Pregabalin

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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C₈H₁₇NO₂ 159.23 

(S)-3-(Aminomethyl)-5-methylhexanoic acid CAS RN®: 148553-50-8. 

1 DEFINITION 

Pregabalin contains NLT 98.0% and NMT 102.0% of pregabalin (C₈H₁₇NO₂), calculated on the dried basis

2 IDENTIFICATION 

Change to read: 

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

Mobile phase: Acetonitrile and water (5:95) 

Standard solution: 2.0 mg/mL of USP Pregabalin RS in Mobile phase 

Sample solution: 2.0 mg/mL of Pregabalin in Mobile phase 

Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 205 nm 

Column: 4.6-mm × 25-cm; 5-µm packing L1 

Temperatures 

Autosampler: 10° 

Column: 25° 

Flow rate: 1.0 mL/min 

Injection volume: 20 µL 

Run time: NLT 2.5 times the retention time of pregabalin 

System suitability 

Sample: Standard solution 

Suitability requirements 

Tailing factor: NMT 1.5 

Relative standard deviation: NMT 0.73% 

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of pregabalin (C₈H₁₇NO₂) in the portion of Pregabalin taken: 

Result = (r_U/r_S) × (C_S/C_U) × 100 

r_U = peak response of pregabalin from the Sample solution 

r_S = peak response of pregabalin from the Standard solution 

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

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

Acceptance criteria: 98.0%–102.0% on the dried basis 

4 IMPURITIES 

Residue on Ignition 〈281〉: NMT 0.1% 

Change to read: 

Chloride and Sulfate 〈221〉, Chloride 

Standard solution: Prepare as directed in the chapter using 1.4 mL.  

Sample solution: Prepare as directed in the chapter using 1.0 g  of Pregabalin. 

Acceptance criteria: The turbidity produced in the Sample solution is NMT that produced in the Standard solution (0.1%). Change to read: 

Organic Impurities 

Buffer: 0.04 M dibasic ammonium phosphate. Adjust with phosphoric acid to a pH of 6.5. 

Solution A: Methanol and Buffer (20:80) 

Solution B: Methanol and acetonitrile (10:90) 

Mobile phase: See Table 1. 

Table 1 

Sensitivity solution: 0.005 mg/mL of USP Pregabalin RS in water  

Standard solution: 0.01 mg/mL of USP Mandelic Acid RS and 0.05 mg/mL each of USP Pregabalin RS and USP Pregabalin Related Compound C RS in water 

Sample solution: 10.0 mg/mL of Pregabalin in water 

Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 210 nm 

Column: 4.6-mm × 25-cm; 5-µm packing L1 

Column temperature: 35° 

Flow rate: 1.0 mL/min 

Injection volume: 20 µL 

System suitability 

Samples: Sensitivity solution and  Standard solution 

Suitability requirements 

Relative standard deviation: NMT 5% for mandelic acid, pregabalin, and pregabalin related compound C, Standard solution Signal-to-noise ratio: NLT 10, Sensitivity solution  

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of mandelic acid and pregabalin related compound C in the portion of Pregabalin taken: 

Result = (r_U/r_S) × (C_S/C_U) × 100 

r_U = peak response of mandelic acid or pregabalin related compound C from the Sample solution

r_S = peak response of mandelic acid or pregabalin related compound C from the Standard solution 

C_S = concentration of USP Mandelic Acid RS or USP Pregabalin Related Compound C RS in the Standard solution (mg/mL)

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

Calculate the percentage of any individual unspecified impurity in the portion of Pregabalin taken: 

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

r_U = peak response of each impurity from the Sample solution

r_S = peak response of pregabalin from the Standard solution

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

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

F = relative response factor (see Table 2) 

Acceptance criteria: See Table 2. The reporting threshold is 0.05%. Table 

^a 3-Isobutylpentanedioic acid. 

^b 3-(2-Amino-2-oxoethyl)-5-methylhexanoic acid. 

Change to read: 

Enantiomeric Purity 

Buffer: Triethylamine and water (7.2:1000). Adjust with 50% (v/v) phosphoric acid to a pH of 3.0. 

Mobile phase: Acetonitrile and Buffer (38:62) 

Derivatizing reagent solution: 3 mg/mL of Marfey's reagent in acetone 

Sensitivity stock solution: 0.5 µg/mL of USP Pregabalin RS prepared as follows. Transfer an appropriate amount of USP Pregabalin RS to a suitable volumetric flask. Dissolve in 50% of the final volume of water and dilute with acetone to volume. 

Sensitivity solution: Transfer 1.0 mL of the Sensitivity stock solution to a 10.0-mL volumetric flask, add 0.6 mL of the Derivatizing reagent solution and 100 µL of 1 M sodium bicarbonate, and heat at 55° for about 1 h. Allow to cool to room temperature and dilute with water to volume.  

Standard stock solution: 1 mg/mL of USP Pregabalin RS and 0.05 mg/mL of USP Pregabalin Related Compound A RS prepared as follows. Transfer appropriate amounts of USP Pregabalin RS and USP Pregabalin Related Compound A RS to a suitable volumetric flask. Dissolve in 50% of the final volume of water and dilute with acetone to volume. 

Standard solution: Transfer 0.5 mL of the Standard stock solution to a 5.0-mL volumetric flask, add 0.3 mL of the Derivatizing reagent solution and 50 µL of 1 M sodium bicarbonate, and heat at 55° for about 1 h. Allow to cool to room temperature and dilute with water to volume. Sample stock solution: 1 mg/mL of Pregabalin prepared as follows. Transfer an appropriate amount of Pregabalin to a suitable volumetric flask. Dissolve in 50% of the final volume of water and dilute with acetone to volume. 

Sample solution: Transfer 0.5 mL of the Sample stock solution to a 5.0-mL volumetric flask, add 0.3 mL of the Derivatizing reagent solution and 50 µL of 1 M sodium bicarbonate, and heat at 55° for about 1 h. Allow to cool to room temperature and dilute with water to volume. Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 340 nm 

Column: 4.6-mm × 25-cm; 5-µm packing L1 

Temperatures 

Autosampler: 10° 

Column: 25° 

Flow rate: 2.0 mL/min 

Injection volume: 20 µL 

Run time: NLT 3.8 times the retention time of pregabalin 

System suitability 

Samples: Sensitivity solution and  Standard solution 

[Note—The relative retention times for pregabalin and pregabalin related compound A are 1.0 and 1.2, respectively.]  Suitability requirements 

Resolution: NLT 3.0 between pregabalin and pregabalin related compound A, Standard solution  

Relative standard deviation: NMT 5.0% for pregabalin related compound A, Standard solution 

Signal-to-noise ratio: NLT 10, Sensitivity solution  

Analysis 

Sample: Sample solution 

Calculate the percentage of pregabalin related compound A in the portion of Pregabalin taken: 

Result = (r_U/r_T) × 100 

r_U = peak response of pregabalin related compound A from the Sample solution 

r_T = sum of the peak responses of pregabalin and pregabalin related compound A from the Sample solution 

Acceptance criteria: NMT 0.15% 

5 SPECIFIC TESTS 

Loss on Drying 〈731〉 

Analysis: Dry at 105° for 3 h. 

Acceptance criteria: NMT 0.5% 

6 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Preserve in tight containers. Protect from light and store at NMT 25°. 

USP Reference Standards 〈11〉 

USP Mandelic Acid RS 

USP Pregabalin RS 

USP Pregabalin Related Compound A RS 

(R)-3-(Aminomethyl)-5-methylhexanoic acid. 

C₈H₁₇NO₂ 159.23 

USP Pregabalin Related Compound C RS 

4-Isobutylpyrrolidin-2-one. 

C₈H₁₅NO 141.21