Orlistat

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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C₂₉H₅₃NO₅ 495.75 (IRA 1-Jan-2022)

l-Leucine, N-formyl-, 1-[(3-hexyl-4-oxo-2-oxetanyl)methyl]dodecyl ester, [2S-[2α(R*), 3β]]-;

N-Formyl-l-leucine, ester with (3S,4S)-3-hexyl-4-[(2S)-2-hydroxytridecyl]-2-oxetanone;

(S)-1-[(2S,3S)-3-Hexyl-4-oxooxetan-2-yl]tridecan-2-yl formyl-l-leucinate (IRA 1-Jan-2022) CAS RN®: 96829-58-2; UNII: 95M8R751W8.

1 DEFINITION

Orlistat contains NLT 98.0% and NMT 101.5% of orlistat (C H NO ), calculated on the anhydrous, solvent-free basis.

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K or 197A (IRA 1-Jan-2022)

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

Change to read:

3.1 Procedure

3.2 [Note - Avoid the use of plastic flasks for the preparation or containment of any solution in this analysis.]

Mobile phase: Acetonitrile, phosphoric acid, and water (860: 0.05: 140)

Standard solution: 0.5 mg/mL of USP Orlistat RS in Mobile phase. Inject immediately after preparation or store at 5°.

Sample solution: 0.5 mg/mL of Orlistat in Mobile phase. Inject immediately after preparation or store at 5°.

3.3 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 195 nm (IRA 1-Jan-2022)

Column: 3.9-mm × 15-cm; 4-μm packing L1

Flow rate: 1.0 mL/min

Injection volume: 20 μL

Run time: NLT 5.5 times the retention time of orlistat (IRA 1-Jan-2022)

3.4 System suitability

Sample: Standard solution

3.5 Suitability requirements

Relative standard deviation: NMT 1.0% (IRA 1-Jan-2022)

3.6 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of orlistat (C₂₉H₅₃NO₅) in the portion of Orlistat taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of orlistat from the Sample solution

r_S = peak response of orlistat from the Standard solution

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

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

Acceptance criteria: 98.0%–101.5% on the anhydrous, solvent-free basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.1%

4.1 Limit of Orlistat Related Compound A

Standard solution: 0.1 mg/mL of USP Orlistat Related Compound A RS in acetone

Sample solution: 50 mg/mL of Orlistat in acetone

Chromatographic system

(See Chromatography 〈621〉, General Procedures, Thin-Layer Chromatography.)

Mode: TLC

Adsorbent: 0.25-mm layer of chromatographic silica gel mixture

Application volume: 10 μL

Developing solvent system: Toluene and ethyl acetate (4:1)

Detection solution: Transfer 2.5 g of phosphomolybdic acid and 1 g of ceric sulfate into a 100-mL volumetric flask, and dissolve in and dilute with methanol to volume.

Analysis

Samples: Standard solution and Sample solution

Remove the plate, and air-dry it thoroughly. Spray the dried plate with Detection solution, and place the plate in an oven at 120° for 30 min.

Acceptance criteria: Any secondary spot from the Sample solution corresponding to orlistat related compound A is not more intense than the corresponding spot from the Standard solution (0.2%).

4.2 Limit of Orlistat Related Compound B

Standard solution: 0.025 mg/mL of USP Orlistat Related Compound B RS in methylene chloride

Sample solution: 50 mg/mL of Orlistat in methylene chloride

Spiked sample solution: 50 mg/mL of Orlistat in Standard solution

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: GC

Detector: Flame ionization

Column: 0.32-mm × 30-m fused silica, coated with a 0.25-μm G27 stationary phase

Temperatures

Injector: 270°

Detector: 280°

Column: See Table 1.

Table 1

System suitability

Sample: Standard solution

Suitability requirements

Relative standard deviation: NMT 10.0%

Analysis

Samples: Standard solution, Sample solution, and Spiked sample solution

Calculate the percentage of orlistat related compound B in the portion of Orlistat taken:

Result = {r_U/[r_SP − r_U × (C_T/C_U)]} × (C_S/C_U) × 100

r_U = peak response of orlistat related compound B from the Sample solution

r_SP = peak response of orlistat related compound B from the Spiked sample solution

C_T = concentration of Orlistat in the Spiked sample solution (mg/mL)

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

C_S = concentration of USP Orlistat Related Compound B RS in the Standard solution (mg/mL)

Acceptance criteria: NMT 0.05%

Change to read:

4.3 Organic Impurities

[Note-Avoid the use of plastic flasks for the preparation or containment of any solution in this analysis.]

Mobile phase, Standard solution, and Sample solution: Prepare as directed in the Assay.

System suitability solution: 10 μg/mL of USP Orlistat RS and 0.1 μg/mL of USP Orlistat Related Compound C RS in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 195 nm

Column: 3.9-mm × 15-cm; 4-μm packing L1

Flow rate: 1.0 mL/min

Injection volume: 20 μL

Run time: NLT 5.5 times the retention time of orlistat (IRA 1-Jan-2022)

System suitability

Sample: System suitability solution

Suitability requirements

Relative standard deviation: NMT 5.0% (IRA 1-Jan-2022) for the orlistat peak

Signal-to-noise ratio: NLT 3 for orlistat related compound C

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each impurity other than orlistat related compound A, orlistat related compound B, orlistat related compound

D, orlistat open ring amide, and orlistat related compound E in the portion of Orlistat 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 orlistat from the Standard solution

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

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

F = relative response factor (see Table 2)

Acceptance criteria: See Table 2.

Table 2

^a N-Formyl-l-leucine.

^b (2S,3R,5S)-5-[(Formyl-l-leucyl)oxy]-2-hexyl-3-hydroxyhexadecanoic acid. (IRA 1-Jan-2022)

^c Coelutes in this LC system, determined using Limits of Orlistat Related Compound D and Orlistat Open Ring Amide.

^d (7S,8S,10S)-8-Hydroxy-7-{[(R)-1-phenylethyl]carbamoyl}henicosan-10-yl formyl-l-leucinate. (IRA 1-Jan-2022)

^e (S)-1-[(2S,3S)-3-Hexyl-4-oxooxetan-2-yl]tridecan-2-yl formyl-d-leucinate. (IRA 1-Jan-2022)

^f Sum of results obtained in the tests for Limit of Orlistat Related Compound A, Limit of Orlistat Related Compound B, Organic Impurities, Limits of Orlistat Related Compound D and Orlistat Open Ring Amide, and Limit of Orlistat Related Compound E.

Change to read:

4.4 Limits of Orlistat Related Compound D and Orlistat Open Ring Amide

Mobile phase: Methanol and water (830:170)

System suitability solution: 4 mg/mL of USP Orlistat RS and 2.5 μg/mL of orlistat related compound D prepared by dissolving a suitable amount of USP Orlistat RS and diluting USP Orlistat Related Compound D Solution RS in acetonitrile (IRA 1-Jan-2022)

Standard solution: 5.0 mg/mL of USP Orlistat RS in acetonitrile

Sample solution: 5.0 mg/mL of Orlistat in acetonitrile

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 205 nm

Column: 4.0-mm × 25-cm; 5-μm packing L7

Flow rate: 0.6 mL/min

Injection volume: 20 μL

Run time: NLT 1.4 times the retention time of orlistat (IRA 1-Jan-2022)

System suitability

Sample: System suitability solution

Suitability requirements

Relative standard deviation: NMT 5.0% (IRA 1-Jan-2022) for the orlistat peak

Signal-to-noise ratio: NLT 3 for the orlistat related compound D peak

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of orlistat related compound D and orlistat open ring amide in the portion of Orlistat taken:

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

r_U = peak response of orlistat related compound D or orlistat open ring amide from the Sample solution

r_S = peak response of orlistat from the Standard solution

C_S = concentration of USP Orlistat RS in the Standard solution (mg/mL(IRA 1-Jan-2022))

C_U = concentration of Orlistat in the Sample solution (mg/mL (IRA 1-Jan-2022))

F = relative response factor (see Table 3)

Acceptance criteria: See Table 3.

Table 3

^a (7S,8S,10S)-8-Hydroxy-7-{[(R)-1-phenylethyl]carbamoyl}henicosan-10-yl formyl-l-leucinate. (IRA 1-Jan-2022)

Change to read:

4.5 Limit of Orlistat Related Compound E

Buffer: 0.4 N borate solution, adjusted to a pH of 10.2

Derivatizing agent: o-Phthalaldehyde (OPA) solution. [Note—If unable to obtain commercially, the Derivatizing agent can be prepared as 1% each of 3-mercaptopropionic acid and o-phthalaldehyde in 0.4 M borate buffer solution.]

Solution A: Transfer 4.1 g of sodium acetate trihydrate and 40 mg of ethylenediaminetetraacetic acid (EDTA) into a 1-L volumetric flask.

Dissolve in 950 mL of water, and adjust with 0.1 N sodium hydroxide to a pH of 7.2. Dilute with water to volume, add 2.5 mL of tetrahydrofuran, and mix. Filter, and degas.

Solution B: Transfer 2.7 g of sodium acetate trihydrate and 40 mg of EDTA into a 1-L volumetric flask. Dissolve in 200 mL of water, and adjust with 0.1 N sodium hydroxide to a pH of 7.2. Add 800 mL of acetonitrile, filter, and degas.

Mobile phase: See Table 4.

Table 4

Standard solution: Transfer a weighed quantity of about 0.2 mg of USP Orlistat Related Compound E RS into a 20-mL headspace vial. Add 10mL of 4 N sodium hydroxide, and close the vial. Heat the vial to 100° for 1 h, then allow to cool to room temperature. Transfer 2 mL of the resulting solution into a 50-mL volumetric flask, and dilute with water to volume. To 0.5 mL of this solution add 2.0 mL of Buffer and 0.5 mL of Derivatizing agent.

Sample solution: Proceed as directed for the Standard solution, except use 25 mg of Orlistat to replace the 0.2 mg of USP Orlistat Related Compound E RS.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: Fluorescence 340 nm (excitation); 450 nm (emission)

Columns

Guard: 2.1-mm × 2-cm; 5-μm packing L1

Analytical: 2.1-mm × 20-cm; 5-μm packing L1

Flow rate: 0.5 mL/min

Injection volume: 20 μL

System suitability

Sample: Standard solution

Suitability requirements

Relative standard deviation: NMT 6.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of orlistat related compound E in the portion of Orlistat taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of orlistat related compound E from the Sample solution

r_S = peak response of orlistat related compound E from the Standard solution

C_S = concentration of USP Orlistat Related Compound E RS in the Standard solution (mg/mL)

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

Acceptance criteria: NMT 0.2%

5 SPECIFIC TESTS

Optical Rotation 〈781S〉, Procedures, Specific Rotation

Sample solution: 30 mg/mL in dehydrated alcohol

Acceptance criteria: Between −48.0° and −51.0°, at 20°

Water Determination 〈921〉, Method I, Method Ic: NMT 0.2%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers between 2° and 8°.

Change to read:

USP Reference Standards 〈11〉

USP Orlistat RS

USP Orlistat Related Compound A RS

(3S,4S)-3-Hexyl-4-[(R)-2-hydroxytridecyl]oxetan-2-one. (IRA 1-Jan-2022)

C₂₂H₄₂O₃ 354.58 (IRA 1-Jan-2022)

USP Orlistat Related Compound B RS

Diisopropyl hydrazine-1,2-dicarboxylate.

C₈H₁₆N₂O₄ 204.23 (IRA 1-Jan-2022)

USP Orlistat Related Compound C RS

Triphenylphosphine oxide.

C₁₈H₁₅OP 278.29

USP Orlistat Related Compound D Solution RS

Orlistat related compound D;

(3S,4R,6S)-3-Hexyl-2-oxo-6-undecyltetrahydro-2H-pyran-4-yl formyl-l-leucinate.

C₂₉H₅₃NO₅ 495.75 (IRA 1-Jan-2022)

USP Orlistat Related Compound E RS

(S)-1-[(2S,3S)-3-Hexyl-4-oxooxetan-2-yl]tridecan-2-yl formyl-l-isoleucinate. (IRA 1-Jan-2022)

C₂₉H₅₃NO₅ 495.75 (IRA 1-Jan-2022)