Procainamide Tablets

General Notices

Action and use

Class I antiarrhythmic.

Definition

Procainamide Tablets contain Procainamide Hydrochloride.

The tablets comply with the requirements stated under Tablets and with the following requirements.

Content of procainamide hydrochloride, C13H21N3O,HCl

95.0 to 105.0% of the stated amount.

Identification

A. Shake a quantity of the powdered tablets containing 0.25 g of Procainamide Hydrochloride with 25 mL of water, make alkaline with 5m sodium hydroxide and extract with two 5 mL quantities of chloroform. Filter the combined extracts through anhydrous sodium sulfate, evaporate the filtrate to dryness using a rotary evaporator and dissolve the residue in 5 mL of chloroform. The infrared absorption spectrum of the resulting solution, Appendix II A, is concordant with the reference spectrum of procainamide (RS 288).
B. Triturate a quantity of the powdered tablets containing 2 g of Procainamide Hydrochloride with 20 mL of water and filter. Reserve 10 mL of the filtrate for test C. To the remainder add 10 mL of 5m sodium hydroxide and extract with 10 mL of chloroform. Add 10 mL of toluene to the extract, dry over anhydrous sodium sulfate and filter. Mix the filtrate with 5 mL of dry pyridine, add 1 mL of benzoyl chloride drop wise, heat on a water bath for 30 minutes and pour into 100 mL of 2.5m sodium hydroxide. Extract with 10 mL of ether, wash the extract with 20 mL of water, dilute with 30 mL of ether and allow to crystallise. The melting point of the crystals, after recrystallisation from ethanol (45%), is about 186°, Appendix V A.
C. 10 mL of the filtrate reserved in test B yields the reactions characteristic of chlorides, Appendix VI.

Related substances

Comply with the test described under Procainamide Injection using the following solutions. For solution (1) shake a quantity of the powdered tablets containing 0.4 g of Procainamide Hydrochloride with 20 mL of methanol (90%) for 15 minutes and filter. For solution (2) dilute 1 volume of solution (1) to 100 volumes with methanol.

Assay

Weigh and powder 20 tablets. To a quantity of the powder containing 0.5 g of Procainamide Hydrochloride in a stoppered flask add 100 mL of 6m hydrochloric acid, shake for 15 minutes and titrate with 0.1m sodium nitrite VS, using ferrocyphen solution as indicator, until a violet colour is produced that is stable for not less than 3 minutes. Repeat the operation without the powdered tablets. The difference between the titrations represents the amount of sodium nitrite required. Each mL of 0.1m sodium nitrite VS is equivalent to 27.18 mg of C13H21N3O,HCl.