Inamrinone

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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» Inamrinone contains not less than 98.0 percent and not more than 102.0 percent of C₁₀H₉N₃O, calculated on the anhydrous basis.

[Caution—Inamrinone is a cardiotonic agent.]

Packaging and storage—

Preserve in well-closed containers, protected from light. Store at 25°, excursions permitted between 15° and 30°.

USP Reference standards 〈11〉—

USP Inamrinone RS

USP Inamrinone Related Compound A RS

5-Carboxamide[3,4′-bipyridin]-6(1H)-one

C₁₁H₉N₃O₂ 215.21

1 Identification—

Change to read:

A: ▲Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K▲ (CN 1-May-2020).

Change to read:

B: ▲Spectroscopic Identification Tests 〈197〉, Ultraviolet-Visible Spectroscopy: 197U▲ (CN 1-May-2020)—

pH 8.9 Buffer—Dissolve 107 g of dibasic sodium phosphate in water, adjust, if necessary, with 0.1 M sodium hydroxide or 0.1 M phosphoric acid to a pH of 8.9 ± 0.1, dilute with water to 1000 mL, and mix.

Solution: 6 µg per mL, prepared as follows. Dissolve 100 mg in 20 mL of water and 1.0 mL of 1 N hydrochloric acid in a 100-mL volumetric flask, dilute with water to volume, and mix. Dilute 5.0 mL of this solution to 50.0 mL with 0.01 N hydrochloric acid, mix, and transfer 3.0 mL to a 50-mL volumetric flask. Dilute with pH 8.9 Buffer to volume, and mix.

Ratio: Aᵤ/Aₛ do not differ by more than 3.0%.

Water Determination, Method I 〈921〉: not more than 1.0%.

Residue on ignition 〈281〉: not more than 0.2%.

Chromatographic purity—

Solution A—Dissolve 6.8 g of monobasic potassium phosphate in 1000 mL of water, add 2 mL of triethylamine, and adjust with phosphoric acid to a pH of 2.5. Filter and degas. Make adjustments if necessary (see System Suitability under Chromatography 〈621〉).

Solution B—Prepare a mixture of Solution A and acetonitrile (85:15).

Mobile phase—Use variable mixtures of Solution A and Solution B as directed for Chromatographic system.

Diluting solution—Dissolve 0.25 g of sodium metabisulfite in 1000 mL of Solution A.

Standard stock solution—Dissolve an accurately weighed quantity of USP Inamrinone RS in Diluting solution to obtain a solution having a known concentration of about 2 mg per mL.

Standard solution—Dilute a suitable volume of Standard stock solution quantitatively, and stepwise if necessary, with Diluting solution to obtain a solution having a known concentration of 4 µg of USP Inamrinone RS per mL.

System suitability solution—Prepare a solution of USP Inamrinone Related Compound A RS in Diluting solution having a concentration of 2 mg per mL. Transfer 5.0 mL of this solution and 5.0 mL of the Standard stock solution to a 50-mL volumetric flask, dilute with Diluting solution to volume, and mix.

Test solution—Transfer about 100 mg of Inamrinone, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with Diluting solution to volume, and mix.

[Note—Use this solution within 1 hour after preparation.]

Chromatographic system (see Chromatography 〈621〉)—

The liquid chromatograph is equipped with a 315-nm detector and a 4.0-mm × 25-cm analytical column that contains packing L1 and is fitted with a guard column that contains packing L1. The flow rate is about 1.0 mL per minute. The chromatograph is programmed as follows.

Allow the system to equilibrate at the original conditions before making subsequent injections. Chromatograph 15 µL of the System suitability solution, record the chromatograms, and measure the peak responses as described for Procedure: the relative retention times are 0.6 for inamrinone and 1.0 for inamrinone related compound A; and the resolution, R, between inamrinone and inamrinone related compound A is not less than 4.0. Chromatograph about 15 µL of the Standard solution, and record the peak responses for inamrinone as directed for Procedure: the relative standard deviation for replicate injections is not more than 5.0%.

Procedure—

Separately inject equal volumes (about 15 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms allowing the Test solution to elute for not less than five times the retention times of inamrinone, and measure the areas of all the peaks observed in the chromatogram of the Test solution.

Calculate the percentage of each impurity in the portion of Inamrinone taken by the formula:

5000(C/W)(rᵢ/rₛ)

in which C is the concentration, in mg per mL, of USP Inamrinone RS in the Standard solution; W is the weight, in mg, of inamrinone taken for the Test solution; rᵢ is the response of each impurity peak; and rₛ is the mean response for the Standard solution.

Acceptance criteria: not more than 0.2% of any individual impurity is found; and the sum of all impurities is not more than 1.0%.

2 Assay—

Weigh accurately about 500 mg of Inamrinone, and proceed as directed under Nitrite Titration 〈451〉. Each mL of 0.1 M sodium nitrite is equivalent to 18.72 mg of C₁₀H₉N₃O.