Betamethasone Oral 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

Betamethasone Oral Solution contains NLT 90.0% and NMT 115.0% of the labeled amount of betamethasone (C₂₂H₂₉FO₅).

2 IDENTIFICATION

A. THIN-LAYER CHROMATOGRAPHIC IDENTIFICATION TEST (201)

Diluent: Chloroform and methanol (1:1)

Standard solution: 1 mg/mL of USP Betamethasone RS in alcohol

Sample solution: Place a volume of Oral Solution, equivalent to about 1 mg of betamethasone, in a centrifuge tube. Add 15 mL of 0.1 N hydrochloric acid and 20 mL of ethyl acetate. Shake the tube for about 1 min. Centrifuge to separate the phases. Transfer the upper phase (ethyl acetate) to a suitable container. Evaporate to dryness on a steam bath under a gentle stream of nitrogen. Allow to cool to room temperature. Dissolve the residue in about 0.5 mL of Diluent by using a vortex mixer. Transfer the solution to a 2-mL volumetric flask with small portions of Diluent. Dilute with Diluent to volume, and mix.

Evaporate 1 mL of the resulting solution on a steam bath just to dryness, and dissolve the residue in 0.5 mL of alcohol.

Chromatographic system

Application volume: 10 µL

Developing solvent system: Chloroform and diethylamine (2:1)

Spray reagent: Dilute sulfuric acid (1 in 2)

Analysis: Proceed as directed in the chapter. Locate the spots by lightly spraying with Spray reagent, and heat on a hot plate or under a lamp until spots appear.

Acceptance criteria: Meets the requirements

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

3 ASSAY

PROCEDURE

Protect all standard and sample solutions from light.

Buffer: 6.8 g/L of monobasic potassium phosphate in water. Adjust with phosphoric acid to a pH of 2.9.

Solution A: Acetonitrile and Buffer (25:75)

Solution B: Acetonitrile and Buffer (45:55)

Diluent: Dehydrated alcohol and water (2:3)

Mobile phase: See Table 1.

Table 1

Standard stock solution: 0.12 mg/mL of USP Betamethasone RS prepared as follows. Transfer a quantity of USP Betamethasone RS to a suitable container, and dilute, using sonication, with dehydrated alcohol to obtain a solution containing 0.3 mg/mL. Quantitatively dilute an aliquot of this solution with water to obtain a 0.12-mg/mL solution of betamethasone.

Standard solution: 0.048 mg/mL of USP Betamethasone RS in Diluent from Standard stock solution

Beclomethasone solution: 0.12 mg/mL of beclomethasone prepared as follows. Transfer a quantity of beclomethasone to a suitable container, and dilute, using sonication, with dehydrated alcohol to obtain a solution containing 0.3 mg/mL. Quantitatively dilute an aliquot of this solution with water to obtain a 0.12 mg/mL solution of beclomethasone.

System suitability solution: 0.048 mg/mL each of USP Betamethasone RS and beclomethasone in Diluent, prepared from the Standard stock solution and Beclomethasone solution

Sample solution: Nominally 0.048 mg/mL of betamethasone prepared as follows. Transfer a measured volume of Oral Solution, containing a known amount of betamethasone, to a suitable volumetric flask, and dilute with Diluent to volume.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4.6-mm x 15-cm; 4-um packing L1

Flow rate:

1.5 mL/min

Injection volume: 50 µL

System suitability

Samples: Standard solution and System suitability solution

[NOTE-The relative retention times for betamethasone and beclomethasone are 1.0 and 1.2, respectively.]

Suitability requirements

Resolution: NLT 4.0 between betamethasone and beclomethasone, System suitability solution

Tailing factor: NMT 1.5 for betamethasone, 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 betamethasone (C₂₂H₂₉FO₅) in the portion of Oral Solution 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 Betamethasone RS in the Standard solution (mg/mL)

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

Acceptance criteria: 90.0%–115.0%

4 IMPURITIES

ORGANIC IMPURITIES

Protect all sample and standard solutions from light.

Buffer, Solution A, Solution B, Diluent, Mobile phase, Standard stock solution, System suitability solution, Sample solution, and

Chromatographic system: Proceed as directed in the Assay.

Standard solution: 0.48 µg/mL of USP Betamethasone RS in Diluent from the Standard stock solution

Sensitivity solution: 0.024 µg/mL of USP Betamethasone RS in Diluent from the Standard solution

System suitability

Samples: System suitability solution and Sensitivity solution

[NOTE-The relative retention times for betamethasone and beclomethasone are 1.0 and 1.2, respectively.]

Suitability requirements

Resolution: NLT 4.0 between betamethasone and beclomethasone, System suitability solution

Relative standard deviation: NMT 10% for betamethasone, Sensitivity solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each related compound in the portion of Oral Solution taken:

Result = (r_u /r_s ) × (C_s /C_u ) × 100

r_u = peak response for individual related compounds from the Sample solution

r_s = peak response for betamethasone from the Standard solution

C_s = concentration of USP Betamethasone RS in the Standard solution (µg/mL)

C_u = nominal concentration of betamethasone in the Sample solution (µg/mL)

Acceptance criteria: See Table 2.

Table 2

5 SPECIFIC TESTS

MICROBIAL ENUMERATION TESTS (61) and TESTS FOR SPECIFIED MICROORGANISMS (62): It meets the requirements of the test for the absence of Escherichia

coli. The total aerobic microbial count is NMT 102 cfu/ml, and the total combined molds and yeasts count is NMT 10¹ cfu/mL.

PH (791): 2.8-3.6

DELIVERABLE VOLUME (698): Meets the requirements for oral solution packaged in multiple-unit containers

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Store at controlled room temperature, protected from light. Preserve in tight containers.

USP REFERENCE STANDARDS (11)

USP Betamethasone RS