There is a great diversity of the acute drugs overdose cases in clinical toxicology. Clinical situation is complicated by the coexistence of factors predisposing to the development o f adverse drug reactions (chronic use of drugs, polypharmacy, alcohol or drugs dependence, nutritional disorders) and by the presence of chronic organ damage, especially the liver and the kidney. The aim of this study w as to evaluate whether there are sensitive plasma markers belonging to the antioxidant system in patients exposed to various xenobiotics. We measured the activity of antioxidant parameters: catalase (CAT), glutathione peroxidase (GPX3), glutathione (GSH), sulfhydryl groups (-SH), carbonyl groups (=CO) and free radicals (2,2-diphenyl-1-picrylhydrazyl, DPPH, assay) in serum of 49 patients with acute intoxication caused by carbamazepine (CBZ, n = 9), mixed drug intoxication (MDI) (n = 9), alcohol withdrawal syndrome (AWS, n = 9), acetaminophen (APAP, n = 7), tricyclic antidepressants (TCAs) (n = 5), valproic acids (VA, n = 4), narcotics (N, n = 3), and three others (benzodiazepines, BZD, n = 2; barbiturates, n = 1). The results were compared w ith the parameters of not intoxicated patients (n = 39). All patients had lower catalase activity in comparison to the control group (41.9 ± 16.5 vs. 196.0 ± 82.2 U/mg protein, p = 0.000), while the increase of GSH level was particularly apparent only in patients with AWS (391.3 ± 257.9 pmol/mg protein) compared to the control group (171.4 ± 88.4 pmol/mg protein, p = 0.034) and to patients intoxicated with carbamazepine (152.8 ± 102.5 pmol/mg protein, p = 0.027). Some differences, but without statistical significance, were also observed in GPX3 activity between different groups of poisoned patients
