Neomycin Sulfate and Dexamethasone Sodium Phosphate 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

Neomycin Sulfate and Dexamethasone Sodium Phosphate Ophthalmic Solution is a sterile, aqueous solution of Neomycin Sulfate and Dexamethasone Sodium Phosphate. It contains the equivalent of NLT 90.0% and NMT 130.0% of the labeled amount of neomycin, and the equivalent of NLT 90.0% and NMT 115.0% of the labeled amount of dexamethasone phosphate (C₂₂H₃₀FO₈P). It may contain one or more suitable buffers, dispersants, and preservatives.

[Note-Where Neomycin Sulfate and Dexamethasone Sodium Phosphate Ophthalmic Solution is prescribed, without reference to the amount of neomycin or dexamethasone phosphate contained therein, a product containing 3.5 mg/mL of neomycin and 1.0 mg/mL of dexamethasone phosphate shall be dispensed.]

2 IDENTIFICATION

A. Thin-Layer Chromatographic Identification Test 〈201BNP〉: Meets the requirements for neomycin

B. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay for Dexamethasone Phosphate.

3 ASSAY

3.1 Neomycin

(See Antibiotics-Microbial Assays 〈81〉.)

Analysis: Dilute an aliquot of Ophthalmic Solution with Buffer B.3 to obtain a Test Dilution with a neomycin concentration that is nominally equivalent to the median level of the standard (1.0 µg/mL).

Acceptance criteria: 90.0%–130.0%

3.2 Dexamethasone Phosphate

Solution A: 0.29 g/L of dibasic sodium phosphate

Solution B: 13.80 g/L of monobasic sodium phosphate

Mobile phase: Acetonitrile and Solution B (31:69)

Standard solution: 27 µg/mL of USP Dexamethasone Sodium Phosphate RS in Solution A. Pass through a filter of 1-µm or finer pore size.

Sample solution: Nominally 25 µg/mL of dexamethasone phosphate from Ophthalmic Solution in Solution A prepared as follows. Slowly dilute a portion of Ophthalmic Solution with Solution A to volume, mix, and pass through a suitable filter of 1-µm or finer pore size.

Chromatographic system

• (See Chromatography 〈621〉, System Suitability.)
• Mode: LC
• Detector: UV 254 nm
• Column: 3.9-mm × 30-cm; 10-µm packing L1
• Flow rate: 1.3 mL/min
• Injection volume: 50 µL

System suitability

• Sample: Standard solution
• [Note-The retention time for dexamethasone phosphate is about 8.5 min.]
• Suitability requirements
• Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of dexamethasone phosphate (C₂₂H₃₀FO₈P) in each mL of Ophthalmic Solution taken:

Result =(rᵤ/rₛ) × (Cₛ/Cᵤ) × (Mr₁/Mr₂) × 100

rᵤ = peak area from the Sample solution

rₛ = peak area from the Standard solution

Cₛ = concentration of USP Dexamethasone Sodium Phosphate RS in the Standard solution (µg/mL)

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

Mr₁ = molecular weight of dexamethasone phosphate, 472.44

Mr₂ = molecular weight of dexamethasone sodium phosphate, 516.40

Acceptance criteria: 90.0%–115.0%

4 SPECIFIC TESTS

Sterility Tests 〈71〉: Meets the requirements

pH 〈791〉: 6.0–8.0

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers, and avoid exposure to excessive heat.

USP Reference Standards 〈11〉

USP Dexamethasone Sodium Phosphate RS

USP Neomycin Sulfate RS