromycin).

Assay

Dissolve a quantity of the mixed contents of 20 capsules containing the equivalent of 0.25 g of erythromycin in 400 mL of methanol and add 200 mL of sterile phosphate buffer pH 7.0 and sufficient water for injections to produce 1000 mL. Maintain the solution at 60° for 3 hours, cool, filter and carry out the microbiological assay of antibiotics for erythromycin, Appendix XIV A. The precision of the assay is such that the fiducial limits of error are not less than 95% and not more than 105% of the estimated potency.

Calculate the content of erythromycin in a capsule of average content weight, taking each 1000 IU found to be equivalent to 1 mg of erythromycin. The upper fiducial limit of error is not less than 95.0% and the lower fiducial limit of error is not more than 110.0% of the stated content.

Labelling

The quantity of active ingredient is stated in terms of the equivalent amount of erythromycin.