Praziquantel

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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C₁₉H₂₄N₂O₂      312.41

4H-Pyrazino[2,1-a]isoquinolin-4-one, 2-(cyclohexylcarbonyl)-1,2,3,6,7,11b-hexahydro-;

2-(Cyclohexylcarbonyl)-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinolin-4-one CAS RN®: 55268-74-1; UNII: 6490C9U457.

1 DEFINITION

Praziquantel contains NLT 98.5% and NMT 101.0% of praziquantel (C₁₉H₂₄N₂O₂), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

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

B. 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

Procedure

Mobile phase: Acetonitrile and water (60:40)

Standard solution: 0.18 mg/mL of USP Praziquantel RS in Mobile phase

Sample solution: 0.18 mg/mL of Praziquantel in Mobile phase

3.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 210 nm

Column: 4-mm × 25-cm; 10-µm packing L1

Flow rate: 1.5 mL/min

Injection volume: 10 µL

3.2 System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 1.5

Relative standard deviation: NMT 1.0%

3.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of praziquantel (C₁₉H₂₄N₂O₂) in the portion of Praziquantel taken:

Result = (r_U /r_S ) × (C_S /C_U ) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of USP Praziquantel RS in the Standard solution (mg/mL)

C_U = concentration of Praziquantel in the Sample solution (mg/mL)

Acceptance criteria: 98.5%–101.0% on the dried basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.1%

4.1 Limit of Phosphate

Solution A: Dissolve 250 mg of cupric sulfate and 4.5 g of ammonium acetate in sufficient 2 N acetic acid to obtain 100 mL of solution. Solution B: 30 mg/mL of ammonium molybdate

Solution C: Grind in a mortar 5 g of sodium sulfite, 94.3 g of sodium metabisulfite, and 700 mg of 4-amino-3-hydroxy-1-naphthalenesulfonic acid. Dissolve 1.5 g of this mixture in 10 mL of water, heating gently if necessary. Use this solution only when freshly prepared. Standard stock solution: 100 µg/mL of phosphate (PO₄)³⁻ prepared as follows. Dissolve 143.3 mg of dried monobasic potassium phosphate in water to make 1000 mL of solution.

Standard solution: 5 µg/mL of phosphate (PO₄)³⁻ from the Standard stock solution

Sample solution: 10 mg/mL of Praziquantel, prepared as follows. Add 30 mL of water to 500 mg of sample, and heat to boiling. Allow to cool, and filter, collecting the filtrate in a 50-mL volumetric flask. Wash the filter with water, collect the washings in the volumetric flask, and dilute with water to volume.

Analysis: Treat 10 mL of the Standard solution and 10 mL of the Sample solution as follows. To each, add 5 mL of Solution A, 2 mL of Solution B, 1 mL of Solution C, and 1 mL of perchloric acid solution (3 in 100); mix; and allow to stand for 15 min.

Acceptance criteria: The Sample solution does not have a blue color that is darker than that of the Standard solution (0.05%).

4.2 Organic Impurities

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

Standard solution: 0.04 mg/mL each of USP Praziquantel Related Compound A RS, USP Praziquantel Related Compound B RS, and USP Praziquantel Related Compound C RS in Mobile phase

Sample solution: 20 mg/mL of Praziquantel in Mobile phase

Analysis

Samples: Standard solution and Sample solution

Calculate the percentages of praziquantel related compound A, praziquantel related compound B, or praziquantel related compound C in the portion of Praziquantel taken:

Result = (r_U /r_S ) × (C_S /C_U ) × 100

r_U = peak response of praziquantel related compound A, praziquantel related compound B, or praziquantel related compound C from the Sample solution

r_S = peak response of praziquantel related compound A, praziquantel related compound B, or praziquantel related compound C from the Standard solution

C_S = concentration of USP Praziquantel Related Compound A RS, USP Praziquantel Related Compound B RS, or USP Praziquantel Related Compound C RS in the Standard solution (mg/mL)

C_U = concentration of Praziquantel in the Sample solution (mg/mL)

Acceptance criteria: See Table 1.

Table 1

a 2-Benzoyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino [2,1-a]isoquinolin-4-one.

b 2-(Cyclohexylcarbonyl)-2,3,6,7-tetrahydro-4H-pyrazino [2,1-a]isoquinolin-4-one.

c 2-(N-Formylhexahydrohippuroyl-1,2,3,4-tetrahydroisoquinolin-1-one.

5 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry a sample in a vacuum at a pressure not exceeding 5 mm of mercury at 50° over phosphorus pentoxide for 2 h.

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

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

USP Reference Standards 〈11〉

USP Praziquantel RS

USP Praziquantel Related Compound A RS

2-Benzoyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino [2,1-a]isoquinolin-4-one.

C₁₉H₁₈N₂O₂ 306.37

USP Praziquantel Related Compound B RS

2-(Cyclohexylcarbonyl)-2,3,6,7-tetrahydro-4H-pyrazino [2,1-a]isoquinolin-4-one.

C₁₉H₂₂N₂O₂ 310.40

USP Praziquantel Related Compound C RS

2-(N-Formylhexahydrohippuroyl-1,2,3,4-tetrahydroisoquinolin-1-one.

C₁₉H₂₂N₂O₄ 342.39