Imipramine Hydrochloride Injection

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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Imipramine Hydrochloride Injection

» Imipramine Hydrochloride Injection is a sterile solution of Imipramine Hydrochloride in Water for Injection. It contains, in each mL, not less than 11.5 mg and not more than 13.5 mg of C₁₉H₂₄N₂ · HCl.

Packaging and storage—

Preserve in single-dose containers, preferably of Type I glass.

USP Reference standards 〈11〉—

USP Imipramine Hydrochloride RS

1 Identification—

Transfer 10 mL of Injection to a separator, add 2 mL of 2 N hydrochloric acid, extract with 10 mL of chloroform, filter, and evaporate the chloroform solution to about 2 mL. Carefully add ether until the liquid becomes turbid, heat on a steam bath to produce a clear solution, then cool, and allow to stand. Filter the crystalline precipitate, wash with ether, and dry in vacuum at 105° for 30 minutes: the precipitate so obtained responds to Identification test A under Imipramine Hydrochloride.

Bacterial Endotoxins Test 〈85〉 —

It contains not more than 5.0 USP Endotoxin Units per mg of imipramine hydrochloride.

pH 〈791〉:

between 4.0 and 5.0.

Other requirements—

It meets the requirements under Injections and Implanted Drug Products 〈1〉.

2 Assay—

Transfer an accurately measured volume of Injection, equivalent to about 25 mg of imipramine hydrochloride, to a 100-mL volumetric flask, add 0.5 N hydrochloric acid to volume, and mix. Pipet 10 mL of this solution into a separator, add 10 mL of 1 N sodium hydroxide, and extract with four 20-mL portions of ether, shaking each portion for 2 minutes and collecting the extracts in a second separator. Extract the combined ether extracts with four 20-mL portions of 0.5 N hydrochloric acid, and combine the extracts in a 250-mL beaker. Aerate this solution with nitrogen to remove residual ether, then transfer to a 100-mL volumetric flask, and rinse the beaker with 0.5 N hydrochloric acid, collecting the rinsings in the flask. Add the 0.5 N acid to volume, and mix.

Dissolve an accurately weighed quantity of USP Imipramine Hydrochloride RS in 0.5 N hydrochloric acid, and dilute quantitatively and stepwise with the same solvent to obtain a Standard solution having a known concentration of about 25 µg per mL. Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 250 nm, with a suitable spectrophotometer, using 0.5 N hydrochloric acid as the blank.

Calculate the quantity, in mg, of C₁₉H₂₄N₂ · HCl in each mL of the Injection taken by the formula:

(C/V)(Aᵤ/Aₛ)

in which

C is the concentration, in µg per mL, of USP Imipramine Hydrochloride RS in the Standard solution;

V is the volume, in mL, of Injection taken;

Aᵤ and Aₛ are the absorbances of the solution from the Injection and the Standard solution, respectively.