Dipyridamole 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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» Dipyridamole Injection is a sterile solution of Dipyridamole in Water for Injection. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of dipyridamole (C₂₄H₄₀N₈O₄) 

1 Packaging and storage

Preserve as described in Packaging and Storage Requirements (659), Injection Packaging. Protect from light, and avoid freezing.

2 USP REFERENCE STANDARDS (11)-

USP Dipyridamole RS

3 Identification-

A: THIN-LAYER CHROMATOGRAPHIC IDENTIFICATION TEST (201)-

Test solution-Use the Injection.

Standard solution: 5 mg per mL in a mixture of methanol, water, and 0.1 N hydrochloric acid (5:4:1).

Developing solvent system: a mixture of butyl alcohol, water, and glacial acetic acid (34:10:5).

Procedure-Proceed as directed in the chapter. Locate the yellow spots on the plate: the R, value of the principal spot obtained from the Test solution corresponds to that of the principal spot obtained from the Standard solution. Spray the plate lightly with a spray reagent prepared as follows. Transfer 1 g of iodine and 3 g of potassium iodide to a 100-mL volumetric flask. Add 10 mL of alcohol to dissolve (heat gently). Add 20 mL of 2N sulfuric acid, dilute with water to volume, and mix. Store in a dark place. Observe the plate, and locate the brown spots: the R, value of the principal spot obtained from the Test solution corresponds to that of the principal spot obtained from the Standard solution.

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

4 BACTERIAL ENDOTOXINS TEST (85)

It contains not more than 8.8 USP Endotoxin Units per mg of dipyridamole.

PH (791): between 2.2 and 3.2.

5 Chromatographic purity-

[NOTE-Protect dipyridamole solutions from exposure to light.]

Mobile phase and Chromatographic system-Proceed as directed in the Assay.

Test solution-Use the Assay preparation prepared as directed in the Assay.

Procedure-Inject a volume (about 10 µL) of the Test solution into the chromatograph, record the chromatogram, and measure the peak responses. Calculate the percentage of each impurity in the portion of Injection taken by the formula:

                100(r_i/г_S)

in which r_i is the peak response for each impurity; and г_S is the sum of the responses of all of the peaks: not more than 2.0% of any individual impurity is found; and not more than 4.5% of total impurities is found.

6 Other requirements-

It meets the requirements under Injections and Implanted Drug Products (1).

7 Assay-

[NOTE-Protect dipyridamole solutions from exposure to light.]

Acetate buffer-Dissolve a quantity of sodium acetate in water to obtain a concentration of about 6.8 mg per mL. Adjust with acetic acid to a pH of 5.1 ± 0.1.

Mobile phase-Prepare a filtered and degassed mixture of methanol and Acetate buffer (65:35). Make adjustments if necessary (see System Suitability under Chromatography (621)).

Standard preparation-Dissolve an accurately weighed quantity of USP Dipyridamole RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a known concentration of about 1.0 mg per mL.

Assay preparation-Transfer an accurately measured volume of Injection, equivalent to about 25 mg of dipyridamole, to a 25-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Chromatographic system (see CHROMATOGRAPHY (621))-The liquid chromatograph is equipped with a 276-nm detector and a 3.9-mm x 30-cm column that contains packing L1. The flow rate is about 1.0 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 2000 theoretical plates; the tailing factor is not greater than 1.7; and the relative standard deviation for replicate injections is not greater than 2.0%.

Procedure-Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of dipyridamole (C₂₄H₄₀N₈O₄) in the portion of Injection taken by the formula:

                25C(r_U/r_S)

in which C is the concentration, in mg per mL, of USP Dipyridamole RS in the Standard preparation; and r_U and r_S are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.