Identificação e determinação de fármacos ansiolíticos e antiepilépticos e seus metabólitos em efluente hospitalar

Abstract

A new analytical methodology was developed in order to investigate the presence of five psychoactive drugs (anxiolytic and antiepileptics), namely, bromazepam, carbamazepine, clonazepam, diazepam, and lorazepam in the effluent of the University Hospital of Santa Maria (HUSM) of the Federal University of Santa Maria (UFSM), since these compounds are widely used in the treatment of anxiety and epilepsy. Samples were collected from two points to check the concentration of the compounds: Point A (Emergency) and point B (General Effluent - which covers the Central Library and HUSM). The method of clean-up/pre-concentration by solid phase extraction (SPE) was used to assess the occurrence of anxiolytic and antiepileptic drugs in the effluent of HUSM. Three methods were developed and validated to determine these compounds: i) high performance liquid chromatography with ultraviolet detection (HPLCUV), ii) high performance liquid chromatography with detection by mass spectrometry (LC-MS), and iii) liquid chromatography-ion trap-tandem mass spectrometry with electrospray ionization (LCMS/ MS_Qtrap). Among the methods evaluated, LC-MS/MS_Qtrap with electrospray in positive mode yielded better results. The detection limit (LOD, S/N ≥3) for lorazepam and bromazepam was 4.90±0.95 ng L-1 and for carbamazepine, clonazepam and diazepam, 6.10±1.50 ng L-1. The limit of quantification (LOQ, S/N ≥10) was 30.00±1.10 ng L-1 bromazepam , clonazepam and lorazepam; 50.00±1.81 ng L-1, carbamazepine; and 40.00±0.98 ng L-1 diazepam. The linear range of the assay (LC-MS/MS_Qtrap) was 30-1500 ng L-1 for bromazepam; 50-2500 ng L-1, carbamazepine; 30-2500 ng L-1, clonazepam; 40-2500 ng L-1, diazepam; and 30 - 2000 ng L-1, lorazepam. The correlation coefficient (R2>0.997) for all compounds. The effectiveness of the methodology was verified by recovery with the fortification of three concentration levels in triplicate samples of hospital effluent. The average recovery rates observed were: 93.9±2.1% for bromazepam; 92.6±4.2%, carbamazepine; 93.9%±3.0 clonazepam; 91.8%±6.0 for diazepam; and 93.8%±4.3 for lorazepam. The mean concentrations of psychiatric drugs detected in the effluent of the Emergency and General Effluent were respectively: 195.0±6.4 ng L-1 and 137.1±7.0 ng L-1 for bromazepam; 589.6±6.1 ng L-1, and 460.7±9.3 ng L-1, carbamazepine; 645.0±0.3 ng L-1 and 571.0± 9.9ng L-1, diazepam; 95.7±6.7 ng L-1 and 42.4±4.2 ng L-1 lorazepam; and 134.3 ± 9.8 ng L-1 and 56.9 ± 9.9 ng L-1 clonazepam. The identification of metabolites in the hospital effluent was made through (LCMS/ MS_Qtrap). The metabolites identified were: 3-hydroxybromazepam (bromazepam), 7- aminoclonazepam (clonazepam), carbamazepine 10,11-epoxide, 10-dihydroxy-10,11- dihydrocarbamazepine, iminoquinone, 2-hydroxy-carbamazepine and acridone (carbamazepine), and nordiazepam, oxazepam and temazepam (diazepam), and their fragmentation pathways were proposed. Was performed a preliminary risk assessment of anxiolytic and antiepileptic drugs with the aid of literature data and found that the carbamazepine and diazepam compounds showed the highest risk (0.85 and 0.90, respectively) among the compounds analyzed. According to the results we can say that they present medium risk requiring more attention in terms of toxicity. However, no literature data were found on the Predicted No Effect Concentration (PNEC) for bromazepam, lorazepam, clonazepam, not allowing the calculation of risk quotient (RQ) for these compounds.Therefore, we observed the occurrence of anxiolytic and antiepileptic drugs in the effluent of HUSM at concentrations in the order of ng L-1. The analytical method for LC-MS/MS_Qtrap developed for the determination of psychoactive drugs (bromazepam, carbamazepine, clonazepam, diazepam and lorazepam) in hospital effluent proved to be sensitive and selective, eliminating laborious sample handling and requiring chromatographic run of just 15 minutes. The occurrence of these drugs and environmental risks associated demonstrate the need for more efficient treatment for the hospital effluent.