Dexamethasone Tablets

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 Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of dexamethasone (C₂₂H₂₉FO₅).

2 IDENTIFICATION

2.1 A. Thin-Layer Chromatography

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

Sample solution: Nominally, 1 mg/mL of dexamethasone prepared as follows. Evaporate 10 mL of the Sample solution as directed under the Assay on a steam bath just to dryness, and dissolve the residue in 1 mL of chloroform.

Chromatographic system

• (See Chromatography 〈621〉, System Suitability.)
• Adsorbent: 0.25-mm layer of chromatographic silica gel mixture
• Application volume
• Sample solution: 10 µL
• Standard solution: 20 µL

Analysis

Samples: Standard solution and Sample solution

Develop the chromatogram in Solvent A as directed under Single-Steroid Assay 〈511〉. Mark the solvent front, and locate the spots on the plate by visualizing under short-wavelength UV light.

Acceptance criteria: The Rf value of the principal spot of the Sample solution corresponds to that of the Standard solution.

3 ASSAY

3.1 Procedure

Diluent: Methanol and water (50:50)

Mobile phase: Acetonitrile and water (33:66)

Standard solution: 0.1 mg/mL of USP Dexamethasone RS in Diluent

Sample solution: Nominally 0.1 mg/mL of dexamethasone prepared as follows. Transfer the equivalent of 5 mg of dexamethasone from finely powdered Tablets (NLT 10) to a 50-mL volumetric flask, and add 30 mL of Diluent. Sonicate the flask for 2 min, shake by mechanical means for 30 min, and dilute with Diluent to volume. Pass a portion of the mixture through a suitable filter to obtain a clear filtrate.

Chromatographic system

• (See Chromatography 〈621〉, System Suitability.)
• Mode: LC
• Detector: UV 254 nm
• Column: 4.6-mm × 30-cm; packing L1
• Injection volume: 5–25 µL

System suitability

• Sample: Standard solution
• Suitability requirements
• Relative standard deviation: NMT 3.0%, for five replicate injections

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of dexamethasone (C₂₂H₂₉FO₅) in the portion of Tablets 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 Dexamethasone RS in the Standard solution (mg/mL)

C_u = nominal concentration of dexamethasone in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

4.1 Dissolution 〈711〉

4.1.1 Test 1

Medium: Dilute 1 mL of hydrochloric acid with water to 100 mL; 500 mL

Apparatus 1: 100 rpm

Time: 45 min

Standard solution: Prepare as directed for Standard Preparation in Assay for Steroids 〈351〉, using USP Dexamethasone RS.

Sample solution: Extract a filtered aliquot of Medium, equivalent to 0.2 mg of dexamethasone, with three 15-mL portions of chloroform. Evaporate the combined chloroform extracts on a steam bath just to dryness, cool, and dissolve the residue in 20 mL of alcohol.

Analysis: Proceed as directed for Procedure in Assay for Steroids 〈351〉, except allow it to stand in the dark for 45 min.

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of dexamethasone (C₂₂H₂₉FO₅) dissolved:

Result = (A_u/A_s) × 20 × C_s × (V/V_s) × (1/L) × 100

A_u = absorbance of the Sample solution

A_s = absorbance of the Standard solution

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

V = volume of Medium, 500 mL

V_s = volume of Medium extracted with chloroform (mL)

L = label claim (mg/Tablet)

Tolerances: NLT 70% (Q) of the labeled amount of dexamethasone (C₂₂H₂₉FO₅) is dissolved.

4.1.2 Test 2 If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 2.

Medium: 0.1 N hydrochloric acid VS; 500 mL

Apparatus 1: 100 rpm

Time: 30 min

Solution A: 25% (v/v) phosphoric acid in water prepared as follows. Transfer 25 mL of phosphoric acid to a 100-mL volumetric flask containing about 50 ml of water. Cool and dilute with water to volume.

Buffer: 1.36 g/L of monobasic potassium phosphate in water. Add 1.0 mL of triethylamine to each liter of solution, and adjust with Solution A to a pH of 3.0.

Mobile phase: Methanol and Buffer (50:50)

Standard stock solution: 0.5 mg/mL of USP Dexamethasone RS in methanol. Sonicate to dissolve as needed.

Standard solution: (L/500) mg/mL of USP Dexamethasone RS from Standard stock solution in Medium, where L is the label claim in mg/Tablet

Sample solution: Pass a portion of the solution under test through a suitable filter of 0.45-µm pore size and discard the first 5 mL of the filtrate.

Chromatographic system

• (See Chromatography (621). System Suitability.)
• Mode: LC
• Detector: UV 240 nm
• Column: 4.6-mm x 5.0-cm; 3.5-µm packing 11
• Flow rate: 1 mL/min
• Injection volume: 50 µL
• Run time: NLT 1.3 times the retention time of dexamethasone

System suitability

• Sample: Standard solution
• Suitability requirements
• 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 dexamethasone (C₂₂H₂₉FO₅) dissolved:

Result =  (r_u/r_s) × C_s × V × (1/L) × 100

r_u = peak response of dexamethasone 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 (mg/mL)

V = volume of the Medium, 500 mL

L = label claim (mg/Tablet)

Tolerances: NLT 80% (Q) of the labeled amount of dexamethasone (C₂₂H₂₉FO₅) is dissolved.

4.1.3 Test 3: If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 3.

Medium: 0.1 N hydrochloric acid: 500 mL, deaerated

Apparatus 2: 75 rpm

Time: 30 min

Mobile phase: Acetonitrile and water (350:600)

Solution A: Methanol and water (50:50)

Standard stock solution A: 0.5 mg/mL of USP Dexamethasone RS in Solution A

Standard stock solution B: 0.05 mg/mL of USP Dexamethasone RS from Standard stock solution A in Medium

Standard solution: (L/500) mg/mL of USP Dexamethasone RS from Standard stock solution B in Medium, where L is the label claim in mg/Tablet

Sample solution: Pass a portion of the solution under test through a suitable filter of 0.45-µm pore size, discarding the first 1 mL of the filtrate.

Chromatographic system

• (See Chromatography (621), System Suitability.)
• Mode: LC
• Detector: UV 254 nm
• Column: 4.6-mm x 10-cm; 5-µm packing 11
• Flow rate: 1 mL/min
• Injection volume
• For Tablets labeled to contain 1, 1.5, 2, 4, and 6 mg of dexamethasone: 50 µL
• For Tablets labeled to contain 0.5 and 0.75 mg of dexamethasone: 100 µL
• Run time: NLT 1.5 times the retention time of dexamethasone

System suitability

• Sample: Standard solution
• Suitability requirements
• Tailing factor: 0.8-1.5
• Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of dexamethasone (C₂₂H₂₉FO₅) dissolved:

Result = (r_u/r_s) × C_s × V × (1/L) × 100

r_u = peak response of dexamethasone 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 (mg/mL) 

V = volume of the Medium, 500 mL

L = label claim (mg/Tablet)

Tolerances: NLT 80% (Q) of the labeled amount of dexamethasone (C₂₂H₂₉FO₅)) is dissolved.

4.2 UNIFORMITY OF DOSAGE UNITS (905)

4.2.1 Procedure for content uniformity

Standard solution: Prepare as directed for Standard Preparation in Assay for Steroids (351), using USP Dexamethasone RS.

Sample solution: Place 1 Tablet in a separator with 15 mL of water, and swirl to disintegrate the Tablet completely. Extract with four 10-mL portions of chloroform, filtering each portion through chloroform-washed cotton into a 50-mL volumetric flask, and add chloroform to volume. Pipet a volume of this solution, equivalent to 200 µg of dexamethasone, into a glass-stoppered, 50-mL conical flask. Evaporate the chloroform on a steam bath just to dryness, cool, and dissolve the residue in 20.0 mL of alcohol. Use this where Assay Preparation is specified in Assay for Steroids (351), Procedure.

Analysis

Samples: Standard solution and Sample solution

Proceed as directed in Assay for Steroids (351), Procedure, except allow it to stand in the dark for 45 min.

Calculate the percentage of total steroids, as dexamethasone (C₂₂H₂₉FO₅), in the Tablet:

Result = (A_u/A_s) x C_s x V x (1/L) x 100

A_u = absorbance of the Sample solution

A_s = absorbance of the Standard solution S

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

V = volume of the chloroform extract (mL) used to prepare the Sample solution

L = label claim (mg/Tablet)

Acceptance criteria: Meets the requirements

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in well-closed containers.

LABELING: When more than one Dissolution test is given, the labeling states the Dissolution test used only if Test 1 is not used.

USP REFERENCE STANDARDS (11)

USP Dexamethasone RS