Evica Antonijevic

Therapeutic and reactivating efficacy of oximes K027 and K203 against a direct acetylcholinesterase inhibitor.

As oxime-based structures are the only causal antidotes to organophosphate (OP)-inhibited acetylcholinesterase (AChE), the majority of studies on these have been directed towards their synthesis and testing. In this study, experimental bispyridinium oximes K027 and K203, which have shown promising results in the last decade of research, were examined in vivo for their therapeutic and reactivating ability in acute poisoning by the direct AChE-inhibitor dichlorvos (DDVP), used as a dimethyl OP structural model. Additionally, the efficacy of oximes K027 and K203 was compared with the efficacy of four oximes (pralidoxime, trimedoxime, obidoxime and HI-6), already used in efficacy experiments and human medicine. To evaluate therapeutic efficacy, groups of Wistar rats were treated with equitoxic doses of oximes (5% LD50, i.m.) and/or atropine (10mg/kg, i.m.) immediately after s.c. DDVP challenge (4-6 doses). Using the same antidotal protocol, AChE activity was measured in erythrocytes, diaphragm and brain 60min after s.c. DDVP exposure (75% LD50). The oxime K027 was the most efficacious in reducing the DDVP induced lethal effect in rats, while the oxime K203 was more efficacious than trimedoxime, pralidoxime and HI-6. Significant reactivation of DDVP inhibited AChE was achieved only with oxime K027 or its combination with atropine in erythocytes and the diaphragm. Moreover, the acute i.m. toxicity of oxime K027 in rats was lower than all other tested oximes. The results of this study support previous studies considering the oxime K027 as a promising experimental oxime structure for further testing against structurally-different OP compounds.

Interactions between cadmium and decabrominated diphenyl ether on blood cells count in rats—Multiple factorial regression analysis

The objective of this study was to assess toxicity of Cd and BDE-209 mixture on haematological parameters in subacutely exposed rats and to determine the presence and type of interactions between these two chemicals using multiple factorial regression analysis. Furthermore, for the assessment of interaction type, an isobologram based methodology was applied and compared with multiple factorial regression analysis. Chemicals were given by oral gavage to the male Wistar rats weighing 200-240g for 28days. Animals were divided in 16 groups (8/group): control vehiculum group, three groups of rats were treated with 2.5, 7.5 or 15mg Cd/kg/day. These doses were chosen on the bases of literature data and reflect relatively high Cd environmental exposure, three groups of rats were treated with 1000, 2000 or 4000mg BDE-209/kg/bw/day, doses proved to induce toxic effects in rats. Furthermore, nine groups of animals were treated with different mixtures of Cd and BDE-209 containing doses of Cd and BDE-209 stated above. Blood samples were taken at the end of experiment and red blood cells, white blood cells and platelets counts were determined. For interaction assessment multiple factorial regression analysis and fitted isobologram approach were used. In this study, we focused on multiple factorial regression analysis as a method for interaction assessment. We also investigated the interactions between Cd and BDE-209 by the derived model for the description of the obtained fitted isobologram curves. Current study indicated that co-exposure to Cd and BDE-209 can result in significant decrease in RBC count, increase in WBC count and decrease in PLT count, when compared with controls. Multiple factorial regression analysis used for the assessment of interactions type between Cd and BDE-209 indicated synergism for the effect on RBC count and no interactions i.e. additivity for the effects on WBC and PLT counts. On the other hand, isobologram based approach showed slight antagonism for the effects on RBC and WBC while no interactions were proved for the joint effect on PLT count. These results confirm that the assessment of interactions between chemicals in the mixture greatly depends on the concept or method used for this evaluation.

Dose-response modeling of reactivating potency of oximes K027 and K203 against a direct acetylcholinesterase inhibitor in rat erythrocytes

Inhibition of acethylcholinesterase (AChE) as a key molecular event induced by organophosphate (OP) pesticides and nerve agents presents a human health concern. In efficacy testing of experimental oximes, potential antidotes in OP poisoning, reactivation of OP-inhibited AChE is used as specific endpoint. However, according to our best knowledge, so far oximes have not been quantitatively evaluated by comprehensive benchmark dose (BMD) approach, that would improve both identification and quantification of the effect and allow more rigorous comparison of efficacies. Thus, we have examined in vivo dose-response relationship for two promising experimental oximes, K203 and K027, concerning reactivation of erythrocyte AChE inhibited by dichlorvos (DDVP). Groups of Wistar rats were treated with six different doses of oximes (i.m) immediately after DDVP challenge (s.c) and AChE was measured 60 min later. Dose-response modeling was done by PROAST software 65.5 (RIVM, The Nederlands). BMD-covariate method resulted in four-parameter model from both exponential and Hill model families as the best estimate of relationship between AChE activity and oxime dose, with potency parameter being oxime-dependent. Oxime K027 was shown to be 1.929-fold more potent considering that 58% increase in AChE activity was achived with the dose BMD58-K027 = 52 μmol/kg in contrast to BMD58-K203 = 100 μmol/kg.

Clinical and analytical experience of the National Poison Control Centre with synthetic cannabinoids

Abstract A rising number of patients are being treated for overdosing with new psychoactive substances (NPS) available at the illegal drug market in Serbia. The aim of this study was to report clinical and analytical experience of the National Poison Control Centre of Serbia (NPCC) with synthetic cannabinoids (SCs) and point to the NPS available at the illegal drug market in our country. From January 2013 to December 2016, 58 patients (aged between 14 and 25) were treated for the effects of synthetic cannabinoids at the NPCC. Tachycardia was established in 53, mydriasis in 31, somnolence, nausea, vomiting, and agitation in 16, dizziness in 10, disorientation in 9, dyspnoea and chest pain in 4, and loss of consciousness, pallor, paraesthesia, muscle twitches, and short-term memory impairment in 2 patients. After receiving symptomatic and supportive treatment in the emergency ward, all patients had fully recovered within 8 h and were discharged shortly afterwards. Another part of the study was focused on the analysis of the products known under their local street names as “Biljni tamjan” (herbal incense), “Beli slez”, and “Rainbow Special” and the analysis of urine sampled from the patients with gas chromatography - mass spectrometry and high performance liquid chromatography. The detected synthetic cannabinoids were AB-PINACA, JWH-018, JWH-122, JWH-210, 5F-AKB48, and MDMB-CHMICA in herbal products and AB-FUBINACA, AB-CHMINACA, and MDMB-CHMICA in the urine samples. Our findings have shown the great capacity of NPCC to I) monitor NPS abuse in Serbia, II) reliably detect SCs in illicit products and biological samples, and III) clinically manage the adverse effects in their users. Future commitments of the NPCC will include systematic collection of relevant data on SCs and their adverse effects, detection of changes in purity and composition of the controlled NPS-based products, and raising the public awareness of NPS to improve the effectiveness of the national Early Warning System.