Dexamethasone 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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1 DEFINITION

Dexamethasone Ophthalmic Suspension is a sterile, aqueous suspension of dexamethasone containing a suitable antimicrobial preservative. It may contain suitable buffers, stabilizers, and suspending and viscosity agents. It contains NLT 90.0% and NMT 110.0% of the labeled amount of dexamethasone (C₂₂H₂₉FO₅).

2 IDENTIFICATION

2.1 Delete the following:

THIN-LAYER CHROMATOGRAPHY

Adsorbent: 0.25-mm layer of chromatographic silica gel mixture.

Standard solution: 500 µg/mL of USP Dexamethasone RS in chloroform

Sample solution: Transfer a volume of Ophthalmic Suspension, equivalent to about 2.5 mg of dexamethasone, to a test tube, add 5 mL of chloroform, shake, and centrifuge.

Application volume: 10 µL of the chloroform layer

Developing solvent system: Single-Steroid Assay (511), Solvent A as directed under Single-Steroid Assay (511).

Analysis: Develop the chromatogram, mark the solvent front, and locate the spots on the plate by spraying with a 1 in 5 solution of p-toluenesulfonic acid in a mixture of 9 volumes of alcohol and 1 volume of propylene glycol, and heating until spots appear.

Acceptance criteria: The R, value of the principal spot of the Sample solution corresponds to that of the Standard solution. _{▲(USP 1-May-2019)}

2.2 Add the following:

A. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay _{▲(USP 1-May-2019)}

2.3 Add the following:

B. The UV spectrum of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay. _{▲(USP 1-May-2019)}

3 ASSAY

Change to read:

3.1 PROCEDURE

Solution A: 3.4 g/L of monobasic potassium phosphate in water. Adjust with phosphoric acid to a pH of 3.0.

Solution B: Acetonitrile

Mobile phase: See Table 1.

Table 1

Diluent: Acetonitrile and water (20:80)

System suitability solution: 0.06 mg/mL of USP Dexamethasone RS and 4 µg/mL of USP Betamethasone RS in Diluent. Sonicate to dissolve as needed.

Standard solution: 0.06 mg/mL of USP Dexamethasone RS in Diluent. Sonicate to dissolve as needed.

Sample solution: Prior to sampling, sonicate the drug product in the original container to achieve optimum homogeneity of the sample to be tested. Nominally 0.06 mg/mL of dexamethasone from Ophthalmic Suspension in Diluent. Vortex for 10-15 s and then sonicate for 2 min to dissolve.

3.1.1 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 240 nm. For Identification B, use a diode array detector in the range of 210-400 nm.

Column: 2.1-mm x 10-cm; 1.7-µm packing L1

Column temperature: 35°

Flow rate: 0.4 mL/min

Injection volume: 10 µL

3.1.2 System suitability

Samples: System suitability solution and Standard solution

[NOTE-See Table 2 for the relative retention times.]

3.1.3 Suitability requirements

Resolution: NLT 1.5 between betamethasone and dexamethasone, System suitability solution

Tailing factor: NMT 2.0, Standard solution

Relative standard deviation: NMT 1.0%, Standard solution

3.1.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of dexamethasone (C₂₂H₂₉FO₅) in the portion of Ophthalmic Suspension taken: 

                Result = (r_U/r_S) x (C_S/C_U) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution s

C_S = concentration of USP Dexamethasone RS in the Standard solution (mg/mL)

C_U = nominal concentration of dexamethasone in the Sample solution (mg/mL) _{▲(USP 1-May-2019)}

Acceptance criteria: 90.0%-110.0%

4 IMPURITIES

Add the following:

4.1 ORGANIC IMPURITIES

Solution A, Solution B, Mobile phase, Diluent, System suitability solution, and Chromatographic system: Proceed as directed in the Assay.

Standard solution: 0.6 µg/mL of USP Dexamethasone RS in Diluent. Sonicate to dissolve as needed.

Sample solution: Prior to sampling, sonicate the drug product in the original container to achieve optimum homogeneity of the sample to be tested. Nominally 300 µg/mL of dexamethasone from Ophthalmic Suspension in Diluent. Vortex for 10-15 s and then sonicate for 2 min to dissolve.

4.1.1 System suitability

[NOTE-See Table 2 for the relative retention times.]

Samples: System suitability solution and Standard solution

4.1.2 Suitability requirements

Resolution: NLT 1.5 between betamethasone and dexamethasone, System suitability solution

Relative standard deviation: NMT 5.0%, Standard solution

4.1.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of any individual degradation product in the portion of Ophthalmic Suspension taken:

                Result = (r_U/r_S) x (C_S/C_U) × 100

r_U = peak response of any individual degradation product from the Sample solution

r_S = peak response of dexamethasone from the Standard solution 

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

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

Acceptance criteria: See Table 2.

Table 2

^a 17,21-Dihydroxy-16a-methylpregna-1,4-diene-3,11,20-trione.

^b Process impurity included in the table for identification only. Process impurities are controlled in the drug substance and are not to be reported or included in the total degradation products for the drug product.

^c 17,21-Dihydroxy-16a-methylpregna-1,4,7,9 (11)-tetraene-3,20-dione.

5 SPECIFIC TESTS

PH (791): 5.0-6.0

STERILITY TESTS (71): Meets the requirements

6 ADDITIONAL REQUIREMENTS

Change to read:

PACKAGING AND STORAGE: Preserve in tight containers. ^▲Store upright at 8°-27° _{▲(USP 1-May-2019)}

Change to read:

USP REFERENCE STANDARDS (11)

USP Betamethasone RSA _{▲(USP 1-May-2019)}

USP Dexamethasone RS