Rimexolone Ophthalmic Suspension

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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Rimexolone Ophthalmic Suspension

1 DEFINITION

Rimexolone Ophthalmic Suspension is a sterile suspension of Rimexolone in a suitable aqueous medium. It contains NLT 90.0% and NMT 110.0% of the labeled amount of rimexolone (C₂₄H₃₄O₃). It may contain suitable stabilizers, buffers, and antimicrobial agents.

2 IDENTIFICATION

A. 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

3.1 Procedure

Mobile phase: Acetonitrile and water (60:40)

Standard stock solution: 1 mg/mL of USP Rimexolone RS in methanol

Standard solution: 0.2 mg/mL of USP Rimexolone RS in Mobile phase from Standard stock solution

Sample stock solution: Nominally 1 mg/mL of rimexolone, prepared as follows. Transfer an amount nominally equivalent to 25 mg of rimexolone from a portion of Ophthalmic Suspension to a 25-mL volumetric flask. Dilute with methanol to volume and sonicate for 2 min.

Sample solution: Nominally 0.2 mg/mL of rimexolone from the Sample stock solution in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 242 nm

Column: 4.6-mm × 25-cm; 5-µm packing L1

Flow rate: 1 mL/min

Injection volume: 20 µL

System suitability

Sample: Standard solution

Suitability requirements

Capacity factor, k′: NLT 1.5

Column efficiency: NLT 3000 theoretical plates

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of rimexolone (C₂₄H₃₄O₃) in the portion of Ophthalmic Suspension 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 Rimexolone RS in the Standard solution (mg/mL)

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

Acceptance criteria: 90.0%–110.0%

4 SPECIFIC TESTS

Sterility Tests 〈71〉: Meets the requirements

pH 〈791〉: 6.0–8.0

Viscosity—Rotational Methods 〈912〉

Analysis: Equip a cone-and-plate rheometer¹ following Method III. The shear rate under the test condition is 11.5 s^-1 and temperature is 25°.

Acceptance criteria: 15–200 mPa·s

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

USP Reference Standards 〈11〉

USP Rimexolone RS (USP 1-Dec-2024)

¹ Brookfield cone-and-plate rheometer, with spindle CP-42 (#42), is operated at 3 rpm. Any other equivalent rheometer is suitable as well.