(Ph. Eur. monograph 1098)
Action and use
Macrolide antibacterial.
Preparation
Erythromycin Lactobionate for Infusion
DEFINITION
Mixture of the lactobionate salts of erythromycin.
Main component (3R,4S,5S,6R,7R,9R,11R,12R,13S,14R)-4-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-
hexopyranosyl)oxy]-14-ethyl-7,12,13-trihydroxy-3,5,7,9,11,13-hexamethyl-6-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]oxacyclotetradecane-2,10-dione 4-O-β-D-galactopyranosyl-D-gluconate (erythromycin A lactobionate).
Salt of a product obtained by fermentation using a strain of Streptomyces erythreus.
Content
— sum of erythromycins A, B and C expressed as lactobionates: 93.0 per cent to 102.0 per cent (anhydrous substance);
— erythromycin B lactobionate: maximum 5.0 per cent (anhydrous substance);
— erythromycin C lactobionate: maximum 5.0 per cent (anhydrous substance).
CHARACTERS
Appearance
White or slightly yellow, hygroscopic powder.
Solubility
Soluble in water, freely soluble in anhydrous ethanol and in methanol, very slightly soluble in acetone and in methylene chloride.
IDENTIFICATION
Infrared absorption spectrophotometry (2.2.24).
Comparison erythromycin lactobionate CRS.
TESTS
Appearance of solution
The solution is clear (2.2.1) and colourless (2.2.2, Method II).
Dissolve 1.0 g in 20 mL of water R.
pH (2.2.3)
6.5 to 7.5.
Dissolve 0.50 g in carbon dioxide-free water R and dilute to 25 mL with the same solvent.
Related substances
Liquid chromatography (2.2.29). Prepare the solutions immediately before use.
Solution A: Dissolve 11.5 g of dipotassium hydrogen phosphate R in 900 mL of water R, adjust to pH 8.0 with dilute phosphoric acid R and dilute to 1000 mL with water R.
Solvent mixture methanol R, solution A (40:60 V/V).
Test solution: Dissolve 60.0 mg of the substance to be examined in the solvent mixture and dilute to 10.0 mL with the solvent mixture.
Reference solution (a): Dissolve 40.0 mg of erythromycin A CRS in the solvent mixture and dilute to 10.0 mL with the solvent mixture.
Reference solution (b): Dissolve 10.0 mg of erythromycin B CRS and 10.0 mg of erythromycin C CRS in the solvent mixture and dilute to 50.0 mL with the solvent mixture.
Reference solution (c): Dilute 1.0 mL of reference solution (a) to 100.0 mL with the solvent mixture.
Reference solution (d): Dissolve 4 mg of erythromycin for system suitability CRS (containing impurities A, B, C, D, E, F, H and L) in the solvent mixture and dilute to 1 mL with the solvent mixture.
Column:
— size: l = 0.25 m, Ø = 4.6 mm;
— stationary phase: end-capped polar-embedded octadecylsilyl amorphous organosilica polymer R (3.5 μm);
— temperature: 65 °C; preheating the mobile phase may be required, for instance by extending the inlet tubing in the oven to 30 cm.
Mobile phase:
— mobile phase A: phosphate buffer solution pH 7.0 R7, acetonitrile R1, water for chromatography R (5:35:60 V/V/V);
— mobile phase B: phosphate buffer solution pH 7.0 R7, water for chromatography R, acetonitrile R1 (5:45:50 V/V/V);
| Time (min) |
Mobile phase A (per cent V/V) |
Mobile phase B (per cent V/V) |
| 0 – tR | 100 | 0 |
| tR– (tR+ 2) | 100 → 0 | 0 → 100 |
| tR+ 2) – (tR+ 15) | 0 | 100 |
tR = retention time of erythromycin B, determined by injecting 10 μL of reference solution (b) and eluting with mobile phase A
Flow rate 1.0 mL/min.
Detection: Spectrophotometer at 210 nm.
Autosampler Set at 4 °C.
Injection 100 μL of the test solution and reference solutions (b), (c) and (d).
Identification of impurities: Use the chromatogram supplied with erythromycin for system suitability CRS and the chromatogram obtained with reference solution (d) to identify the peaks due to impurities A, B, C, D, E, F, H and L; use the chromatogram obtained with reference solution (b) to identify the peaks due to erythromycins B and C.
Relative retention: With reference to erythromycin A (retention time = about 23 min): impurity H = about 0.3;
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 1.61; erythromycin B = about 1.75; impurity F = about 1.81; impurity E = about 2.3.
System suitability Reference solution (d):
— resolution: minimum 1.2 between the peaks due to impurity B and erythromycin C;
— peak-to-valley ratio: minimum 1.5, where Hp = height above the baseline of the peak due to impurity F and Hv = height above the baseline of the lowest point of the curve separating this peak from the peak due to erythromycin B; minimum 2.0, where Hp = height above the baseline of the peak due to impurity C and Hv = height above the baseline of the lowest point of the curve separating this peak from the peak due to erythromycin A. If necessary, adjust the concentration of acetonitrile R1 in the mobile phases and/or the gradient to obtain the required separation.
Calculation of percentage contents:
— correction factors: multiply the peak areas of the following impurities by the corresponding correction factor: impurity D = 2; impurity E = 0.08; impurity F = 0.08; impurity L = 0.11;
— for each impurity, use the concentration of erythromycin A in reference solution (c).
Limits:
— impurity C: maximum 3.0 per cent;
— impurities A, B: for each impurity, maximum 2.0 per cent;
— impurities D, E, F, H: for each impurity, maximum 1.0 per cent;
— impurity L: maximum 0.4 per cent;
— any other impurity: for each impurity, maximum 0.4 per cent;
— total: maximum 7.0 per cent;
— reporting threshold: 0.2 per cent; disregard the peaks due to erythromycins B and C.
Free lactobionic acid
Maximum 1.0 per cent of C12H22O12 (anhydrous substance).
Dissolve 0.400 g in 50 mL of water R. Titrate with 0.1 M sodium hydroxide, determining the end-point potentiometrically (2.2.20). Calculate the volume of 0.1 M sodium hydroxide required per gram of the substance to be examined (n1 mL).
Dissolve 0.500 g in 40 mL of anhydrous acetic acid R and titrate with 0.1 M perchloric acid, determining the end-point potentiometrically (2.2.20). Calculate the volume of 0.1 M perchloric acid required per gram of the substance to be examined (n2 mL).
Calculate the percentage content of C12H22O12 using the following expression:
Water (2.5.12)
Maximum 5.0 per cent, determined on 0.200 g.
Use a 100 g/L solution of imidazole R in anhydrous methanol R as the solvent.
Sulfated ash (2.4.14)
Maximum 0.5 per cent, determined on 1.0 g.
ASSAY
Liquid chromatography (2.2.29) as described in the test for related substances with the following modifications.
Injection Test solution and reference solutions (a) and (b).
System suitability Reference solution (a):
— symmetry factor: maximum 2.5 for the peak due to erythromycin A;
— repeatability: maximum relative standard deviation of 1.0 per cent determined on 6 injections.
Calculate the percentage content of erythromycin A (C37H67NO13)using the chromatogram obtained with reference solution (a). Calculate the percentage contents of erythromycin B (C37H67NO12) and erythromycin C (C37H67NO13) using the chromatogram obtained with reference solution (b).
Express the result as erythromycin A lactobionate, erythromycin B lactobionate and erythromycin C lactobionate by multiplying the percentage content of erythromycin A by 1.4877, the percentage content of erythromycin B by 1.4986 and the percentage content of erythromycin C by 1.4972.
For the calculation of content of erythromycin lactobionate, use the sum of erythromycins A, B and C expressed as lactobionates as described above.
STORAGE
In an airtight container, protected from light. If the substance is sterile, the container is also sterile and tamper-evident.
IMPURITIES
Specified impurities A, B, C, D, E, F, H, L.
Other detectable impurities (the following substances would, if present at a sufficient level, be detected by one or other of the tests in the monograph. They are limited by the general acceptance criterion for other/unspecified impurities. It is therefore not necessary to identify these impurities for demonstration of compliance. See also 5.10. Control of impurities in substances for pharmaceutical use) I, J, K, M, N.
A. (3R,4S,5S,6R,7R,9R,11R,12R,13S,14R)-4-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-14-ethyl- 7,12,13-trihydroxy-3-(hydroxymethyl)-5,7,9,11,13-pentamethyl-6-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo- hexopyranosyl]oxy]oxacyclotetradecane-2,10-dione (erythromycin F),
B. (3R,4S,5S,6R,7R,9R,11R,12R,13S,14R)-4-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-14-ethyl- 7,12,13-trihydroxy-3,5,7,9,11,13-hexamethyl-6-[[3,4,6-trideoxy-3-(methylamino)-β-D-xylo- hexopyranosyl]oxy]oxacyclotetradecane-2,10-dione (3′′-N-demethylerythromycin A),
C. (2S,4aR,4′R,5′S,6′S,7R,8S,9R,10R,12R,14R,15R,16S,16aS)-7-ethyl-5′,8,9,14-tetrahydroxy-4′-methoxy-
4′,6′,8,10,12,14,16-heptamethyl-15-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo- hexopyranosyl]oxy]hexadecahydrospiro[5H,11H-1,3-dioxino[5,4-c]oxacyclotetradecin-2,2′-pyrane]-5,11-dione (erythromycin E),
D. (1S,2R,3R,4S,5R,8R,9S,10S,11R,12R,14R)-9-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-5-ethyl-3-hydroxy-2,4,8,10,12,14-hexamethyl-11-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]-6,15,16-trioxatricyclo[10.2.1.1 ]hexadecan-7-one (anhydroerythromycin A),
E. (2R,3R,4S,5R,8R,9S,10S,11R,12R)-9-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-5-ethyl-3,4- dihydroxy-2,4,8,10,12,14-hexamethyl-11-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]-6,15-dioxabicyclo[10.2.1]pentadec-1(14)-en-7-one (erythromycin A enol ether),
F. (2R,3R,6R,7S,8S,9R,10R)-7-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-3-[(1R,2R)-1,2-dihydroxy-1-methylbutyl]-2,6,8,10,12-pentamethyl-9-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]-4,13-dioxabicyclo[8.2.1]tridec-1(12)-en-5-one (pseudoerythromycin A enol ether),
H. (3R,4S,5S,6R,7R,9R,11R,12R,13S,14R)-4-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-14-ethyl-7,12,13-trihydroxy-3,5,7,9,11,13-hexamethyl-6-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]oxacyclotetradecane-2,10-dione N-oxide (erythromycin A 3′′-N-oxide),
I. (1S,4S,5R,8R,9S,10S,11R,12R,14R)-5-ethyl-9-hydroxy-2,4,8,10,12,14-hexamethyl-11-[[3,4,6-trideoxy-3-
(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]-6,15,16-trioxatricyclo[10.2.1.1 ]hexadec-2-en-7-one (erythralosamine),
J. (1RS,2R,3R,6R,7S,8S,9R,10R,12R)-7-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-3-[(1R,2R)-1,2-dihydroxy-1-methylbutyl]-1-hydroxy-2,6,8,10,12-pentamethyl-9-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]-4,13-dioxabicyclo[8.2.1]tridecan-5-one (pseudoerythromycin A hemiketal),
K. (3R,4S,5S,6R,7R,9R,11R,12S,13R,14R)-4-[(2,6-dideoxy-3-C-methyl-α-L-ribo-hexopyranosyl)oxy]-14-ethyl-7,12-dihydroxy-3,5,7,9,11,13-hexamethyl-6-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]oxacyclotetradecane-2,10-dione (erythromycin D),
L. (3R,4S,5S,6R,7R,9R,11R,12R,13S,14R)-4-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-14-ethyl-7,12,13-trihydroxy-3,5,7,9,11,13-hexamethyl-6-[[3,4,6-trideoxy-3-(formylmethylamino)-β-D-xylo- hexopyranosyl]oxy]oxacyclotetradecane-2,10-dione (3′′-N-demethyl-3′′-N-formylerythromycin A),
M. (3R,4S,5S,6R,7R,9R,11R,12S,13R,14R)-4-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl)oxy]-14-ethyl-7,12-dihydroxy-3-(hydroxymethyl)-5,7,9,11,13-pentamethyl-6-[[3,4,6-trideoxy-3-(dimethylamino)-β-D-xylo-hexopyranosyl]oxy]oxacyclotetradecane-2,10-dione (erythromycin G),
N. (3R,4S,5S,6R,7R,9R,11R,12S,13R,14R)-14-ethyl-4,6,7,12-tetrahydroxy-3,5,7,9,11,13-
hexamethyloxacyclotetradecane-2,10-dione (erythronolide B).
