Idoxuridine Ophthalmic 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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1 DEFINITION

Idoxuridine Ophthalmic Solution is a sterile, aqueous solution of Idoxuridine. It contains NLT 0.09% and NMT 0.11% of idoxuridine (C₉H₁₁IN₂O₅).

It may contain suitable buffers, stabilizers, and antimicrobial agents.

2 IDENTIFICATION

A.

Standard solution and Sample solution: Use as directed in the Assay.

Acceptance criteria: The UV absorption spectrum of the Sample solution exhibits maxima and minima at the same wavelengths as those of the Standard solution.

3 ASSAY

Procedure

Chromatographic column:

Mix 4 g of chromatographic siliceous earth with 4 mL of 0.1 N hydrochloric acid in a glass mortar until the mixture is fluffy. Transfer to a 19- × 250-mm chromatographic tube (see Chromatography 〈621〉) that contains a pledget of glass wool and is fitted with a stopcock at the bottom. Tamp gently to compress to a uniform mass.

Eluting solvent:

Butyl alcohol and chloroform (1:5)

Standard stock solution:

0.5 mg/mL of USP Idoxuridine RS in methanol

Standard solution:

Dilute 5.0 mL of Standard stock solution with Eluting solvent to 100.0 mL.

Sample solution:

Nominally 25 µg/mL of idoxuridine in eluant obtained from the Chromatographic column. Mix an equivalent to 5 mg of idoxuridine from Ophthalmic Solution with 3 g of chromatographic siliceous earth in a glass mortar until the mixture is fluffy.

Instrumental conditions

Mode: UV

Analytical wavelengths: 320 and 283 nm

Cell: 1 cm

Blank: Eluting solvent

Analysis

Samples: Standard solution and Sample solution

Transfer the Sample solution to the prepared Chromatographic column. Transfer 2 g of chromatographic siliceous earth and 2 mL of 0.1 N hydrochloric acid to the glass mortar, and mix until fluffy. Use this material to rinse the mortar and pick up any remaining Ophthalmic Solution. Transfer half of this mixture to the tube, and tamp gently until the column appears uniform. Transfer the remaining portion to the Chromatographic column, and tamp as before. Wipe the walls of the mortar with a small pledget of glass wool, and insert the pledget in the top of the column. Elute with 200 mL of Eluting solvent at a flow rate of approximately 1 mL/min, discarding the first 20 mL of the eluate. Collect the remainder of the eluate in a 200-mL volumetric flask, and dilute with Eluting solvent to volume. Determine the absorbances of this solution and the Standard solution.

Calculate the percentage of idoxuridine (C₉H₁₁IN₂O₅) in the portion of Ophthalmic Solution taken:

Result = (Aᵤ / Aₛ) × (Cₛ / Cᵤ) × 100

Aᵤ = difference in the absorbances of the Sample solution at the wavelengths indicated by (A₂₈₃ − A₃₂₀)

Aₛ = difference in the absorbances of the Standard solution at the wavelengths indicated by (A₂₈₃ − A₃₂₀)

Cₛ = concentration of USP Idoxuridine RS in the Standard solution (µg/mL)

Cᵤ = nominal concentration of idoxuridine in the Sample solution (µg/mL)

Acceptance criteria: 0.09%–0.11%

4 SPECIFIC TESTS

Sterility Tests 〈71〉: Meets the requirements

pH 〈791〉: 4.5–7.0

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers in a cold place.

USP Reference Standards 〈11〉

USP Idoxuridine RS