Gabapentin Capsules

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

DOWNLOAD PDF HERE

1 DEFINITION

Gabapentin Capsules contain NLT 90.0% and NMT 110.0% of the labeled amount of gabapentin (C₉H₁₇NO₂).

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020)

Sample: Empty the contents of NLT 10 Capsules, and grind to a fine powder. Use a quantity of the powder, equivalent to 2 mg of gabapentin, and 200 mg of potassium bromide.

Acceptance criteria: Meet 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

Diluent: 1.2 g/L of monobasic potassium phosphate in water. Adjust with 5 N potassium hydroxide to a pH of 6.9. Mobile phase: Dissolve 1.2 g of monobasic potassium phosphate in 940 mL water. Adjust with 5 N potassium hydroxide to a pH of 6.9. Add 60 mL of acetonitrile and stir.

Standard solution: 4.0 mg/mL of USP Gabapentin RS in Diluent

Sample solution: Nominally 4.0 mg/mL of gabapentin, from the contents of NLT 20 Capsules, equivalent to 100 mg of gabapentin, in Diluent. Sonication for about 60 s may be necessary to dissolve the contents.

3.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 210 nm

Column: 4.6-mm × 25-cm; 5-µm packing L7

Flow rate: 1.2 mL/min

Injection volume: 50 µL

3.2 System suitability

Sample: Standard solution

Suitability requirements

Column efficiency: NLT 7000 theoretical plates

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

3.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of gabapentin (C₉H₁₇NO₂) in the portion of Capsules 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 Gabapentin RS in the Standard solution (mg/mL)

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

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

Dissolution 〈711〉

Medium: 0.06 N hydrochloric acid (prepared by adding 51 mL of hydrochloric acid to 10 L of water); 900 mL Apparatus 2: 50 rpm

Time: 20 min

Sample solution: Filter a portion of the solution under test using a suitable filter of 0.45-µm pore size. Mobile phase: Prepare as directed in the Assay.

Standard solution: 0.0011L mg/mL of USP Gabapentin RS in the Medium, where L is the label claim in mg/Capsule

4.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 210 nm

Column: 4.6-mm × 25-cm; 5-µm packing L7

Flow rate: 1.2 mL/min

Injection volume: 100 µL

4.2 System suitability

Sample: Standard solution

Suitability requirements

Column efficiency: NLT 7000 theoretical plates

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

4.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of gabapentin (C₉H₁₇NO₂) dissolved:

Result = (r_U /r_S ) × C_S × V × (1/L) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of the Standard solution (mg/mL)

V = volume of the Medium in the dissolution vessel, 900 mL

L = label claim (mg/Capsule)

Tolerances: NLT 80% (Q) of the labeled amount of gabapentin (C₉H₁₇NO₂) is dissolved.

Uniformity of Dosage Units 〈905〉: Meet the requirements

5 IMPURITIES

Organic Impurities

Diluent: Prepare as directed in the Assay.

Solution A: Dissolve 1.2 g of monobasic potassium phosphate in 940 mL water. Adjust with 5 N potassium hydroxide to a pH of 6.9. Add 60 mL of acetonitrile and stir.

Solution B: Dissolve 1.2 g of monobasic potassium phosphate in 700 mL water. Adjust with 5 N potassium hydroxide to a pH of 6.9. Add 300 mL of acetonitrile and stir.

Mobile phase: See Table 1.

Table 1

Standard solution: 0.04 mg/mL each of USP Gabapentin RS and USP Gabapentin Related Compound A RS in Diluent Sample solution: Nominally 20 mg/mL of gabapentin, from the contents of NLT 20 Capsules, equivalent to 500 mg of gabapentin, in Diluent. Sonication for about 30 s may be necessary.

5.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 210 nm

Column: 4.6-mm × 25-cm; 5-µm packing L7

Flow rate: 1.5 mL/min

Injection volume: 50 µL

5.2 System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0 for the gabapentin peak

Relative standard deviation: NMT 5.0% for gabapentin and gabapentin related compound A

5.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of gabapentin related compound A in the portion of Capsules taken:

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

r_U = peak response for gabapentin related compound A from the Sample solution

r_S = peak response for gabapentin related compound A from the Standard solution

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

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

Calculate the percentage of any other unspecified degradation product, relative to gabapentin content, in the portion of Capsules taken:

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

r_U = peak response for each unspecified impurity from the Sample solution

r_S = peak response for gabapentin from the Standard solution

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

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

Acceptance criteria

Gabapentin related compound A: NMT 0.4%

Any individual unspecified impurity: NMT 0.1%

Total impurities: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers. Store at controlled room temperature.

USP Reference Standards 〈11〉

USP Gabapentin RS

USP Gabapentin Related Compound A RS

2-Aza-spiro[4.5]decan-3-one.

C₉H₁₅NO                  153.22