Non-derivatization method for the determination of gabapentin in pharmaceutical formulations, rat serum and rat urine using high performance liquid chromatography coupled with charged aerosol detection

A simple and sensitive isocratic reverse-phase high performance liquid chromatography method coupled with charged aerosol detection (HPLC-CAD) was developed and validated for the determination of gabapentin concentrations in a pharmaceutical formulation and in biological samples (rat serum and urine). Biological samples were simply treated with acetonitrile and directly injected into the HPLC without any further extraction or derivatization procedures. The separation was achieved on a GraceSmart RP-C18 packed column (250 ×4.6 mm, 5 μm) using a methanol-water (55:45, v/v) mobile phase at a flow rate of 1.1 mL/min at 30 °C. The total run time was less than 8 min. The standard calibration curves were linear (r² > 0.998) over the range of 2-300 μg/mL for the pharmaceutical formulation, 25-800 μg/mL for rat serum and 50-1600 μg/mL for rat urine. The limits of detection (signal/noise = 3) were 0.5 μg/mL, 10 μg/mL and 15 μg/mL for pharmaceutical formulation, serum and urine, respectively. The intra-day and inter-day precisions in the pharmaceutical formulation analysis ranged between 2.7-3.9% and 3.1-4.4%, respectively. In the rat serum analysis, the intra-day and inter-day precision ranges were 3.5-4.7% and 3.0-9.0%, respectively, while the rat urine analysis intra-day and inter-day precision ranges were 1.9-7.6% and 4.2-9.9%, respectively. The developed HPLC-CAD method successfully determined gabapentin concentrations in commercial gabapentin tablets, as well as in rat serum and urine samples after drug administration.