Disopyramide Phosphate
(dye'' soe pir' a mide fos' fate).
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C21H29N3O·H3PO4 437.47

2-Pyridineacetamide, -[2-[bis(1-methylethyl)amino]ethyl]--phenyl-, (±)-, phosphate (1:1).
(±)--[2-(Diisopropylamino)ethyl]--phenyl-2-pyridineacetamide phosphate (1:1) [22059-60-5].
» Disopyramide Phosphate contains not less than 98.0 percent and not more than 102.0 percent of C21H29N3O·H3PO4, calculated on the dried basis.
Packaging and storage— Preserve in tight, light-resistant containers.
USP Reference standards 11
USP Disopyramide Phosphate RS Click to View Structure
B: A solution (1 in 200) meets the requirements of the tests for Phosphate 191.
pH 791: between 4.0 and 5.0 in a solution (1 in 20).
Loss on drying 731 Dry it at 105 for 4 hours: it loses not more than 0.5% of its weight.
Chromatographic purity—
Standard solutions— Prepare solutions A and B of USP Disopyramide Phosphate RS in methanol having concentrations of about 50 and 100 µg per mL, respectively.
Test solution— Prepare a solution of Disopyramide Phosphate in methanol having a concentration of about 10 mg per mL.
Procedure— Separately apply 10-µL portions of Standard solutions A and B and the Test solution to a suitable thin-layer chromatographic plate (see Chromatography 621), coated with a 0.25-mm layer of chromatographic silica gel. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of toluene, dehydrated alcohol, and ammonium hydroxide (170:28:2) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, allow to air-dry, and spray with potassium bismuth iodide TS: the RF value of the principal spot obtained from the Test solution corresponds to that obtained from Standard solution B. Estimate the levels of any additional spots observed in the chromatogram of the Test solution by comparison with the principal spots in the chromatograms of Standard solutions A and B: the sum of the intensities of any additional spots observed is not greater than that obtained from Standard solution B (equivalent to 1%).
Assay— Dissolve about 160 mg of Disopyramide Phosphate, accurately weighed, in 50 mL of glacial acetic acid, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 21.87 mg of C21H29N3O·H3PO4.
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Monograph Sujatha Ramakrishna, Ph.D.
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(SM22010) Monographs - Small Molecules 2
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