Amprolium Oral Solution

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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Amprolium Oral Solution

Amprolium Oral Solution contains not less than 93.0 percent and not more than 107.0 percent of the labeled amount of amprolium (C₁₄H₁₉ClN₄·HCl).

Packaging and storage— Preserve in tight containers, protected from light. Store at a temperature between 5° and 30°, in a dry place.

Labeling— Label it to indicate that it is for veterinary use only.

USP Reference standards 〈11〉—

USP Amprolium RS

Change to read:

Identification, ▲Spectroscopic Identification Tests 〈197〉, Ultraviolet-Visible Spectroscopy: 197U▲ (CN 1-May-2020) —

Solution: 10 µg per mL, filtered.

Medium: 0.1 N hydrochloric acid.

pH 〈791〉: between 2.5 and 3.0.

1 Assay—

Mobile phase— To 4.5 g of sodium 1-hexanesulfonate add 1500 mL of water, 400 mL of methanol, and 100 mL of acetonitrile, mix, and allow to cool to room temperature. Adjust with phosphoric acid to a pH of 5.1, and pass through a filter having a 0.5-µm or finer porosity. Make adjustments if necessary (see System Suitability under Chromatography 〈621〉).

Standard preparation— Quantitatively dissolve an accurately weighed quantity of USP Amprolium RS in water to obtain a solution having a known concentration of about 0.5 mg per mL.

Assay preparation— Transfer an accurately measured volume of Oral Solution, equivalent to about 960 mg of amprolium, to a 100-mL volumetric flask, dilute with water to volume, and mix. Transfer 5.0 mL of this stock solution to a second 100-mL volumetric flask, dilute with water to volume, and mix.

Chromatographic system (see Chromatography 〈621〉)—

The liquid chromatograph is equipped with a 268-nm detector and a 3.9-mm × 30-cm column that contains packing L11. The column is maintained at a constant temperature of about 45°. The flow rate is about 1 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the tailing factor is not more than 1.5; and the relative standard deviation for replicate injections is not more 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 peak areas for amprolium. Calculate the quantity, in mg, of amprolium (C₁₄H₁₉ClN₄·HCl) in each mL of the Oral Solution taken by the formula:

(2000C/V)(r₁/r₂)

in which C is the concentration, in mg per mL, of USP Amprolium RS in the Standard preparation;

V is the volume, in mL, of Oral Solution taken to prepare the Assay preparation;

and r₁ and r₂ are the amprolium peak areas obtained from the Assay preparation and the Standard preparation, respectively.