Erythromycin Stearate Tablets

General Notices

Action and use

Macrolide antibacterial.

Definition

Erythromycin Stearate Tablets contain Erythromycin Stearate.

The tablets comply with the requirements stated under Tablets and with the following requirements.

Identification

A. To a quantity of the powdered tablets containing the equivalent of 0.1 g of erythromycin add 10 mL of water and shake well. Decant the supernatant liquid and discard. Extract the residue by shaking with 10 mL of methanol, filter the extract and evaporate to dryness. The infrared absorption spectrum, Appendix II A, of the residue after drying at a pressure not exceeding 0.7 kPa is concordant with the reference spectrum of erythromycin stearate (RS 127).
B. Dissolve a quantity of the powdered tablets containing the equivalent of 3 mg of erythromycin in 2 mL of acetone and add 2 mL of hydrochloric acid; an orange colour is produced which changes to red and then to deep violet–red. Add 2 mL of chloroform and shake; the chloroform layer becomes violet.
C. Extract a quantity of the powdered tablets containing the equivalent of 50 mg of erythromycin with 10 mL of chloroform, filter and evaporate to dryness. Heat 0.1 g of the residue gently with 5 mL of 2m hydrochloric acid and 10 mL of water until the solution boils; oily globules rise to the surface. Cool, remove the fatty layer, heat it with 3 mL of 0.1m sodium hydroxide and allow to cool; the solution sets to a gel. Add 10 mL of hot water and shake; the solution froths. To 1 mL add a 10% w/v solution of calcium chloride; a granular precipitate is produced which is insoluble in hydrochloric acid.

Tests

Dissolution

Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules, Appendix XII B1, using Apparatus 2. Use as the medium 900 mL of a 2.722% w/v solution of sodium acetate, the pH of which has been adjusted to 5.0 with glacial acetic acid and rotate the paddle at 50 revolutions per minute. Transfer 5 mL of a filtered sample to a graduated flask, add 40 mL of glacial acetic acid and 10 mL of a 0.5% w/v solution of 4-dimethylaminobenzaldehyde in glacial acetic acid and dilute to 100 mL with a mixture of 35 volumes of glacial acetic acid and 70 volumes of hydrochloric acid. Allow to stand for 15 minutes and measure the absorbance of the resulting solution at the maximum at 485 nm, Appendix II B, using in the reference cell dissolution medium that has been subjected to the conditions of the test. Prepare a suitable solution of erythromycin stearate BPCRS in the dissolution medium and filter. Transfer 5 mL of the filtered solution to a graduated flask, add 40 mL of glacial acetic acid and 10 mL of a 0.5% w/v solution of 4-dimethylaminobenzaldehyde in glacial acetic acid and dilute to 100 mL with a mixture of 35 volumes of glacial acetic acid and 70 volumes of hydrochloric acid. Allow to stand for 15 minutes and measure the absorbance of the resulting solution at the maximum at 485 nm, Appendix II B, using in the reference cell dissolution medium that has been subjected to the conditions of the test. Calculate the total content of C37H67NO13 in the medium from the absorbances obtained using the declared content of C37H67NO13 in erythromycin stearate BPCRS.

Assay

Weigh and powder 20 tablets. Dissolve a quantity of the powder containing the equivalent of 25 mg of erythromycin as completely as possible in sufficient methanol to produce 100 mL 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 the tablets, taking each 1000 IU found to be equivalent to 1 mg of erythromycin. The upper fiducial limit of error is not less than 97.0% and the lower fiducial limit of error is not more than 110.0% of the stated content.

Storage

Erythromycin Stearate Tablets should be protected from light.

Labelling

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