USP Monographs: Praziquantel

Packaging and storage—

Preserve in well-closed, light-resistant containers.

Dry it in vacuum at a pressure not exceeding 5 mm of mercury at 50over phosphorus pentoxide for 2 hours: it loses not more than 0.5% of its weight.

Phosphate—

Cupric sulfate solution—

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.

4-Amino-3-hydroxy-1-naphthalenesulfonic acid solution—

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 solution—

Dissolve 143.3 mg of dried monobasic potassium phosphate in water to make 1000 mL of solution. Transfer 5.0 mL of this solution to a 100-mL volumetric flask, dilute with water to volume, and mix. This solution contains the equivalent of 5 µg of phosphate (PO

4

) in each mL.

Test solution—

Add 30 mL of water to 500 mg of specimen, and heat to boiling. Allow to cool, and filter, collecting the filtrate in a 50-mL volumetric flask. Wash the filter with water, collecting the washings in the volumetric flask, dilute with water to volume, and mix.

Procedure—

Treat 10 mL of

Test solution

and 10 mL of

Standard solution

as follows. To each add 5 mL of

Cupric sulfate solution

, 2 mL of ammonium molybdate solution (3 in 100), 1 mL of

4-Amino-3-hydroxy-1-naphthalenesulfonic acid solution

, and 1 mL of perchloric acid solution (3 in 100), mix, and allow to stand for 15 minutes: the

Test solution

does not have a blue color that is darker than that of the

Standard solution

(0.05%).