Edition: BP 2025 (Ph. Eur. 11.6 update)
(Ph. Eur. monograph 2896)
C27H33NO10S, xC2H6O 563.6 (ethanol-free substance)
Anhydrous thiocolchicoside 602-41-5
Action and use
Muscle relaxant.
Ph Eur
DEFINITION
N-[(7S,12aRa)-3-(β-D-Glucopyranosyloxy)-1,2-dimethoxy-10-(methylsulfanyl)-9-oxo-5,6,7,9-tetrahydrobenzo[a]heptalen-7-yl]acetamide.
Content
97.0 per cent to 102.0 per cent (anhydrous substance).
It contains a variable quantity of ethanol.
CHARACTERS
Appearance
Yellow crystalline powder, hygroscopic.
Solubility
Sparingly soluble in water, practically insoluble in acetone and in ethanol (96 per cent).
mp
About 208 °C.
IDENTIFICATION
Infrared absorption spectrophotometry (2.2.24).
Comparison thiocolchicoside crystallised from ethanol CRS.
TESTS
Appearance of solution
The solution is clear (2.2.1).
Dissolve 0.100 g in methanol R and dilute to 10 mL with the same solvent.
Specific optical rotation (2.2.7)
-600 to -570 (anhydrous substance).
Dissolve 0.500 g in water R and dilute to 100.0 mL with the same solvent.
Related substances
Liquid chromatography (2.2.29). Carry out the test protected from light.
Test solution (a): Dissolve 20.0 mg of the substance to be examined in methanol R and dilute to 20.0 mL with the same solvent.
Test solution (b): Dilute 1.0 mL of test solution (a) to 10.0 mL with methanol R.
Reference solution (a): Dilute 1.0 mL of test solution (a) to 100.0 mL with methanol R. Dilute 2.0 mL of this solution to 10.0 mL with methanol R.
Reference solution (b): Dissolve 5 mg of thiocolchicoside for system suitability CRS (containing impurities D, E, G, H, K and L) in methanol R and dilute to 5 mL with the same solvent.
Reference solution (c): Dissolve 20.0 mg of thiocolchicoside hydrate CRS in methanol R and dilute to 20.0 mL with the same solvent. Dilute 1.0 mL of the solution to 10.0 mL with methanol R.
Column:
size: l = 0.10 m, Ø = 2.1 mm;
stationary phase: end-capped ethylene-bridged phenylsilyl silica gel for chromatography (hybrid material) R (1.7 µm);
temperature: 25 °C.
Mobile phase:
mobile phase A: dissolve 0.22 g of ammonium formate R in 350 mL of water for chromatography R and mix with 25 mL of tetrahydrofuran R;
mobile phase B: dilute 45 µL of anhydrous formic acid R in 900 mL of acetonitrile R and mix with 100 mL of tetrahydrofuran R;
Gradient table:
| Time (min) | Mobile phase A (% V/V) | Mobile phase B (% V/V) |
|---|---|---|
| 0 – 2 | 99 | 1 |
| 2 – 6 | 99 → 92 | 1 → 8 |
| 6 – 7.5 | 92 → 70 | 8 → 30 |
| 7.5 – 8.8 | 70 → 50 | 30 → 50 |
| 8.8 – 9.2 | 50 → 2 | 50 → 98 |
| 9.2 – 10 | 2 | 98 |
Flow rate: 0.4 mL/min.
Detection: Spectrophotometer at 370 nm.
Injection: 1.0 µL of test solution (a) and reference solutions (a) and (b).
Identification of impurities: Use the chromatogram supplied with thiocolchicoside for system suitability CRS and the chromatogram obtained with reference solution (b) to identify the peaks due to impurities D, E, H and L.
Relative retention (with reference to thiocolchicoside, retention time ≈ 6 min): impurity D = about 0.2; impurity H = about 0.4; impurity E = about 1.05; impurity L = about 1.11.
System suitability:
signal-to-noise ratio: minimum 50 for the principal peak in the chromatogram obtained with reference solution (a);
peak-to-valley ratio: minimum 1.5, where Hp = height above the baseline of the peak due to impurity E and Hv = height above the baseline of the lowest point of the curve separating this peak from the peak due to thiocolchicoside in the chromatogram obtained with reference solution (b).
Calculation of percentage contents:
correction factor: multiply the peak areas of the following impurities by the corresponding correction factor:
impurity D = 1.7
impurity H = 2.8
for each impurity, use the concentration of the substance to be examined in reference solution (a).
Limits:
impurity D: maximum 0.4 per cent;
impurities E, H: for each impurity, maximum 0.3 per cent;
unspecified impurities: for each impurity, maximum 0.10 per cent;
total: maximum 1.0 per cent;
reporting threshold: 0.05 per cent; disregard the peak due to impurity L.
Ethanol (2.4.24)
Maximum 1.5 per cent.
Water (2.5.12)
Maximum 2.5 per cent, determined on 0.500 g.
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 modification.
Injection: Test solution (b) and reference solution (c).
Calculate the percentage content of C27H33NO10S taking into account the assigned content of thiocolchicoside hydrate CRS.
STORAGE
In an airtight container, protected from light.
IMPURITIES
Specified impurities: D, E, H.
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, C, G, J, K, L.
