Prioritisation of antidepressants based on risk-based approach of aquatic organisms in Malaysia

Numerous studies have shown the occurrence of pharmaceuticals, including antidepressants in the natural environment. This has led to further concern about their impact on non-target organisms and humans. Malaysia is one of the countries where antidepressants studies in environments are still scarce, little to none known the exposure and impacts of antidepressants studies in surface water in Malaysia. Due to the increase prevalence of mental health problem in Malaysia, the consumption of antidepressants is expected to be increase in the future. Therefore, a systematic approach is needed to identify the compounds that should be monitored in the environment. In this study, a prioritization approach was applied to 23 antidepressants compounds in Malaysia. Initially, the information on antidepressants consumption in year 2012, 2013, 2014, 2015 and 2016 were obtained from statistics report of medicines by Ministry of Health Malaysia. The studied antidepressant compounds included agomelatine, amitriptyline, bupropion, citalopram, clomipramine, desvenlafaxine, dosulepin, duloxetine, escitalopram, fluoxetine, fluvoxamine, imipramine, moclobemide, maprotiline, mianserin, mirtazapine, nortriptyline, paroxetine, sertraline, tianeptine, tranylcypromine, venlafaxine and vortioxetine. The predicted no-effect concentration (PNECs) was derived from ecotoxicological end- points and effect related to the studied antidepressant compounds. The information on fractional excretion and fractional emission of antidepressants was all obtained from previous studies to calculate Predicted Environmental Concentrations (PECs). Then, the calculated data were used to rank the antidepressant compounds in terms of risks to the environment, according to its risk quotient (PEC/PNEC). The findings of this study found that mirtazapine and sertraline were estimated to have the highest PECs in those five years. Interestingly, based on the values of risk quotient (RQ) for all antidepressant compounds, only fluoxetine and sertraline were classified to have risks to the aquatic organisms where the highest RQ recorded at 0.08 for algae, 0.22 for Daphnia and 0.06 for fish. Fluoxetine dominated the first rank as the most concern antidepressants in the aquatic environment of Malaysia. Therefore, there is a need to establish a comprehensive, nationwide monitoring program to assess the presence and trends of antidepressants in surface waters, with a focus on high-risk areas such as urban centers and locations near healthcare facilities.