(Ph. Eur. monograph 1453)
C12H21N5O2S2 331.5 76963-41-2
Action and use
Histamine H2 receptor antagonist; treatment of peptic ulcer.
Preparation
Nizatidine Infusion
DEFINITION
(EZ)-N-[2-[[[2-[(Dimethylamino)methyl]thiazol-4-yl]methyl]sulfanyl]ethyl]-N′-methyl-2-nitroethene-1,1-diamine.
Content
97.0 per cent to 102.0 per cent (dried substance).
CHARACTERS
Appearance
Almost white or slightly brownish, crystalline powder.
Solubility
Sparingly soluble in water, soluble in methanol.
IDENTIFICATION
First identification: C.
Second identification: A, B, D.\
A. Melting point (2.2.14): 131 °C to 134 °C.
B. Ultraviolet and visible absorption spectrophotometry (2.2.25).
Test solution: Dissolve 0.10 g in methanol R and dilute to 100.0 mL with the same solvent. Dilute 2.0 mL of the solution to 100.0 mL with methanol R.
Spectral range: 220-350 nm.
Absorption maxima: At 242 nm and 325 nm.
Absorbance ratio: A325/A242 = 2.2 to 2.5.
C. Infrared absorption spectrophotometry (2.2.24).
Comparison: nizatidine CRS.
D. Thin-layer chromatography (2.2.27).
Test solution: Dissolve 50 mg of the substance to be examined in methanol R and dilute to 10 mL with the same solvent.
Reference solution (a): Dissolve 50 mg of nizatidine CRS in methanol R and dilute to 10 mL with the same solvent.
Reference solution (b): Dissolve 50 mg of nizatidine CRS and 50 mg of ranitidine hydrochloride CRS in methanol R and dilute to 10 mL with the same solvent.
Plate: TLC silica gel plate R.
Mobile phase: water R, concentrated ammonia R1, 2-propanol R, ethyl acetate R (4:8:30:50 V/V/V/V).
Application: 5 μL.
Development: Over 2/3 of the plate.
Drying: In air.
Detection: Expose to iodine vapour until the spots are clearly visible. Examine in daylight.
System suitability: Reference solution (b):
— the chromatogram shows 2 clearly separated spots.
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 reference solution (a).
TESTS
Appearance of solution
The solution is clear (2.2.1) and not more intensely coloured than reference solution Y5 (2.2.2, Method II).
Dissolve 0.2 g in a 10 g/L solution of hydrochloric acid R and dilute to 20 mL with the same solution.
pH (2.2.3)
8.5 to 10.0.
Dissolve 0.2 g in carbon dioxide-free water R and dilute to 20 mL with the same solvent.
Related substances
Liquid chromatography (2.2.29).
Solvent mixture: Mobile phase B, mobile phase A (15:85 V/V).
Test solution (a): Dissolve 50 mg of the substance to be examined in the solvent mixture and dilute to 10.0 mL with the solvent mixture.
Test solution (b): Dissolve 15.0 mg of the substance to be examined in the solvent mixture and dilute to 50.0 mL with the solvent mixture.
Reference solution (a): Dilute 1.0 mL of test solution (a) to 100.0 mL with the solvent mixture. Dilute 1.0 mL of this solution to 10.0 mL with the solvent mixture.
Reference solution (b): Dissolve 15.0 mg of nizatidine CRS in the solvent mixture and dilute to 50.0 mL with the solvent mixture.
Reference solution (c): Dissolve 5 mg of the substance to be examined and 0.5 mg of nizatidine impurity F CRS in the solvent mixture and dilute to 100.0 mL with the solvent mixture.
Reference solution (d): Dissolve 5 mg of 2-(dimethylamino)thioacetamide hydrochloride R (impurity H hydrochloride) in the solvent mixture and dilute to 10.0 mL with the solvent mixture. Dilute 1.0 mL of the solution to 20.0 mL with the solvent mixture. Use 1.0 mL of this solution to dissolve 5 mg of nizatidine for system suitability CRS (containing impurities A, B, C, D, G, J and K).
Column:
— size: l = 0.25 m, Ø = 4.6 mm;
— stationary phase: octadecylsilyl silica gel for chromatography R (5 μm).
Mobile phase:
— mobile phase A: dissolve 5.9 g of ammonium acetate R in 760 mL of water R, add 1 mL of diethylamine R, and adjust to pH 7.5 with acetic acid R;
— mobile phase B: methanol R;
| Time (min) |
Mobile phase A (per cent V/V) |
Mobile phase B (per cent V/V) |
| 0 – 3 | 85 | 15 |
| 3 – 20 | 85 → 50 | 15 → 50 |
| 20 – 45 | 50 | 50 |
Flow rate: 1.0 mL/min.
Detection: Spectrophotometer at 254 nm.
Injection: 20 μL of test solution (a) and reference solutions (a), (c) and (d).
Identification of impurities: Use the chromatogram supplied with nizatidine for system suitability CRS and the chromatogram obtained with reference solution (d) to identify the peaks due to impurities A, B, C, D, G, H, J and K; use the chromatogram obtained with reference solution (c) to identify the peak due to impurity F.
Relative retention: With reference to nizatidine (retention time = about 18 min): impurity A = about 0.19; impurity K = about 0.21; impurity H = about 0.5; impurity B = about 0.6; impurity C = about 0.66; impurity J = about 0.7; impurity D = about 0.75; impurity F = about 1.03; impurity G = about 1.5.
System suitability:
— resolution: minimum 2.0 between the peaks due to nizatidine and impurity F in the chromatogram obtained with reference solution (c); minimum 1.5 between the peaks due to impurities A and K in the chromatogram obtained with reference solution (d).
Limits:
— correction factors: for the calculation of content, multiply the peak areas of the following impurities by the corresponding correction factor: impurity B = 1.7; impurity D = 2.3; impurity H = 0.5;
— impurities A, B, C, D, F, G, H, J, K: for each impurity, not more than 3 times the area of the principal peak in the chromatogram obtained with reference solution (a) (0.3 per cent);
— unspecified impurities: for each impurity, not more than the area of the principal peak in the chromatogram obtained with reference solution (a) (0.10 per cent);
— total: not more than 15 times the area of the principal peak in the chromatogram obtained with reference solution (a) (1.5 per cent);
— disregard limit: 0.5 times the area of the principal peak in the chromatogram obtained with reference solution (a) (0.05 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
Liquid chromatography (2.2.29) as described in the test for related substances with the following modifications.
Mobile phase: Mobile phase B, mobile phase A (35:65 V/V).
Injection: Test solution (b) and reference solution (b).
Retention time: Nizatidine = 9 min.
Calculate the percentage content of C12H21N5O2S2 taking into account the assigned content of nizatidine CRS.
IMPURITIES
Specified impurities A, B, C, D, F, G, H, J, K.
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) E, I.
A. N,N′-dimethyl-2-nitroethene-1,1-diamine,
B. (EZ)-N-methyl-1-(methylsulfanyl)-2-nitroethen-1-amine,
C. (EZ)-N-[2-[[[2-[(dimethylamino)methyl]thiazol-4-yl]methyl]sulfinyl]ethyl]-N′-methyl-2-nitroethene-1,1- diamine,
D. 2-[[[2-[(dimethylamino)methyl]thiazol-4-yl]methyl]sulfanyl]ethanamine,
E. N-[2-[[[2-[(dimethylamino)methyl]thiazol-4-yl]methyl]sulfanyl]ethyl]-2 nitroacetamide,
F. (EZ)-N-methyl-N′-[2-[[[4-[[[2-[[(EZ)-1-(methylamino)-2-nitroethenyl]amino]ethyl]sulfanyl]methyl]thiazol-2-yl]methyl]sulfanyl]ethyl]-2-nitroethene-1,1-diamine,
G. N,N′-bis[2-[[[2-[(dimethylamino)methyl]thiazol-4-yl]methyl]sulfanyl]ethyl]-2-nitroethene-1,1-diamine,
H. 2-(dimethylamino)thioacetamide,
I. N-[2-[[[2-[(dimethylamino)methyl]thiazol-4-yl]methyl]sulfanyl]ethyl]-N′-methylurea,
J. [2-[(dimethylamino)methyl]thiazol-4-yl]methanol,
K. 3-(methylamino)-5,6-dihydro-2H-1,4-thiazin-2-one oxime.
