Prednisolone Sodium Phosphate

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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C₂₁H₂₇Na₂O₈P  484.39

Pregna-1,4-diene-3,20-dione, 11,17-dihydroxy-21-(phosphonooxy)-, disodium salt, (11β)-;

11β,17,21-Trihydroxypregna-1,4-diene-3,20-dione 21-(disodium phosphate)  CAS RN^®: 125-02-0; UNII: IV021NXA9J.

1 DEFINITION

Prednisolone Sodium Phosphate contains NLT 96.0% and NMT 102.0% of prednisolone sodium phosphate (C₂₁H₂₇Na₂O₈P), calculated on the anhydrous basis.

2 IDENTIFICATION

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K

B. Identification Tests—General 〈191〉, Chemical Identification Tests, Sodium and Identification Tests—General 〈191〉, Chemical Identification Tests, Phosphate

Sample: The residue from the ignition of 20 mg of Prednisolone Sodium Phosphate

Acceptance criteria: Meets the requirements

3 ASSAY

Change to read:

3.1 Procedure

Buffer solution: Transfer 6.6 g of hexylamine and 5.32 g of monobasic ammonium phosphate into an appropriate flask. After 10 min, add 1850 g of water and dissolve the contents while stirring. Adjust with phosphoric acid to a pH of 6.40 ± 0.05.

Mobile phase: To the entire quantity of Buffer solution prepared above add 390 g of acetonitrile, mix by stirring, and then sonicate for NMT 2 min.

System suitability solution: 0.01 mg/mL each of USP Prednisolone RS and USP Prednisolone Sodium Phosphate RS in Mobile phase

Standard solution: 0.3 mg/mL of USP Prednisolone RS in Mobile phase

Sample solution: 0.42 mg/mL of Prednisolone Sodium Phosphate in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4.6-mm × 7.5-cm; 3.5-µm packing L1

Temperatures:

Autosampler: 6°

Column: 35°

Flow rate: 1.5 mL/min

Injection volume: 20 µL

Run time: NLT 1.6 times the retention time of prednisolone sodium phosphate

System suitability

Samples: System suitability solution and Standard solution

[Note—The relative retention times for prednisolone and prednisolone sodium phosphate are about 0.52 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 12 between prednisolone and prednisolone sodium phosphate, System suitability solution

Relative standard deviation: NMT 1.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of prednisolone sodium phosphate (C₂₁H₂₇Na₂O₈P) in the portion of Prednisolone Sodium Phosphate taken:

Result = (r_U/r_S) × (C_S/C_U) × (M_r1/M_r2) × 100

r_U = peak response of prednisolone sodium phosphate from the Sample solution

r_S = peak response of prednisolone from the Standard solution

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

C_U = concentration of Prednisolone Sodium Phosphate in the Sample solution (mg/mL)

M_r1 = molecular weight of prednisolone sodium phosphate, 484.39

M_r2 = molecular weight of prednisolone, 360.45

Acceptance criteria: 96.0%–102.0% on the anhydrous basis 

4 IMPURITIES

Delete the following:

4.1 Selenium 〈291〉

Sample: 200 mg of Prednisolone Sodium Phosphate

Acceptance criteria: 0.003%

Change to read:

4.2 Phosphate Ions

Solution A: 50 mg/mL of ammonium molybdate in 1 N sulfuric acid

Solution B: 3.5 mg/mL of p-methylaminophenol sulfate and 200 mg/mL of sodium bisulfite in water prepared as follows. Dissolve 350 mg of p-methylaminophenol sulfate in 50 mL of water, add 20 g of sodium bisulfite, mix and dissolve, then dilute with water to 100 mL.

Sample solution: Dissolve 50 mg of Prednisolone Sodium Phosphate in a mixture of 10 mL of water and 5 mL of 2 N sulfuric acid TS contained in a 25-mL volumetric flask, by warming, if necessary. Add 1 mL each of Solution A and Solution B, dilute with water to volume, and allow to stand at room temperature for 30 min.

Standard stock solution: 0.10 mg/mL of phosphate (PO₄³⁻) prepared as follows. Dissolve 143.3 mg of dried monobasic potassium phosphate (KH₂PO₄) in water to make 1000.0 mL.

Standard solution: Concomitantly prepare as directed for the Sample solution, using 5.0 mL of Standard stock solution instead of the 50 mg of Prednisolone Sodium Phosphate.

Instrumental conditions

Mode: Vis

Analytical wavelength: 730 nm

Cell: 1 cm

Blank: Water

Analysis:

Concomitantly determine the absorbances of the Sample solution and the Standard solution.

Acceptance criteria: The absorbance of the Sample solution is NMT that of the Standard solution; NMT 1.0%

Change to read:

4.3 Organic Impurities

Buffer solution, Mobile phase, and System suitability solution:

Prepare as directed in the Assay.

Standard solution: 0.001 mg/mL of USP Prednisolone Sodium Phosphate RS in Mobile phase

Sample solution: 1 mg/mL of Prednisolone Sodium Phosphate in Mobile phase

Chromatographic system: Proceed as directed in the Assay, except for the Run time.

Run time: NLT 4 times the retention time of prednisolone sodium phosphate

System suitability

Samples: System suitability solution and Standard solution

[Note—See Table 1 for the relative retention times.]

Suitability requirements

Resolution: NLT 12 between prednisolone and prednisolone sodium phosphate, System suitability solution

Relative standard deviation: NMT 5.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each individual impurity in the portion of Prednisolone Sodium Phosphate taken:

Result = (r_U/r_S) × (C_S/C_U) × (1 / F) × 100

r_U = peak response of each individual impurity from the Sample solution

r_S = peak response of prednisolone sodium phosphate from the Standard solution

C_S = concentration of USP Prednisolone Sodium Phosphate RS in the Standard solution (mg/mL)

C_U = concentration of Prednisolone Sodium Phosphate in the Sample solution (mg/mL)

F = relative response factor (see Table 1)

Acceptance criteria: See Table 1.

Table 1

ᵃ 11β,17,20-Trihydroxy-21-nor-13(17)a-homopregnane-1,4-diene-3,13a-dione 20-phosphate.

ᵇ 11β,17α-Dihydroxyandrosta-1,4-diene-3-one 17β-carboxylic acid.

ᶜ 11β,17β,20-Trihydroxy-21-nor-14(15)a-homopregnane-1,4-diene-3,16-dione 20-phosphate.

ᵈ 11β,17,21-Trihydroxypregna-1,4-diene-3,20-dione.

ᵉ 11β,17α,20-Trihydroxy-21-nor-14(15)a-homopregnane-1,4-diene-3,16-dione 20-phosphate.

ᶠ 21-Oxo-11β,17,21-trihydroxypregna-1,4-diene-3,20-dione.

ᵍ 11β-Hydroxyandrosta-1,4-diene-3,17-dione.

ʰ 16β-Phosphoryloxyacetyl-11β,16α-dihydroxyandrosta-1,4-diene-3-one 11-phosphate.

ⁱ 21-Oxo-20-phosphoryloxy-11β-hydroxypregna-1,4,17-triene-3-one.

5 SPECIFIC TESTS

5.1 Optical Rotation 〈781S〉, Procedures, Specific Rotation

Sample solution: 10 mg/mL of Prednisolone Sodium Phosphate in a mixture of pH 7.0 phosphate buffer and carbon dioxide-free water (90:10)

Acceptance criteria: +95° to +102°

5.2 pH 〈791〉

Sample solution: 10 mg/mL of Prednisolone Sodium Phosphate in water

Acceptance criteria: 7.5–10.5

5.3 Water Determination 〈921〉, Method I: NMT 6.5%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

USP Reference Standards 〈11〉

USP Prednisolone RS

USP Prednisolone Sodium Phosphate RS