Abstract
Consumption of psychotropic drugs is still increasing, especially in high-income countries. One of the most crucial consequences of this fact is significant release of them to the environment. Considerable amounts of atypical antipsychotics, benzodiazepines, antidepressants, and their metabolites were detected in river, lake, and sea water, as well as in tissues of aquatic organisms. Their ecotoxicity was proved by numerous studies. It should be noticed that interaction between psychotropic pharmaceuticals and radiation may lead to formation of potentially more toxic intermediates. On the other hand, photo-assisted wastewater treatment methods can be used as an efficient way to eliminate them from the environment. Many methods based on photolysis and photocatalysis were proposed and developed recently; nevertheless, the problem is still unsolved. However, according to recent studies, photocatalysis could be considered as the most promising and far more effective than regular photolysis. An overview on photolytic as well as homogenous and heterogeneous photocatalytic degradation methods with the use of various catalysts is presented. The photostability and phototoxicity of pharmaceuticals were also discussed. Various analytical methods were used for the photodegradation research, and this issue was also compared and summarized. Use of high-resolution multistage mass spectrometry (Q-TOF, ion trap, Orbitrap) was suggested. The combined techniques such as LC–MS, GC–MS, and LC–NMR, which enable qualitative and quantitative analyses in one run, proved to be the most valuable in this case. Assembling of MS/MS spectra libraries of drug molecules and their phototransformation products was identified as the future challenge.
Highlights
IntroductionPhotostability testing on benzodiazepines revealed that this group of drugs is rather susceptible to photodegradation
Psychotropic drugs are a wide group of medications used to treat symptoms of mental disorders such as depression, schizophrenia, bipolar disorder, or anxiety disorders (National Institute of Mental Health 2016a).According to a WHO report (2000), about 10 % of adults at any point in time suffer from mental disorders (Saraceno 2002), but another study showed that lifetime prevalence of such disorders can reach over 25 % (Almeida-Filho et al 1997)
The proportion of disability adjusted life years (DALY) and years of life lived with disability (YLD) caused by neuropsychiatric disorders are 12 and 31 % respectively (Saraceno 2002)
Summary
Photostability testing on benzodiazepines revealed that this group of drugs is rather susceptible to photodegradation Both chlordiazepoxide (Pathak et al 2010) and alprazolam (Cabrera et al 2005) decomposed under ICH conditions; the first one was more photolabile in basic solution, while the second one in acidic. Solution, applied solvents, presence of organic (for instance humic acids) and inorganic matrix or quantum yield (φ) of substance photochemical reaction This last parameter is characteristic for each compound and is independent of other listed factors (i.e., it should be dependent only on properties of the studied molecule; reported values of quantum yield for the same compound often vary, which is problematic; in practice, it is dependent on pH) (Challis et al 2014).
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