(Ph. Eur. 11.6 update)
Action and use
Macrolide antibacterial.
DEFINITION
Erythromycin Lactobionate for Infusion is a sterile material consisting of Erythromycin Lactobionate with or without excipients. It is supplied in a sealed container.
The contents of the sealed container comply with the requirements for Powders for Injections or Infusions stated under Parenteral Preparations and with the following requirements.
Content of erythromycins, calculated as the sum of erythromycin A (C37H67NO13), erythromycin B (C37H67NO12) and erythromycin C (C36H65NO13)
95.0 to 110.0% of the stated amount of erythromycin.
IDENTIFICATION
The infrared absorption spectrum, Appendix II A, of the dry powder, is concordant with the reference spectrum of erythromycin lactobionate (RS 126).
TESTS
Acidity or alkalinity
pH of a solution containing the equivalent of 1.34% w/v of erythromycin, 6.5 to 7.5, Appendix V L.
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions in solution A. Prepare the solutions immediately before use and protect from light.
Solution A 40 volumes of a 1.15% w/v solution of dipotassium hydrogen orthophosphate adjusted to pH 8.0 using dilute phosphoric acid and 60 volumes of methanol R1.
(1) Dissolve a quantity of the contents of a sealed container to produce a solution containing the equivalent of 0.4% w/v erythromycin.
(2) Dilute 1 volume of solution (1) to 100 volumes.
(3) 0.4% w/v of erythromycin for system suitability EPCRS.
(4) Dilute 1 volume of solution (2) to 5 volumes.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with end-capped polar-embedded octadecylsilyl amorphous organosilica polymer (3.5 μm) (X-Terra RP18 is suitable).
(b) Use gradient elution and the mobile phase described below.
(c) Use a flow rate of 1.0 mL per minute.
(d) Use a column temperature of 65°.
(e) Use a detection wavelength of 210 nm.
(f) Inject 100 μL of each solution.
MOBILE PHASE
Mobile phase A 5 volumes of a 3.5% w/v solution of dipotassium hydrogen orthophosphate previously adjusted to pH 7.0 using dilute phosphoric acid, 35 volumes of acetonitrile R1 and 60 volumes of water.
Mobile phase B 5 volumes of a 3.5% w/v solution of dipotassium hydrogen orthophosphate previously adjusted to pH 7.0 using dilute phosphoric acid, 50 volumes of acetonitrile R1 and 45 volumes of water.
| Time (Minutes) | Mobile phase A (% v/v) | Mobile phase B (% v/v) | Comment |
| 0-44 | 100 | 0 | isocratic |
| 44-46 | 100→0 | 0→100 | linear gradient |
| 46-61 | 0 | 100 | isocratic |
| 61-63 | 0→100 | 100→0 | linear gradient |
| 63-80 | 100 | 0 | re-equilibration |
When the chromatograms are recorded under the prescribed conditions, the relative retentions with reference to erythromycin A (retention time about 23 minutes) are: impurity A, about 0.4; impurity B, about 0.5; erythromycin C, about 0.55; impurity L, about 0.63; impurity C, about 0.9; impurity D, about 1.6; erythromycin B, about 1.75; impurity F, about 1.8 and impurity E, about 2.3.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3):
the resolution between the peaks due to impurity B and erythromycin C is at least 1.2;
the peak-to-valley ratio is at least 2.0, where Hp is the height above the baseline of the peak due to impurity C and Hv is the height above the baseline of the lowest point of the curve separating this peak from the peak due to erythromycin A;
the peak-to-valley ratio is at least 1.5, where Hp is the height above the baseline of the peak due to impurity F and Hv is the height above the baseline of the lowest point of the curve separating this peak from the peak due to erythromycin B.
LIMITS
Identify any peaks corresponding to impurities D, E, F and L in the chromatogram obtained with solution (1), using the chromatogram obtained with solution (3), and multiply the areas of these peaks by the corresponding correction factors: impurity D, 2.0; impurity E, 0.08; impurity F, 0.08; impurity L, 0.11.
In the chromatogram obtained with solution (1):
the area of any peak corresponding to impurity C is not greater than 3 times the area of the principal peak in the chromatogram obtained with solution (2) (3%);
the area of any peak corresponding to impurity A or B is not greater than twice the area of the principal peak in the chromatogram obtained with solution (2) (2% of each);
the area of any peak corresponding to impurity D, E or F is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1% of each);
the area of any peak corresponding to impurity L is not greater than 0.4 times the area of the principal peak in the chromatogram obtained with solution (2) (0.4%);
the area of any other secondary peak, other than the peaks due to erythromycin B and C is not greater than 0.4 times the area of the principal peak in the chromatogram obtained with solution (2) (0.4%);
the sum of the areas of any secondary peaks, other than the peaks due to erythromycin B and C is not greater than 7 times the area of the principal peak in the chromatogram obtained with solution (2) (7%).
Disregard any peak due to erythromycin B and erythromycin C and any peak with an area less than the area of the principal peak in the chromatogram obtained with solution (4) (0.2%).
The content of each of erythromycin B and erythromycin C, as determined under Assay, is not more than 5%.
ASSAY
Determine the weight of the contents of 10 sealed containers as described in the test for uniformity of weight, Appendix XII C1, Powders for Parenteral Administration.
Carry out the method for liquid chromatography, Appendix III D, using the following solutions in solution A. Prepare the solutions immediately before use and protect from light.
Solution A 40 volumes of a 1.15% w/v solution of dipotassium hydrogen orthophosphate adjusted to pH 8.0 using dilute phosphoric acid and 60 volumes of methanol R1.
(1) Dilute a quantity of the mixed contents of sealed containers to produce a solution containing the equivalent of 0.4% w/v of Erythromycin.
(2) 0.4% w/v of erythromycin BPCRS.
(3) 0.4% w/v of erythromycin for system suitability EPCRS.
CHROMATOGRAPHIC CONDITIONS
The chromatographic conditions described under Related substances may be used.
SYSTEM SUITABILITY
The test is not valid unless, in the chromatogram obtained with solution (3):
the resolution between the peaks due to impurity B and erythromycin C is at least 1.2;
the peak-to-valley ratio is at least 2.0, where Hp is the height above the baseline of the peak due to impurity C and Hv is the height above the baseline of the lowest point of the curve separating this peak from the peak due to erythromycin A;
the peak-to-valley ratio is at least 1.5, where Hp is the height above the baseline of the peak due to impurity F and Hv is the height above the baseline of the lowest point of the curve separating this peak from the peak due to erythromycin B.
DETERMINATION OF CONTENT
Calculate the percentage content of erythromycin A (C37H67NO13), erythromycin B (C37H67NO12) and erythromycin C (C36H65NO13) using the chromatograms obtained with solutions (1) and (2) and the declared contents of C37H67NO13, C37H67NO12 and C36H65NO13 respectively in erythromycin BPCRS.
LABELLING
The label of the sealed container states the quantity of active ingredient contained in it in terms of the equivalent amount of erythromycin.
IMPURITIES
The impurities limited by the requirements of this monograph include those listed under Erythromycin Lactobionate.
