A Rapid and Simple Analytical Methodology for Therapeutic Drug Monitoring of Selective Serotonin Reuptake Inhibitors in Human Plasma by High‐Pressure Liquid Chromatography

ABSTRACT This study aimed to develop a fast, sensitive, and easy chromatographic analysis technique to determine therapeutic plasma concentrations of selective serotonin reuptake inhibitors citalopram, paroxetine, duloxetine, fluvoxamine, fluoxetine, and sertraline) by high‐pressure liquid chromatography. Chromatographic separation was conducted using a Zorbax Eclipse XDB C18 column. The mobile phase consisted of a 20 mM sodium phosphate buffer and acetonitrile in a ratio of 60:40 (v/v), flowing at a rate of 1 mL/min with a gradient program. Detection was achieved through a combination of a photodiode array detector set at 220 nm and a fluorescence detector with excitation at 230 nm and emission at 325 nm. Two different plasma extraction methods, solid‐phase extraction and salt‐assisted liquid‐phase extraction, were studied and compared for their effectiveness in preparing samples for chromatographic analysis of selective serotonin reuptake inhibitors. The detection and determination limits of molecules were 3.0 and 25 ng/mL, respectively. The method was linear (“ r 2 ” values were calculated between 0.9961 and 0.9994) over the concentration range of 25–200 ng/mL for all molecules. Accordingly, the recovery rates of the SPE extraction method were calculated in the range of 71.38%–93.60%, intraday repeatability was calculated in the range of 7.18%–10.83%, and interday repeatability was calculated in the range of 8.09%–11.65%. As a result of the salt‐assisted liquid‐phase extraction, retrieval rates are in the range of 74.84%–93.83%, intraday repeatability is 5.86%–7.05%, and interday repeatability is 7.32%–10.80%. Although these two extraction methods, which have been developed and validated, can be used to determine the plasma concentration of the molecules, however obtaining higher recovery rates, consuming less solvent, and being faster and lower cost are the advantages of the salt‐assisted liquid‐phase extraction compared to the solid‐phase extraction method.