Simultaneous Determination of Pregabalin, Sildenafil and Its Active Metabolite in Rat Plasma Utilising SPE Followed by LC–MS–MS

Abstract

A sensitive and selective analytical method for the quantification of pregabalin, sildenafil and the active desmethyl metabolite of sildenafil (UK-103320) has been developed. The method can simultaneously quantify the three analytes within the expected in vivo concentration ranges using 50 μL of rat plasma. It utilises solid-phase extraction followed by high performance liquid chromatography coupled with tandem mass spectrometry. Quantitation in rat plasma demonstrated good accuracy and precision over the following dynamic ranges for each analyte: pregabalin (70–10,000 ng mL⁻¹), sildenafil (1–2,000 ng mL⁻¹) and UK-103320 (1–2,000 ng mL⁻¹). For each analyte, the following lower limits of quantitation were obtained: 70 ng mL⁻¹ for pregabalin and 1 ng mL⁻¹ for sildenafil and UK-103320, respectively. The method was successfully used to analyse plasma samples from rats when pregabalin and sildenafil were administered in combination.