Eprinomectin

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

Eprinomectin is a mixture of component B_1a (C₅₀H₇₅NO₁₄) and component B_1b (C₄₉H₇₃NO₁₄). It contains NLT 90.0% of component B_1a(C₅₀H₇₅NO₁₄) and NLT 95.0% of components B_1a(C₅₀H₇₅NO₁₄) and B_b (C₄₉H₇₃NO₁₄), calculated on the anhydrous, solvent-free, and antioxidant-free basis. It may contain small amounts of a suitable antioxidant.

2 IDENTIFICATION

Change to read:

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

B. The retention times of the component B peak and the component B peak of the Sample solution correspond to those of the Standard solution, as obtained in the Assay.

3 ASSAY

Procedure

Solution A: 0.1% (v/v) solution of perchloric acid in water

Solution B: Acetonitrile

Mobile phase: See Table 1.

Table 1

Diluent: Methanol and water (4:1)

Standard solution: 0.500 mg/mL of USP Eprinomectin RS in Diluent

System suitability solution: Transfer 4 mL of Standard solution to an LC vial. Add 2 drops of 1 M sodium hydroxide and let stand for 20 min prior to injection.

Sample solution: 0.500 mg/mL of Eprinomectin in Diluent

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 245 nm

Column: 4.6-mm × 25-cm; 5-μm packing L7

Column temperature: 40°

Flow rate: 1.5 mL/min

Injection volume: 15 μL

System suitability

Samples: Standard solution and System suitability solution

[Note—For relative retention times, see Table 2.]

Table 2

Suitability requirements

Resolution: NLT 3 between component B_1b and component B_1a; NLT 1 between component B_1a and impurities C + D, System suitability solution

Column efficiency: NLT 4,500 theoretical plates for component B_1a, System suitability solution

Symmetry factor: NMT 1.5 for component B_1a, System suitability solution

Relative standard deviation: NMT 1.0% from five injections for component B_1a, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of component B_1a (C₅₀H₇₅NO₁₄) in the portion of Eprinomectin taken:

Result = [r_1a /(r_1a + r_1b )] × 100

r_1a = peak area of component B_1a from the Sample solution

r_1b = peak area of component B_1b from the Sample solution

Calculate the percentage of component B_1a (C₅₀H₇₅NO₁₄) and component B_1b (C₄₉H₇₃NO₁₄) in the portion of Eprinomectin taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak area of component B or component B from the Sample solution

r_S= peak area of component B or component B from the Standard solution

C_S = concentration of component B or component B in the Standard solution (mg/mL)

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

Acceptance criteria: NLT 90.0% of component B_1a and NLT 95.0% of components B_1a and B_1b, on the anhydrous, solvent-free, and antioxidant-free basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.1%

Limit of 8a-oxo-B

Solution A, Solution B, Diluent, Standard solution, System suitability solution, and Sample solution: Prepare as directed in the Assay.

Mobile phase: Acetonitrile and Solution A (13:7)

Butylated hydroxytoluene stock solution: 0.5 mg/mL of butylated hydroxytoluene in methanol. Sonicate to dissolve, if necessary.

Butylated hydroxytoluene solution: 0.01 mg/mL of butylated hydroxytoluene from Butylated hydroxytoluene stock solution in Diluent

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 280 nm

Column: 4.6-mm × 25-cm; 5-μm packing L7

Column temperature: 40°

Flow rate: 1.5 mL/min

Injection volume: 15 μL

System suitability 1

Samples: Standard solution and System suitability solution

System suitability determination: Use the conditions as directed for Chromatographic system and the suitability requirements for System

suitability as directed in the Assay.

System suitability 2

Samples: Sample solution and Butylated hydroxytoluene solution

Suitability requirements

Relative standard deviation: NMT 3.0% from six injections, Butylated hydroxytoluene solution

Analysis

Samples: Sample solution and Butylated hydroxytoluene solution

[Note—The retention time for 8a-oxo-B is 4–9 min from the Sample solution, and the retention time for butylated hydroxytoluene is 12–17 min from Butylated hydroxytoluene solution.]

Calculate the percentage of 8a-oxo-B , on the anhydrous, solvent-free, and antioxidant-free basis in the portion of Eprinomectin taken:

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

r_U = peak area of 8a-oxo-B from the Sample solution

r_S = peak area of butylated hydroxytoluene from the Butylated hydroxytoluene solution

C_S = concentration of butylated hydroxytoluene in the Butylated hydroxytoluene solution (mg/mL)

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

F = relative response factor for butylated hydroxytoluene with respect to 8a-oxo-B , 0.4

P = purity of butylated hydroxytoluene used to prepare the Butylated hydroxytoluene solution

Acceptance criteria: NMT 0.5%

Change to read:

Organic Impurities

Solution A, Solution B, Mobile phase, Diluent, Standard solution, System suitability 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 Eprinomectin taken:

Result = (r_U/r_T) × 100

r_U = peak area of each individual related substance from the Sample solution

r_T = sum of the responses of all the peaks

Acceptance criteria: [Note—See Table 2 for the relative retention times of impurity A and impurity E.]

Impurities with relative retention times of 0.23, 0.93, and 1.16 with respect to the B peak: NMT 1.0%

Impurity A: NMT 1.0%

Impurity E: NMT 1.0%

All other known impurities: NMT 0.5%

Total unknown impurities: NMT 1.0% (ERR 1-Jun-2019)

Total impurities: NMT 5.0%

5 SPECIFIC TESTS

Optical Rotation 〈781S〉, Procedures, Specific Rotation

Sample solution: 5 mg/mL of Eprinomectin in chloroform

Acceptance criteria: +132° to +140°, determined at 405 nm on the anhydrous, solvent-free, and antioxidant-free basis

Water Determination 〈921〉, Method I, Method Ia

Sample: 0.250 g

Acceptance criteria: NMT 2.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers, and store between 2° and 8° at ambient humidity.

Labeling: Label it to state the name(s) and amount(s) of any added substance(s). Label to indicate that it is for veterinary use only.

USP Reference Standards 〈11〉

USP Eprinomectin RS