Ezetimibe

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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C₂₄H₂₁F₂NO₃ 409.43

2-Azetidinone, 1-(4-fluorophenyl)-3-[3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4-hydroxyphenyl)-, [3R-[3α(S*),4β]]-;(3R,4S)-1-(p-Fluorophenyl)-3-[(3S)-3-(pfluorophenyl)-3-hydroxypropyl]-4-(p-hydroxyphenyl)-2-azetidinone; (3R,4S)-1-(4-Fluorophenyl)-3-[(S)-3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4-hydroxyphenyl)-azetidin-2-one CAS RN®: 163222-33-1; UNII:EOR26LQQ24.

1 DEFINITION

Ezetimibe contains NLT 98.0% and NMT 102.0% of ezetimibe (C₂₄H₂₁F₂NO₃), calculated on the anhydrous and solvent-free basis.

2 IDENTIFICATION

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

B. The ratio of the retention time of the ezetimibe peak of the Sample solution to that of the System suitability solution obtained in Organic

Impurities, Procedure 2 is between 0.97 and 1.03.

3 ASSAY

Change to read:

3.1 Procedure

Solution A: Water

Solution B: Acetonitrile

Solution C: Methanol

Mobile phase: See Table 1. Adjust the percentages of Solution A and Solution B to achieve a retention time of about 33 min for the ezetimibe peak. The percentage of Solution C should remain unchanged.

[Note-Ezetimibe and related impurities are sensitive to small variations in Mobile phase composition, which may affect resolution and retention characteristics.] (USP 1-Aug-2024)

Table 1

Diluent: Acetonitrile, methanol, and water (27:10:63). (USP 1-Aug-2024) Add 1.0 mL of glacial acetic acid per each liter of the mixture.

Standard solution: 0.25 mg/mL of USP Ezetimibe RS prepared as follows. Transfer a suitable amount of USP Ezetimibe RS to a suitable volumetric flask. Dissolve in about 1%–2% of the flask volume of acetonitrile, and dilute with Diluent to volume. [Note—The Standard solution contains a detectable level of o-fluorobenzene isomer (approximately 0.04%) from USP Ezetimibe RS.]

Sample solution: 0.25 mg/mL of Ezetimibe prepared as follows. Transfer a suitable amount of Ezetimibe to a suitable volumetric flask.

Dissolve in about 1%–2% of the flask volume of acetonitrile, and dilute with Diluent to volume.

3.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detectors

0–5 min: UV 215 nm

5–100 min: UV 248 nm

Column: 4.6-mm × 15-cm; 5-μm packing L43

Flow rate: 2 mL/min

Injection volume: 60 μL

3.3 System suitability

Sample: Standard solution

3.4 Suitability requirements

Tailing factor: NMT 1.5 for ezetimibe

Relative standard deviation: NMT 0.73% for ezetimibe

3.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of ezetimibe (C₂₄H₂₁F₂NO₃) in the portion of Ezetimibe taken:

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

r_U = peak response of ezetimibe from the Sample solution

r_S = peak response of ezetimibe from the Standard solution

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

C_U = concentration of Ezetimibe in the Sample solution (mg/mL)

Acceptance criteria: 98.0%–102.0% on the anhydrous and solvent-free basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.2%

Change to read:

Organic Impurities, Procedure 1

Solution A, Solution B, Solution C, (USP 1-Aug-2024) Mobile phase, Diluent, Standard solution, Sample solution, and Chromatographic system: Proceed as directed in the Assay.

Sensitivity solution: 0.125 μg/mL of USP Ezetimibe RS from the Standard solution in Diluent

System suitability

Samples: Standard solution and Sensitivity solution

[Note-The relative retention times in Table 2 are provided as information that could aid in peak assignment.]

Table 2 (USP 1-Aug-2024)

^a(3R,4S)-3-[(S)-3-(4-Fluorophenyl)-3-hydroxypropyl]-4-(4-hydroxyphenyl)-1-phenylazetidin-2-one.

^b The two ezetimibe diastereomers, R,R,R- and S,S,S-, elute as one peak (USP 1-Aug-2024) .

^c(3R,4S)-1-(3-Fluorophenyl)-3-[(S)-3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4-hydroxyphenyl)azetidin-2-one.

^d(3R,4S)-1-(4-Fluorophenyl)-3-[3-(4-fluorophenyl)-3-oxopropyl]-4-(4-hydroxyphenyl)azetidin-2-one.

Suitability requirements

Resolution: NLT 1.5 between ezetimibe and o-fluorobenzene isomer, Standard solution

Tailing factor: NMT 1.5 for ezetimibe, Standard solution

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

Analysis

Sample: Sample solution

Calculate the percentage of any impurity (USP 1-Aug-2024) in the portion of Ezetimibe taken:

Result = (r_U /r_T ) × (1/F) × 100

r_U = peak response of each impurity from the Sample solution

r_T = sum of all peak responses from the Sample solution

F = relative response factor from Table 3

Acceptance criteria: See Table 3. The reporting threshold is 0.05%.

Table 3

^a Excludes ezetimibe diastereomers, which are quantitated using Organic Impurities, Procedure 2.(USP 1-Aug-2024)

Change to read:

Organic Impurities, Procedure 2

Mobile phase: Acetonitrile and water (45:55)

Diluent: Acetonitrile with 0.1% glacial acetic acid (v/v)

System suitability solution: 0.4 mg/mL of USP Ezetimibe System Suitability Mixture RS in Diluent

Sensitivity solution: 0.2 μg/mL of USP Ezetimibe RS in Diluent

Sample solution: 0.4 mg/mL of Ezetimibe in Diluent

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 248 nm

Column: Two columns in series of 4.6-mm × 15-cm; 5-μm packing L93

Column temperature: 5°

Flow rate: 0.35 mL/min

Injection volume: 10 μL

Run time: NLT 1.4 times the retention time of the ezetimibe peak

System suitability

Samples: System suitability solution and Sensitivity solution

[Note-The relative retention times in Table 4 are provided as information that could aid in peak assignment.]

Table 4 (USP 1-Aug-2024)

^a(3S,4S)-1-(4-Fluorophenyl)-3-[(S)-3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4-hydroxyphenyl)azetidin-2-one.

^b(3R,4R)-1-(4-Fluorophenyl)-3-[(R)-3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4-hydroxyphenyl)azetidin-2-one.

^cDes-fluoroaniline analog impurity is quantitated using Procedure 1.

^d(3S,4R)-1-(4-Fluorophenyl)-3-[(S)-3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4-hydroxyphenyl)azetidin-2-one.

^e(3S,4R)-1-(4-Fluorophenyl)-3-[(R)-3-(4-fluorophenyl)-3-hydroxypropyl]-4-(4-hydroxyphenyl)azetidin-2-one.

Suitability requirements

Resolution: NLT 1.5 between ezetimibe and R,R,S-ezetimibe diastereomer, System suitability solution

Tailing factor: NMT 1.5 for ezetimibe, System suitability solution

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

Analysis

Sample: Sample solution

Calculate the percentage of each enantiomeric or diastereomeric impurity in the portion of Ezetimibe taken:

Result = (r_U /r_T ) × 100

r_U = peak response of each impurity from the Sample solution

r_T = sum of all peak responses from the Sample solution

Acceptance criteria: The reporting threshold is 0.05%.