Disopyramide phosphate is an antiarrhythmic drug available for oral administration in immediate-release capsules containing 100 mg or 150 mg of disopyramide base, present as the phosphate. The base content of the phosphate salt is 77.6%. The structural formula of disopyramide phosphate is:
|α-[2-(diisopropylamino) ethyl]-α-phenyl- 2-pyridineacetamide phosphate|
Disopyramide phosphate is freely soluble in water, and the free base (pKa 10.4) has an aqueous solubility of 1 mg/ml. The chloroform:water partition coefficient of the base is 3.1 at pH 7.2.
Disopyramide phosphate is a racemic mixture of d- and l- isomers. This drug is not chemically related to other antiarrhythmic drugs.
Inactive ingredients of disopyramide phosphate include corn starch, edible ink, FD&C Red No. 3, FD&C Yellow No. 6, gelatin, lactose, talc, and titanium dioxide; the 150-mg capsule also contains FD&C Blue No. 1.