(Ph. Eur. monograph 0295)
C12H14N4O2S 278.3 57-68-1
Action and use
Sulfonamide antibacterial.
Preparation
Sulfadimidine Injection
DEFINITION
4-Amino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide.
Content
99.0 per cent to 101.0 per cent (dried substance).
CHARACTERS
Appearance
White or almost white powder or crystals.
Solubility
Very slightly soluble in water, soluble in acetone, slightly soluble in ethanol (96 per cent). It dissolves in solutions of alkali hydroxides and in dilute mineral acids.
IDENTIFICATION
First identification: A.
Second identification: B, C, D.
A. Infrared absorption spectrophotometry (2.2.24).
Comparison: sulfadimidine CRS.
B. Thin-layer chromatography (2.2.27).
Solvent mixture: concentrated ammonia R, methanol R (4:96 V/V).
Test solution: Dissolve 20 mg of the substance to be examined in 3 mL of the solvent mixture and dilute to 5.0 mL with the solvent mixture.
Reference solution: Dissolve 20 mg of sulfadimidine CRS in 3 mL of the solvent mixture and dilute to 5.0 mL with the solvent mixture.
Plate: TLC silica gel GF254 plate R.
Mobile phase: dilute ammonia R1, water R, nitromethane R, dioxan R (3:5:40:50 V/V/V/V).
Application: 5 μL.
Development: Over 2/3 of the plate.
Drying: At 100-105 °C for 30 min.
Detection: Examine in ultraviolet light at 254 nm.
Results: The principal spot in the chromatogram obtained with the test solution is similar in position and size to the principal spot in the chromatogram obtained with the reference solution.
C. Place 3 g in a dry tube. Immerse the lower part of the tube, inclined at 45°, in a silicone-oil bath and heat to about 270 °C. The substance to be examined decomposes and a white or yellowish-white sublimate is formed which, after
recrystallisation from toluene R and drying at 100 °C, melts (2.2.14) at 150 °C to 154 °C.
D. Dissolve about 5 mg in 10 mL of a 103 g/L solution of hydrochloric acid R. Dilute 1 mL of the solution to 10 mL with water R. The solution, without further acidification, gives the reaction of primary aromatic amines (2.3.1).
TESTS
Appearance of solution
The solution is not more intensely coloured than reference solution Y5, BY5 or GY5
(2.2.2, Method II).
Dissolve 0.5 g in a mixture of 5 mL of dilute sodium hydroxide solution R and 5 mL of water R.
Acidity
To 1.25 g of the finely powdered substance to be examined, add 25 mL of carbon dioxide-free water R. Heat at about 70 °C for 5 min. Cool in iced water for about 15 min and filter. To 20 mL of the filtrate add 0.1 mL of bromothymol blue solution R1. Not more than 0.2 mL of 0.1 M sodium hydroxide is required to change the colour of the indicator.
Related substances
Liquid chromatography (2.2.29).
Solvent mixture: 40 g/L solution of sodium hydroxide R, acetonitrile R, water R (2.5:25:75 V/V/V).
Test solution: Dissolve 50.0 mg of the substance to be examined in 41 mL of the solvent mixture and dilute to 50.0 mL with water R.
Reference solution (a): Dissolve 5 mg of sulfacetamide sodium CRS (impurity E) and 5 mg of sulfaguanidine CRS (impurity C) in 41 mL of the solvent mixture and dilute to 100.0 mL with water R.
Reference solution (b): Dilute 1.0 mL of the test solution to 100.0 mL with mobile phase B. Dilute 1.0 mL of this solution to 10.0 mL with mobile phase B.
Reference solution (c): Dissolve 20 mg of sulfadimidine for peak identification CRS (containing impurity G) in 16.4 mL of the solvent mixture and dilute to 20.0 mL with water R.
Column:
— size: l = 0.25 m, Ø = 4.6 mm;
— stationary phase: end-capped octylsilyl silica gel for chromatography R (5 μm);
— temperature: 35 °C.
Mobile phase:
— mobile phase A: mix 10 volumes of acetonitrile R and 90 volumes of a 0.6 per cent V/V solution of acetic acid R previously adjusted to pH 6.5 with a 250 g/L solution of ammonia R;
— mobile phase B: mix equal volumes of acetonitrile R and a 0.6 per cent V/V solution of acetic acid R previously adjusted to pH 6.5 with a 250 g/L solution of ammonia R;
| Time (min) |
Mobile phase A (per cent V/V) |
Mobile phase B (per cent V/V) |
| 0 – 25 | 100 | 0 |
| 25 – 35 | 100 → 0 | 0 → 100 |
| 35 – 45 | 0 | 100 |
Flow rate: 1.3 mL/min.
Detection: Spectrophotometer at 241 nm.
Injection: 20 μL.
Identification of impurities: Use the chromatogram supplied with sulfadimidine for peak identification CRS and the chromatogram obtained with reference solution (c) to identify the peak due to impurity G.
Relative retention: With reference to sulfadimidine (retention time = about 20 min): impurity E = about 0.13; impurity C = about 0.15; impurity D = about 0.2; impurity G = about 1.7.
System suitability: Reference solution (a):
— resolution: minimum 2.0 between the peaks due to impurities E and C.
Limits:
— impurities C, D, G: for each impurity, not more than the area of the principal peak in the chromatogram obtained with reference solution (b) (0.10 per cent);
— unspecified impurities: for each impurity, not more than 0.5 times the area of the principal peak in the chromatogram obtained with reference solution (b) (0.05 per cent);
— total: not more than 5 times the area of the principal peak in the chromatogram obtained with reference solution (b) (0.5 per cent);
— disregard limit: 0.3 times the area of the principal peak in the chromatogram obtained with reference solution (b) (0.03 per cent).
Loss on drying (2.2.32)
Maximum 0.5 per cent, determined on 1.000 g by drying in an oven at 105 °C.
Sulfated ash (2.4.14)
Maximum 0.1 per cent, determined on 1.0 g.
ASSAY
Dissolve 0.250 g in a mixture of 20 mL of dilute hydrochloric acid R and 50 mL of water R. Cool the solution in iced water. Carry out the determination of primary aromatic amino- nitrogen (2.5.8), determining the end-point electrometrically.
1 mL of 0.1 M sodium nitrite is equivalent to 27.83 mg of C12H14N4O2S.
STORAGE
Protected from light.
IMPURITIES
Specified impurities C, D, G.
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 and/or by the general monograph Substances for pharmaceutical use (2034). 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) A, B, E, F.
A. 4-amino-N-(4-methylpyrimidin-2-yl)benzenesulfonamide (sulfamerazine),
B. 4-amino-N-pyrimidin-2-ylbenzenesulfonamide (sulfadiazine),
C. (4-aminophenylsulfonyl)guanidine (sulfaguanidine),
D. 4-aminobenzenesulfonamide (sulfanilamide),
E. N-[(4-aminophenyl)sulfonyl]acetamide (sulfacetamide),
F. 4-aminobenzenesulfonic acid (sulfanilic acid),
G. 4-amino-2-chloro-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide or 4-amino-3-chloro-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide.
