Procainamide Hydrochloride Injection, USP is a sterile, nonpyrogenic solution of procainamide hydrochloride in water for injection. Each milliliter of the 2 mL vial contains procainamide hydrochloride 500 mg; methylparaben 1 mg and sodium metabisulfite 1.8 mg added in water for injection. Each milliliter of the 10 mL vial contains procainamide hydrochloride 100 mg; methylparaben 1 mg and sodium metabisulfite 0.8 mg added in water for injection. In both formulations, the solution may contain hydrochloric acid and/or sodium hydroxide for pH adjustment. pH 5.0 (4.0 to 6.0). Headspace nitrogen gassed.
Procainamide Hydrochloride Injection is intended for intravenous or intramuscular administration.
Procainamide hydrochloride, a Group 1A cardiac antiarrhythmic drug, is ρ-amino-N-[2-(diethylamino) ethyl] benzamide mono-hydrochloride. It has the following structural formula:
*(locus for acetylation to N-acetyl procainamide).
It differs from procaine which is the p-aminobenzoyl ester of 2-(diethylamino)-ethanol. Procainamide as the free base has a pKa of 9.23; the monohydrochloride is very soluble in water.