Trimedoxime is a bisquaternary oxime that is widely used in the treatment of organophosphorous poisoning caused by tabun and paraoxon. We tested its affinity to acetylcholinesterase (AChE), its mechanism of interaction and effect on the cholinergic system of the rat bladder. The half maximal inhibitory concentration (IC50) of trimedoxime to recombinant AChE was found to be 82.0 mM ± 30.1 mM. This represents a weak inhibition. Its interaction with AChE seems to be very similar to obidoxime - one aromatic nucleus interacts with the peripheral anionic site and the other with the residues TYR337 and TYR341 inside the cavity. Also the oxime moiety is moving towards the catalytic triade ready for the reactivation of the inhibited AChE. In the organ bath experiment no significant effect of trimedoxime was observed on the contraction of the detrusor caused by the muscarinic agonist metacholine.

• Klíčová slova
• acetylcholinesterase, trimedoxime, antidote, muscaricnic receptors, reactivation,
• MeSH
• acetylcholinesterasa farmakokinetika   farmakologie   účinky léků   MeSH
• antidota farmakologie   terapeutické užití   MeSH
• cholinergní antagonisté farmakokinetika   farmakologie   terapeutické užití   MeSH
• cholinergní látky farmakologie   imunologie   izolace a purifikace   MeSH
• experimenty na zvířatech MeSH
• financování organizované MeSH
• močový měchýř MeSH
• organofosforové sloučeniny farmakokinetika   farmakologie   toxicita   MeSH
• pesticidy farmakokinetika   farmakologie   toxicita   MeSH
• potkani Sprague-Dawley MeSH
• reaktivátory cholinesterázy farmakokinetika   farmakologie   terapeutické užití   MeSH
• receptory muskarinové účinky léků   MeSH
• synergismus léků MeSH
• trimedoxim farmakokinetika   farmakologie   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH

K027 [1-(4-hydroxyiminomethylpyridinium)-3-(4-carbamoylpyridinium)-propane dibromide] is a promising new reactivator of organophosphate- or organophosphonate-inhibited acetylcholinesterase (AChE) with low acute toxicity and broad spectrum efficacy. The aim of the present study was to compare the pharmacokinetics of both compounds. Male Wistar rats (body weight = 320 ± 10 g) were administered a single intramuscular dose of K027 (22.07 mg kg(-1)) and an equimolar dose of trimedoxime. Blood was collected at various time intervals until 180 min. Plasma samples were analyzed by reversed-phase HPLC with ultraviolet (UV) detection. The recovery of both oximes from the plasma was approximately 90% and a linear relationship (R(2) > 0.998) was observed between the peak areas and concentrations of calibrated standards in the range 1-100 µg ml(-1). Near-identical plasma profiles were obtained for both compounds. No differences were found in the mean ± SD values of C(max) (18.6 ± 2.5 vs 20.0 ± 6.3 µg ml(-1), P = 0.72) and AUC(0-180min) (2290 ± 304 vs 2269 ± 197 min µg ml(-1), P = 0.84). However, the percentage coefficient of variation of the first-order rate constant of absorption (k(a)) was 3-fold higher (P < 0.01) providing evidence for more erratic absorption of intramuscular trimedoxime as compared with K027. In conclusion, oxime K027 might have superior pK properties that may be translated in its faster absorption and subsequent tissue distribution.

• MeSH
• injekce intramuskulární MeSH
• krysa rodu rattus MeSH
• oximy krev   farmakokinetika   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny krev   farmakokinetika   MeSH
• reaktivátory cholinesterázy krev   farmakokinetika   MeSH
• spektrofotometrie ultrafialová metody   MeSH
• tkáňová distribuce MeSH
• trimedoxim krev   farmakokinetika   MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH
• srovnávací studie MeSH

Up to now, intensive attempts to synthesize a universal reactivator able to reactivate cholinesterases inhibited by all types of nerve agents/organophosphates were not successful. Therefore, another approach using a combination of two reactivators differently reactivating enzyme was used: in rats poisoned with tabun and treated with combination of atropine (fixed dose) and different doses of trimedoxime and HI-6, changes of acetylcholinesterase activities (blood, diaphragm and different parts of the brain) were studied. An increase of AChE activity was observed following trimedoxime treatment depending on its dose; HI-6 had very low effect. Combination of both oximes showed potentiation of their reactivation efficacy; this potentiation was expressed for peripheral AChE (blood, diaphragm) and some parts of the brain (pontomedullar area, frontal cortex); AChE in the basal ganglia was relatively resistant. These observations suggest that the action of combination of oximes in vivo is different from that observed in vitro.

• MeSH
• acetylcholinesterasa krev   metabolismus   MeSH
• aktivace enzymů účinky léků   MeSH
• centrální nervový systém účinky léků   enzymologie   metabolismus   MeSH
• kombinovaná farmakoterapie MeSH
• krysa rodu rattus MeSH
• organofosfáty MeSH
• otrava organofosfáty MeSH
• oximy aplikace a dávkování   farmakologie   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny aplikace a dávkování   farmakologie   MeSH
• reaktivátory cholinesterázy aplikace a dávkování   farmakologie   MeSH
• trimedoxim aplikace a dávkování   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Organophosphorus (OP) compounds are used as both chemical weapons and pesticides. However, these agents are very dangerous and toxic to humans, animals, and the environment. Thus, investigations with reactivators have been deeply developed in order to design new antidotes with better efficiency, as well as a greater spectrum of action in the acetylcholinesterase (AChE) reactivation process. With that in mind, in this work, we investigated the behavior of trimedoxime toward the Mus musculus acetylcholinesterase (MmAChE) inhibited by a range of nerve agents, such as chemical weapons. From experimental assays, reactivation percentages were obtained for the reactivation of different AChE-OP complexes. On the other hand, theoretical calculations were performed to assess the differences in interaction modes and the reactivity of trimedoxime within the AChE active site. Comparing theoretical and experimental data, it is possible to notice that the oxime, in most cases, showed better reactivation percentages at higher concentrations, with the best result for the reactivation of the AChE-VX adduct. From this work, it was revealed that the mechanistic process contributes most to the oxime efficiency than the interaction in the site. In this way, this study is important to better understand the reactivation process through trimedoxime, contributing to the proposal of novel antidotes.

• MeSH
• acetylcholinesterasa metabolismus   MeSH
• antidota farmakologie   MeSH
• cholinesterasové inhibitory metabolismus   farmakologie   MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• myši MeSH
• nervová bojová látka chemie   MeSH
• organofosforové sloučeniny chemie   MeSH
• oximy chemie   MeSH
• reaktivátory cholinesterázy chemie   farmakologie   MeSH
• trimedoxim farmakologie   terapeutické užití   MeSH
• výpočetní biologie metody   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The ability of two newly developed bispyridinium oximes (K920, K923) to reduce tabun-induced acute neurotoxic signs and symptoms was compared with the oxime K203 and trimedoxime using a functional observational battery (FOB). The neuroprotective effects of the oximes studied combined with atropine on rats poisoned with tabun at a sublethal dose (130 μg/kg i.m.; 80% of LD50 value) were evaluated. Tabun-induced neurotoxicity was monitored by FOB at 2 h after tabun administration. The results indicate that all tested oximes combined with atropine enable tabun-poisoned rats to survive till the end of experiment while one non-treated tabun-poisoned rat died within 2 h. Both newly developed oximes (K920, K923) combined with atropine were able to markedly decrease tabun-induced neurotoxicity in the case of sublethal poisoning although they did not eliminate all tabun-induced acute neurotoxic signs and symptoms. Their ability to decrease tabun-induced acute neurotoxicity did not prevail the neuroprotective efficacy of trimedoxime and the oxime K203. Therefore, the newly developed oximes are not suitable for the replacement of currently available oximes (especially trimedoxime) in the treatment of acute tabun poisonings.

• MeSH
• molekulární struktura MeSH
• neuroprotektivní látky chemie   terapeutické užití   MeSH
• neurotoxické syndromy etiologie   prevence a kontrola   MeSH
• organofosfáty toxicita   MeSH
• oximy chemie   terapeutické užití   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny chemie   terapeutické užití   MeSH
• reaktivátory cholinesterázy chemie   terapeutické užití   MeSH
• trimedoxim chemie   terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH

The penetration of acetylcholinesterase reactivators (oximes) into the central nervous system is typically restricted by the blood-brain barrier. Although oximes are highly hydrophilic compounds, some contradictory results confirming permeation into the brain exist. The aim of this study is to verify the penetration of oximes through the blood-brain barrier and to detect their levels achieved in different brain regions 60 min after the administration. It was confirmed that oximes are able to penetrate into the brain after injection of therapeutic doses corresponding with 5% of LD(50). The level in whole brain was 0.58% for trimedoxime and 0.85% for the experimental drug oxime K074 as the percentage of their plasma concentration. The highest concentration was found in frontal cortex (trimedoxime 2.27%; oxime K074 0.95%) and lowest in basal ganglia (trimedoxime 0.86%; oxime K074 0.42%). Entry of oximes into the brain is minimal, but some low reactivation effect should be expected. The reactivation potency of oximes might be higher or lower, depending on the real oxime concentration in a given area.

• MeSH
• butany aplikace a dávkování   krev   izolace a purifikace   farmakokinetika   farmakologie   MeSH
• injekce intramuskulární MeSH
• kalibrace MeSH
• krysa rodu rattus MeSH
• limita detekce MeSH
• molekulární struktura MeSH
• mozek metabolismus   MeSH
• oximy aplikace a dávkování   krev   izolace a purifikace   farmakokinetika   farmakologie   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny aplikace a dávkování   krev   izolace a purifikace   farmakokinetika   farmakologie   MeSH
• reaktivátory cholinesterázy aplikace a dávkování   krev   izolace a purifikace   farmakokinetika   farmakologie   MeSH
• referenční standardy MeSH
• regresní analýza MeSH
• reprodukovatelnost výsledků MeSH
• tkáňová distribuce MeSH
• trimedoxim aplikace a dávkování   krev   izolace a purifikace   farmakokinetika   farmakologie   MeSH
• vysokoúčinná kapalinová chromatografie přístrojové vybavení   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Tabun (O-ethyl-N,N-dimethyl phosphoramidocyanidate) is one of the highly toxic organophosphorus compounds misused as chemical warfare agents for military as well as terroristic purposes. It differs from other highly toxic organophosphates in its chemical structure and by the fact that the commonly used antidotes (atropine in combination with an oxime) are not able to sufficiently eliminate its acute toxic effects. The neuroprotective effects of the newly developed oximes (K027, K048) or trimedoxime in combination with atropine (atropine, K027/atropine, K048/atropine and trimedoxime/atropine mixtures) on rats poisoned with tabun at a lethal dose (270 mg/kg i.m.; 120% of LD50 value) were studied. The tabun-induced neurotoxicity was monitored using a functional observational battery and an automaticmeasurement of motor activity. The neurotoxicity of tabun was monitored at 24 hours and 7 days following tabun challenge. The results indicate that atropine alone is not able to protect rats from the lethal effects of tabun. Five non-treated tabun-poisoned rats and five tabun-poisoned rat treated with atropine alone died within 24 hours. On the other hand, atropine combined with all tested oximes allows most tabun-poisoned rats to survive within 7 days following tabun challenge. All three oximes tested combined with atropine seem to be sufficiently effective antidotes for a decrease in tabun-induced neurotoxicity in the case of lethal poisonings, although they are not able to eliminate tabun-induced neurotoxicity completely. Due to their neuroprotective effects, all the tested oximes appear to be more suitable oximes for the antidotal treatment of acute tabun exposure than the currently used oximes (pralidoxime, obidoxime, HI-6).

• MeSH
• atropin aplikace a dávkování   metabolismus   terapeutické užití   MeSH
• biologické markery MeSH
• experimenty na zvířatech MeSH
• financování vládou MeSH
• interpretace statistických dat MeSH
• krysa rodu rattus metabolismus   MeSH
• neuroprotektivní látky aplikace a dávkování   metabolismus   terapeutické užití   MeSH
• neurotoxiny aplikace a dávkování   farmakologie   toxicita   MeSH
• organofosfáty škodlivé účinky   MeSH
• otrava organofosfáty MeSH
• oximy aplikace a dávkování   metabolismus   terapeutické užití   MeSH
• trimedoxim aplikace a dávkování   metabolismus   terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus metabolismus   MeSH
• zvířata MeSH

The ability of two newly developed bispyridinium oximes (K456, K458) to reduce tabun-induced acute neurotoxic signs and symptoms was compared with oxime K203 and trimedoxime using the functional observational battery. The neuroprotective effects of the oximes studied combined with atropine on rats poisoned with tabun at a sublethal dose (200 μg/kg i.m.; 85% of LD50 value) were evaluated. Tabun-induced neurotoxicity was monitored by the functional observational battery and automatic measurement of motor activity at 2 hr after tabun challenge. The results indicate that all tested oximes combined with atropine enable tabun-poisoned rats to survive till the end of experiment. Both newly developed oximes (K456, K458) combined with atropine were able to decrease tabun-induced neurotoxicity in the case of sublethal poisonings although they did not eliminate all tabun-induced acute neurotoxic signs and symptoms. Their ability to decrease tabun-induced acute neurotoxicity was slightly higher than that of trimedoxime and oxime K203, but the difference in neuroprotective efficacy among all oximes studied is not large enough to make a decision about replacement of commonly used oximes (especially trimedoxime and obidoxime) in the treatment of acute tabun poisonings.

• MeSH
• atropin farmakologie   MeSH
• chemické bojové látky toxicita   MeSH
• krysa rodu rattus MeSH
• neuroprotektivní látky farmakologie   MeSH
• neurotoxické syndromy prevence a kontrola   MeSH
• organofosfáty toxicita   MeSH
• oximy farmakologie   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny farmakologie   MeSH
• trimedoxim farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

The reactivating and therapeutic efficacy of two newly developed oximes (K305, K307) was compared with the oxime K203 and trimedoxime using in vivo methods The study determining percentage of reactivation of tabun-inhibited acetylcholinesterase in the peripheral as well as central nervous system (diaphragm, brain) in tabun-poisoned rats showed that the reactivating efficacy of both newly developed oximes is lower compared to the reactivating efficacy of the oxime K203 and trimedoxime. The therapeutic efficacy of all oximes studied roughly corresponds to their reactivating efficacy. While the ability of the oxime K305 to reduce acute toxicity of tabun in mice is approaching to the therapeutic efficacy of trimedoxime, the ability of another novel bispyridinium oxime K307 to reduce acute toxicity of tabun is significantly lower compared to trimedoxime and the oxime K203. Thus, the reactivating and therapeutic efficacy of both examined newly developed oximes does not prevail the effectiveness of the oxime K203 and trimedoxime and, therefore, they are not suitable for their replacement of commonly used oximes for the treatment of acute tabun poisoning.

• MeSH
• acetylcholinesterasa účinky léků   MeSH
• antidota aplikace a dávkování   farmakologie   toxicita   MeSH
• atropin aplikace a dávkování   farmakologie   toxicita   MeSH
• bránice enzymologie   MeSH
• modely u zvířat MeSH
• mozek enzymologie   účinky léků   MeSH
• mutantní kmeny myší MeSH
• nervová bojová látka farmakologie   chemie   toxicita   MeSH
• organofosfáty farmakologie   toxicita   MeSH
• oximy * farmakologie   chemie   klasifikace   MeSH
• potkani Wistar MeSH
• reaktivátory cholinesterázy aplikace a dávkování   farmakologie   toxicita   MeSH
• trimedoxim farmakologie   chemie   klasifikace   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH

OBJECTIVE: The present experiment is based on biochemical assessment of nerve agent soman intoxication and atropine, respectively atropine and HI-6, trimedoxime or K203 treatment in rats. BACKGROUND: Nerve agents are toxic substances irreversibly inhibiting enzyme acetylcholinesterase (AChE). Treatment is typically based on application of atropine and oxime reactivator. Atropine is able to protect overstimulation of muscarinic acetylcholine receptors. Application of oxime reactivator enable return of AChE activity and full suppression of intoxication. METHODS: In a total, fifteen biochemical markers were assayed in plasma or blood of intoxicated animals. 42 rats were divided into 7 groups each 6 individuals. The first group was exposed to atropine; the second group was exposed to one LD50 of soman and atropine. The groups 3-5 were exposed in a same way as the second group and were treated with oxime reactivators: HI-6 (group 3), trimedoxime (4) and K203 (5). The sixth group was control treated with saline solution only. The last (seventh) group was intoxicated with soman only. RESULTS: The most striking shifts were found for blood acetylcholinesterase and plasma creatinine, glucose, inorganic phosphate as well as uric acid. Lactate dehydrogenase and aspartate aminotransferase assays were useless due to soman interference. CONCLUSION: It was demonstrated that treatment was able to protect poisoned animals from metabolic disorder represented by hyperglycemia and nephropathy represented by hyperuricemia and elevated creatinine. Soman exposure and treatment with the oxime reactivators and/or atropine contains quite complex and still not well understood side mechanisms (Tab. 2, Fig. 1, Ref. 25).

• MeSH
• antidota terapeutické užití   MeSH
• atropin terapeutické užití   MeSH
• biologické markery krev   MeSH
• chemické bojové látky otrava   MeSH
• cholinesterasové inhibitory otrava   MeSH
• krysa rodu rattus MeSH
• oximy terapeutické užití   MeSH
• potkani Wistar MeSH
• pyridinové sloučeniny terapeutické užití   MeSH
• reaktivátory cholinesterázy terapeutické užití   MeSH
• soman otrava   MeSH
• trimedoxim terapeutické užití   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH