Sodium Chloride Ophthalmic Ointment

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

Sodium Chloride Ophthalmic Ointment is Sodium Chloride in a suitable ophthalmic ointment base. It contains NLT 90.0% and NMT 110.0% of the labeled amount of sodium chloride (NaCl). It is sterile.

2 IDENTIFICATION

A. Identification Tests—General 〈191〉, Chemical Identification Tests, Sodium

Sample solution: Transfer a quantity of Ophthalmic Ointment, equivalent to about 200 mg of sodium chloride, to a separator containing 25 mL of ether, and extract with 5 mL of water. Use the aqueous extract.

Acceptance criteria: Meets the requirements

Delete the following:

B. Identification Tests—General 〈191〉, Chemical Identification Tests, Chloride

Sample solution: Use the Sample solution from Identification A.

Acceptance criteria: Meets the requirements (USP 1-Aug-2022)

Add the following:

B. The retention time of the chloride peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

(USP 1-Aug-2022)

3 ASSAY

Change to read:

Procedure

Use water with a resistivity of NLT 18 megohm-cm to prepare the solutions.

Solution A: 100 mM potassium hydroxide

Solution B: Water

Mobile phase: See Table 1. [Note—Alternatively, Mobile phase can be generated electrolytically by using an automatic eluant generator.]

Table 1

System suitability solution: 100 μg/mL of USP Sodium Chloride RS and 8 μg/mL of USP Sodium Nitrite RS in water

Standard solution: 100 μg/mL of USP Sodium Chloride RS in water

Sample stock solution: Nominally 625 μg/mL of sodium chloride prepared as follows. Transfer an appropriate portion of Ophthalmic

Ointment to a suitable flask. Add 20 mL each of water and methylene chloride, and shake well until Ophthalmic Ointment is dispersed.

Allow the layers to separate and use the aqueous layer.

Sample solution: Nominally 100 μg/mL of sodium chloride in water, from the Sample stock solution

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: Conductivity with suppression

Columns

Guard: 4.0-mm × 5-cm; 11-μm packing L121. [Note—Alternatively, a 4.0-mm × 0.5-cm; 5.0-μm packing L91 column may be used.]

Analytical: 4.0-mm × 25-cm; 7.5-μm packing L103. [Note—Alternatively, a 4.0-mm × 15-cm; 5.0-μm packing L91 column may be used.]

Column temperature: 35°

Flow rate: 1.2 mL/min

Injection volume: 10 μL

System suitability

Samples: System suitability solution and Standard solution

[Note—The relative retention times for the chloride and nitrite peaks are 1.0 and 1.1, respectively.]

Suitability requirements

Resolution: NLT 2.0 between the chloride and nitrite peaks, System suitability solution

Tailing factor: NMT 2.0 for the chloride and nitrite peaks, System suitability solution

Relative standard deviation: NMT 2.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of sodium chloride (NaCl) in the portion of Ophthalmic Ointment taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of chloride from the Sample solution

r_S = peak response of chloride from the Standard solution

C_S = concentration of USP Sodium Chloride RS in the Standard solution (μg/mL)

C_U = nominal concentration of sodium chloride in the Sample solution (μg/mL) (USP 1-Aug-2022)

Acceptance criteria: 90.0%–110.0%

4 SPECIFIC TESTS

Sterility Tests 〈71〉: Meets the requirements

Other Requirements: It meets the requirements in Ophthalmic Products—Quality Tests 〈771〉, Drug Product Quality, Universal Tests, Particulate and

Foreign Matter and Container Contents.

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in collapsible ophthalmic ointment tubes. Store at controlled room temperature. Store away from heat. Protect

from freezing.

Add the following:

USP Reference Standards 〈11〉

USP Sodium Chloride RS

USP Sodium Nitrite RS (USP 1-Aug-2022)