Development and optimization of a new method to determine antidepressants in oral fluid by microextraction by packed sorbent and analysis by GC-MS/MS

Abstract

Between 2013 and 2016, the consumption of antidepressants doubled in Portugal, with around 30 million packages of medication for depression, anxiety and other mental health problems dispensed annually. This phenomenon has even given rise to several alerts, which was highlighted in the 2017 report of the National Program for Mental Health, as Portugal has one of the highest rates of mental illness in Europe1. Therapeutic drug monitoring is well established for a small number of drugs, namely for those where a direct relationship between concentration and pharmacological effect at the site of action exists, which in turn is predictably reflected in the response. Drug concentrations in the various biological fluids are used in conjunction with other clinical observation measures to assess the patient's condition, and further support the individualization of therapy. Within this group of drugs targeted for monitoring are antidepressants. In recent years, oral fluid has gained more and more importance in the field of therapeutic drug monitoring, as a non-invasive and painless alternative to traditionally sampled specimens (e.g. blood, plasma). MEPS is a miniaturized solid-phase extraction (SPE) and therefore has a great advantage in the reduced operating volumes and consequently lower amounts of sample and organic solvents are required. As a result, MEPS decreases the time required for extraction, clean-up and concentration of analytes. This is the first work that uses MEPS as sample preparation technique for the determination of antidepressants and metabolites in oral fluid samples (250 µL). The simple extraction procedure proved to be efficient, requiring only 250 µL of biological sample, making it an excellent alternative for the determination of these compounds in routine clinical and forensic toxicology laboratories and for therapeutic monitoring purposes.