Determined by liquid chromatography.
Test solution: When tablets are film-coated, shake 20 tablets with 50ml of 0.1 M HCl until completely disintegrated, add 100ml of methanol, shake for 30 minutes, dilute the suspension to 200.0ml with methanol, shake for 30 minutes, dilute the suspension to 200.0ml with methanol, centrifuge and dilute a volume of the supernatant liquid equivalent to 25mg of Amitriptyline HCl to 100.0ml with methanol (50 per cent).
When tablets are sugar-coated, weigh and powder 20 tablets. Weigh a quantity of the powder containing 50mg of Amitriptyline HCl, shake with 50ml of 0.1 M Hcl for 30 minutes, add 100ml of methanol, shake for 30 minutes, dilute the mixture to 200.0ml with water, centrifuge and use the supernatant liquid.
Reference solution: Dissolve 50mg of amitriptyline HCl reference standard in 10ml of methanol and dilute to 200.0ml with methanol (50 per cent).
Chromatographic system:
- A stainless steel column 20cmX4.6mm packed with octadecylsilane bonded to porous silica or ceramic microparticles (10µm),
- Mobile phase: 0.03 M sodium hexanesulphonate in a mixture of equal volumes of acetonitrile and water, adjusted to pH 4.5 with G.A.A.
- Flow rate: 2ml per minute,
- Spectrophotometer set at 239nm,
- Injection volume: 20µl
Alternative Method: By UV Spectrophotometer
Test Solution: Weigh and powder 20 tablets. Weight sample equivalent to 50mg of Amitriptyline HCl 100ml volumetric flask add 20ml 0.1M HCl into it and sonicate to dissolve the test sample. Make up to mark with 0.1 M HCl. Filter and dilute 1ml of this solution to 50ml in 0.1 M HCl.
Reference Solution: Weigh 50mg of reference standard of Amitriptyline HCl in 100ml of volumetric flask. Add 20ml 0.1 M HCl into it and sonicate to dissolve. Make up to mark with 0.1 M HCl. Dilute 1ml of this solution to 50ml with same solvent.
Check Absorbance of test as well as reference standard at about 239nm in UV Spectrophotometer.
Calculate the content of Amitriptyline HCl in the tablets.
Formula:
Area of Test STD Wt.(mg) 1 100 50 Potency
—————–X————–X——-X—————X——–X———-X Average wt.
Area of STD 100 50 Test Wt.(mg) 1 100
Acceptance criteria: 90.0%-110.0%
