Disopyramide Phosphate Capsules
Action and use
Class I antiarrhythmic.
Definition
Disopyramide Phosphate Capsules contain Disopyramide Phosphate.
Content of disopyramide, C21H29N3O
92.5 to 107.5% of the stated amount.
Identification
TESTS
Dissolution
Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules, Appendix XII B1.
After 45 minutes withdraw a 10 mL sample of the medium and measure the absorbance of the filtered sample, suitably diluted with the dissolution medium if necessary, at the maximum at 262 nm, Appendix II B, using water in the reference cell.
Calculate the total content of disopyramide, C21H29N3O, in the medium taking 125 as the value of A(1%, 1 cm) at the maximum at 262 nm.
Related substances
Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
1 volume of 18m ammonia, 30 volumes of acetone and 30 volumes of cyclohexane.
Any secondary spot in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (0.5%).
Assay
To a quantity of the mixed contents of 20 capsules containing the equivalent of 40 mg of disopyramide, add 40 mL of 0.05m methanolic sulfuric acid, shake for 15 minutes, dilute to 100 mL with the same solvent and filter. Dilute 5 mL of the filtrate to 100 mL with 0.05m methanolic sulfuric acid and measure the absorbance of the resulting solution at the maximum at 269 nm, Appendix II B. Calculate the content of C21H29N3O taking 125 as the value of A(1%, 1 cm) at the maximum at 269 nm.
Labelling
The quantity of active ingredient is stated in terms of the equivalent amount of disopyramide.