» Inamrinone contains not less than 98.0 percent and not more than 102.0 percent of C10H9N3O, calculated on the anhydrous basis.
CautionInamrinone is a cardiotonic agent.
Packaging and storage Preserve in well-closed containers, protected from light. Store at 25, excursions permitted between 15 and 30.
B: Ultraviolet Absorption 197U
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: A237 / A318 do not differ by more than 3.0%.
Water, Method I 921: not more than 1.0%.
Residue on ignition 281: not more than 0.2%.
Heavy metals, Method II 231: 0.002%.
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 Mobile phase 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. [noteUse 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: not more than 0.2% of any individual impurity is found; and the sum of all impurities is not more than 1.0%.
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.
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USP32NF27 Page 2621Pharmacopeial Forum: Volume No. 29(5) Page 1507