Chemical stability of hydralazine hydrochloride after reconstitution in 0.9% sodium chloride injection or 5% dextrose injection for infusion.

The chemical stability of hydralazine hydrochloride (0.2 mg/mL) in 0.9% sodium chloride injection and in 5% dextrose injection stored in a polyvinylchloride bags at 25 deg C was studied by means of a stability-indicating high-performance liquid chromatographic assay method. The concentrations of the drug were directly related to peak heights, and the percent relative standard deviation, based on five injections, was 1.2. The excipients present in the injection did not interfere with the assay procedure. The products of decomposition separated from the intact drug. In 5% dextrose injection, the loss in potency was 5% after less than 1 hour of storage and more than 40% after 1 day of storage at room temperature. The pH value of the injection decreased from 4.0 to 3.6 after 1 day. In 0.9% sodium chloride injection, the loss in potency after 2 days of storage at room temperature was 8%, and the pH value had decreased from 4.9 to 4.1. The physical appearance of the injection did not change.