Hydralazine Tablets

General Notices

Action and use

Vasodilator; treatment of hypertension.

Definition

Hydralazine Tablets contain Hydralazine Hydrochloride.

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

Content of hydralazine hydrochloride, C8H8N4,HCl

95.0 to 105.0% of the stated amount.

Identification

A. Dissolve a quantity of the powdered tablets containing 0.1 g of Hydralazine Hydrochloride in 10 mL of water, make alkaline with 2 mL of 5m ammonia and extract with two 10-mL quantities of chloroform. Combine the chloroform extracts and evaporate to dryness. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of hydralazine (RS 176).
B. Shake a quantity of the powdered tablets containing 25 mg of Hydralazine Hydrochloride with 30 mL of methanol for 15 minutes, add sufficient methanol to produce 50 mL and filter. Dilute 1 volume of the filtrate to 50 volumes with water. The light absorption of the resulting solution, Appendix II B, in the range 230 to 350 nm exhibits four maxima, at 240, 260, 305 and 315 nm.
C. Extract a quantity of the powdered tablets containing 0.1 g of Hydralazine Hydrochloride with two 25-mL quantities of methanol, filter the combined extracts and evaporate to dryness. To 5 mL of a 1% w/v solution of the residue in methanol add 5 mL of a 2% w/v solution of 2-nitrobenzaldehyde in ethanol (96%). An orange precipitate is produced.

TEST

Hydrazine

Carry out the method for thin-layer chromatography, Appendix III A, using a silica gel precoated plate (Merck silica gel 60 plates are suitable) and as the mobile phase the upper layer obtained by shaking together 20 volumes of 13.5m ammonia, 20 volumes of ethyl acetate and 80 volumes of hexane and allowing to separate. Apply separately to the plate 40 µL of each of the following solutions. For solution (1) extract a quantity of the powdered tablets containing 50 mg of Hydralazine Hydrochloride with 10 mL of 0.1m methanolic hydrochloric acid; to 2 mL add 1 mL of a 2% w/v solution of salicylaldehyde in methanol and 0.1 mL of hydrochloric acid, centrifuge and use the supernatant liquid. Prepare solution (2) in the same manner, but using 2 mL of a 0.00025% w/v solution of hydrazine sulfate in 0.1m methanolic hydrochloric acid in place of the solution of the substance being examined. After removal of the plate, allow it to dry in air and spray with dimethylaminobenzaldehyde solution R1. Any spot corresponding to hydrazine in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (0.05%).

Assay

Weigh and powder 20 tablets. To a quantity of the powder containing 50 mg of Hydralazine Hydrochloride add 50 mL of water and shake for 20 minutes. Add 60 mL of hydrochloric acid and titrate with 0.025m potassium iodate VS determining the end point potentiometrically using platinum and calomel electrodes. Each mL of 0.025m potassium iodate VS is equivalent to 4.916 mg of C8H8N4,HCl.

Storage

Hydralazine Tablets should be protected from light.