Disopyramide Phosphate
;)
2-Pyridineacetamide,a-[2-[bis(1-methylethyl)amino]ethyl]-a-phenyl-,(±)-,phosphate (1:1).
(±)-a-[2-(Diisopropylamino)ethyl]-a-phenyl-2-pyridineacetamide phosphate (1:1) [22059-60-5].
»Disopyramide Phosphate contains not less than 98.0percent and not more than 102.0percent of C21H29N3O·H3PO4,calculated on the dried basis.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
A:
Infrared Absorption á197Mñ.
B:
Asolution (1in 200)responds to the tests for Phosphate á191ñ.
pHá791ñ:
between 4.0and 5.0in a solution (1in 20).
Loss on drying á731ñ—
Dry it at 105
for 4hours:it loses not more than 0.5%of its weight.
for 4hours:it loses not more than 0.5%of its weight.
Heavy metals,Method IIá231ñ:
0.002%.
Chromatographic purity—
Standard solutions—
Prepare solutions Aand Bof USP Disopyramide Phosphate RSin methanol having concentrations of about 50and 100µg per mL,respectively.
Test solution—
Prepare a solution of Disopyramide Phosphate in methanol having a concentration of about 10mg per mL.
Procedure—
Separately apply 10-µLportions of the Standard solutions Aand Band the Test solutionto a suitable thin-layer chromatographic plate (see Chromatography á621ñ),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 RFvalue of the principal spot obtained from the Test solutioncorresponds to that obtained from Standard solution B.Estimate the levels of any additional spots observed in the chromatogram of the Test preparationby comparison with the principal spots in the chromatograms of Standard solutions Aand B:the sum of the intensities of any additional spots observed is not greater than that obtained from Standard solution B(equivalent to 1%).
Organic volatile impurities,Method Iá467ñ:
meets the requirements.
Assay—
Dissolve about 160mg of Disopyramide Phosphate,accurately weighed,in 50mLof glacial acetic acid TS,and titrate with 0.1Nperchloric acid VS,determining the endpoint potentiometrically.Perform a blank determination,and make any necessary correction.Each mLof 0.1Nperchloric acid is equivalent to 21.87mg of C21H29N3O·H3PO4.
Auxiliary Information—
Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate
Expert Committee:(PA5)Pharmaceutical Analysis 5
USP28–NF23Page 677
Phone Number:1-301-816-8305