Gabapentin Compounded Oral Suspension

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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1 DEFINITION

Gabapentin Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of gabapentin (C₉H₁₇NO₂). 

Prepare Gabapentin Compounded Oral Suspension 100 mg/mL from powder as follows (see Pharmaceutical Compounding—Nonsterile Preparations 〈795〉).

^a Gabapentin 300-mg capsules, Apotex Inc., Weston, Ontario.

^b Medisca Pharmaceutique Inc., Montréal, Quebec.

Transfer the Gabapentin powder or empty the contents of the capsules into a suitable container and triturate to a ne powder. Add a small amount of Vehicle, and mix well to form a smooth paste. Add a sufficient amount of Vehicle to make the contents pourable. Transfer the contents stepwise and quantitatively to a calibrated container using the remainder of the Vehicle. Add a sufficient amount of Vehicle to bring to nal volume, and mix well.

2 ASSAY

Procedure

Solution A: 10 mM solution of monobasic potassium phosphate adjusted with 1 M sodium hydroxide to a pH of 6.2

Mobile phase: Acetonitrile and Solution A (84:16)

Standard solution: 2.5 mg/mL of USP Gabapentin RS in Mobile phase

Sample solution: Add 0.05 mL of Oral Suspension to 0.45 mL of methanol, and vortex for 20 s. Centrifuge at 10,000 rpm for 15 min, and transfer 0.1 mL of the supernatant to a 1.5-mL centrifuge tube. Add 0.3 mL of Mobile phase, vortex for 10 s, and then transfer to HPLC vials.

2.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 210 nm

Column: 3.0-mm × 10-cm; 5-μm packing L8

Temperatures

Autosampler: 5°

Column: 40°

Flow rate: 0.8 mL/min

Injection volume: 20 µL

2.2 System suitability

Sample: Standard solution

[Note—The retention time for gabapentin is approximately 2.9 min.]

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0% for replicate injections

2.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of gabapentin (C₉H₁₇NO₂) in the portion of Oral Suspension taken: 

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

r_U = peak response of gabapentin from the Sample solution

r_S = peak response of 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: 90.0%–110.0%

3 SPECIFIC TESTS

pH 〈791〉: 5.0–6.0

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Package in tight, light-resistant containers. Store at controlled room temperature. Do not refrigerate.

Beyond-Use Date: NMT 90 days after the date on which it was compounded when stored at controlled room temperature

Labeling: Label it to indicate that it is to be well shaken before use and to state the Beyond-Use Date.

USP Reference Standards 〈11〉

USP Gabapentin RS _{(USP 1-Dec-2021)}