(Ph. Eur. monograph 2106)
C10H16ClNO 201.7 116-38-1
Action and use
Cholinesterase inhibitor.
Preparation
Edrophonium Injection
DEFINITION
N-Ethyl-3-hydroxy-N,N-dimethylanilinium chloride.
Content
99.0 per cent to 101.0 per cent (dried substance).
CHARACTERS
Appearance
White or almost white, crystalline powder.
Solubility
Very soluble in water, freely soluble in ethanol (96 per cent), practically insoluble in methylene chloride.
IDENTIFICATION
A. Infrared absorption spectrophotometry (2.2.24).
Comparison edrophonium chloride CRS.
B. It gives reaction (a) of chlorides (2.3.1).
TESTS
Appearance of solution
The solution is clear (2.2.1) and colourless (2.2.2, Method II).
Dissolve 0.5 g in water R and dilute to 25 mL with the same solvent.
pH (2.2.3)
4.0 to 5.0.
Dissolve 1.0 g in carbon dioxide-free water R and dilute to 10.0 mL with the same solvent.
Related substances
Liquid chromatography (2.2.29).
Test solution Dissolve 50.0 mg in water R and dilute to 50.0 mL with the same solvent.
Reference solution (a) Dissolve 10.0 mg of 3-dimethylaminophenol R in acetonitrile R and dilute to 10.0 mL with the same solvent.
Reference solution (b) Mix 1.0 mL of the test solution and 1.0 mL of reference solution (a) and dilute to 100.0 mL with water R. Dilute 10.0 mL of this solution to 100.0 mL with water R.
Column:
— size: l = 0.25 m, Ø = 4.6 mm,
— stationary phase: styrene-divinylbenzene copolymer R (8-10 μm).
Mobile phase Mix 10 volumes of acetonitrile R and 90 volumes of a 7.7 g/L solution of tetramethylammonium bromide R previously adjusted to pH 3.0 with phosphoric acid R.
Flow rate 1 mL/min.
Detection Spectrophotometer at 281 nm.
Injection 20 μL.
Run time Twice the retention time of edrophonium.
Relative retention With reference to edrophonium (retention time = about 3.8 min): impurity A = about 1.3.
System suitability Reference solution (b):
— resolution: minimum 2.0 between the peaks due to edrophonium and impurity A.
Limits:
— impurity A: not more than the area of the corresponding peak in the chromatogram obtained with reference
solution (b) (0.1 per cent),
— any other impurity: for each impurity, not more than the area of the peak due to edrophonium in the chromatogram obtained with reference solution (b) (0.1 per cent),
— total: not more than 5 times the area of the peak due to edrophonium in the chromatogram obtained with reference solution (b) (0.5 per cent),
— disregard limit: 0.5 times the area of the peak due to edrophonium in the chromatogram obtained with reference solution (b) (0.05 per cent).
Loss on drying (2.2.32)
Maximum 0.5 per cent, determined on 1.000 g by drying in a desiccator at a pressure not exceeding 0.7 kPa for 24 h.
Sulfated ash (2.4.14)
Maximum 0.1 per cent, determined on 1.0 g.
Bacterial endotoxins (2.6.14)
Less than 8.3 IU/mg.
ASSAY
Dissolve 0.150 g in 60 mL of a mixture of equal volumes of acetic anhydride R and anhydrous acetic acid R. Titrate with 0.1 M perchloric acid, determining the end-point potentiometrically (2.2.20).
1 mL of 0.1 M perchloric acid is equivalent to 20.17 mg of C10H16ClNO.
STORAGE
Protected from light.
IMPURITIES
Specified impurities A.
A. 3-(dimethylamino)phenol.
