Primaquine Phosphate

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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1 DEFINITION

Primaquine Phosphate contains NLT 97.0% and NMT 102.0% of primaquine phosphate (C₁₅H₂₁N₃O·2H₃PO₄), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

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

B. Identification Tests—General 〈191〉, Chemical Identification Tests, Phosphate, Pyrophosphates: The residue obtained by ignition meets the requirements.

C. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

Change to read:

Procedure

Mobile phase: Acetonitrile, tetrahydrofuran, trifluoroacetic acid, and water (9:1:0.1:90)

Standard solution: 0.4 mg/mL of USP Primaquine Phosphate RS in Mobile phase.

[Note—Sonicate with intermittent shaking to dissolve, if necessary.]

System suitability stock solution: 0.4 mg/mL of USP Primaquine Related Compound A RS in Mobile phase

System suitability solution: Transfer 1.0 mL of the System suitability stock solution to a 10-mL volumetric flask, and dilute with Standard solution to volume.

Sensitivity solution: 0.2 µg/mL of USP Primaquine Phosphate RS from the Standard solution

Sample solution: 0.4 mg/mL of Primaquine Phosphate in Mobile phase.

[Note—Sonicate with intermittent shaking to dissolve, if necessary.]

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 265 nm

Column: 4.6-mm × 75-mm; 3-µm packing L7

Flow rate: 1.5 mL/min

Injection volume: 10 µL

Run time: ▲NLT▲ 3 times the retention time of primaquine

System suitability

Samples: Standard solution, System suitability solution, and Sensitivity solution

Suitability requirements

Resolution: NLT 2.5 between primaquine and primaquine related compound A, System suitability solution

Relative standard deviation: NMT 1.0% for primaquine, Standard solution

Signal-to-noise ratio: NLT 10 for the primaquine peak, Sensitivity solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of primaquine phosphate (C₁₅H₂₁N₃O·2H₃PO₄) in the portion of Primaquine Phosphate taken:

Result = (rᵤ / rₛ) × (Cₛ / Cᵤ) × 100

rᵤ = peak response of primaquine phosphate from the Sample solution

rₛ = peak response of primaquine phosphate from the Standard solution

Cₛ = concentration of USP Primaquine Phosphate RS in the Standard solution (mg/mL)

Cᵤ = concentration of Primaquine Phosphate in the Sample solution (mg/mL)

Acceptance criteria: 97.0%–102.0% on the dried basis

4 IMPURITIES

Change to read:

Organic Impurities

Mobile phase, Standard solution, System suitability solution, Sensitivity solution, Sample solution, Chromatographic system, and System suitability: Proceed as directed in the Assay.

Analysis

Sample: Sample solution

Calculate the percentage of each impurity in the portion of Primaquine Phosphate taken:

Result = (rᵢ / rₜ) × 100

rᵢ = peak response of each impurity from the Sample solution

rₜ = peak response of primaquine phosphate from the Sample solution

Acceptance criteria: See Table 1.

Disregard any impurity peak less than 0.05%.

Table 1

ᵃ 6-Methoxyquinolin-8-amine.

ᵇ 2,3-Dihydrophthalazine-1,4-dione.

ᶜ 8-[(4-Aminopentyl)amino]-6-methoxyquinoline.

ᵈ N³-(6-Methoxyquinolin-8-yl)pentane-1,3-diamine.

5 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry at 105° for 2 h.

Acceptance criteria: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed, light-resistant containers.

USP Reference Standards 〈11〉

USP Primaquine Phosphate RS

USP Primaquine Related Compound A RS

8-[(4-Aminopentyl)amino]-6-methoxyquinoline.

C₁₅H₂₁N₃O 259.35