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N-methyl-D-aspartate receptors (NMDARs) play a significant role in developing several central nervous system (CNS) disorders. Currently, memantine, used for treating Alzheimer's disease, and ketamine, known for its anesthetic and antidepressant properties, are two clinically used NMDAR open-channel blockers. However, despite extensive research into NMDAR modulators, many have shown either harmful side effects or inadequate effectiveness. For instance, dizocilpine (MK-801) is recognized for its powerful psychomimetic effects due to its high-affinity and nearly irreversible inhibition of the GluN1/GluN2 NMDAR subtypes. Unlike ketamine, memantine and MK-801 also act through a unique, low-affinity "membrane-to-channel inhibition" (MCI). We aimed to develop an open-channel blocker based on MK-801 with distinct inhibitory characteristics from memantine and MK-801. Our novel compound, K2060, demonstrated effective voltage-dependent inhibition in the micromolar range at key NMDAR subtypes, GluN1/GluN2A and GluN1/GluN2B, even in the presence of Mg2+. K2060 showed reversible inhibitory dynamics and a partially trapping open-channel blocking mechanism with a significantly stronger MCI than memantine. Using hippocampal slices, 30⯵M K2060 inhibited excitatory postsynaptic currents in CA1 hippocampal neurons by â¼51â¯%, outperforming 30⯵M memantine (â¼21â¯% inhibition). K2060 exhibited No Observed Adverse Effect Level (NOAEL) of 15â¯mg/kg upon intraperitoneal administration in mice. Administering K2060 at a 10â¯mg/kg dosage resulted in brain concentrations of approximately 2⯵M, with peak concentrations (Tmax) achieved within 15â¯minutes. Finally, applying K2060 with trimedoxime and atropine in mice exposed to tabun improved treatment outcomes. These results underscore K2060's potential as a therapeutic agent for CNS disorders linked to NMDAR dysfunction.
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A-series agent A-234 belongs to a new generation of nerve agents. The poisoning of a former Russian spy Sergei Skripal and his daughter in Salisbury, England, in March 2018 led to the inclusion of A-234 and other A-series agents into the Chemical Weapons Convention. Even though five years have already passed, there is still very little information on its chemical properties, biological activities, and treatment options with established antidotes. In this article, we first assessed A-234 stability in neutral pH for subsequent experiments. Then, we determined its inhibitory potential towards human recombinant acetylcholinesterase (HssAChE; EC 3.1.1.7) and butyrylcholinesterase (HssBChE; EC 3.1.1.8), the ability of HI-6, obidoxime, pralidoxime, methoxime, and trimedoxime to reactivate inhibited cholinesterases (ChEs), its toxicity in rats and therapeutic effects of different antidotal approaches. Finally, we utilized molecular dynamics to explain our findings. The results of spontaneous A-234 hydrolysis showed a slow process with a reaction rate displaying a triphasic course during the first 72 h (the residual concentration 86.2%). A-234 was found to be a potent inhibitor of both human ChEs (HssAChE IC50 = 0.101 ± 0.003 µM and HssBChE IC50 = 0.036 ± 0.002 µM), whereas the five marketed oximes have negligible reactivation ability toward A-234-inhibited HssAChE and HssBChE. The acute toxicity of A-234 is comparable to that of VX and in the context of therapy, atropine and diazepam effectively mitigate A-234 lethality. Even though oxime administration may induce minor improvements, selected oximes (HI-6 and methoxime) do not reactivate ChEs in vivo. Molecular dynamics implies that all marketed oximes are weak nucleophiles, which may explain the failure to reactivate the A-234 phosphorus-serine oxygen bond characterized by low partial charge, in particular, HI-6 and trimedoxime oxime oxygen may not be able to effectively approach the A-234 phosphorus, while pralidoxime displayed low interaction energy. This study is the first to provide essential experimental preclinical data on the A-234 compound.
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Reactivadores de la Colinesterasa , Compuestos de Pralidoxima , Taurina/análogos & derivados , Ratas , Humanos , Animales , Reactivadores de la Colinesterasa/farmacología , Trimedoxima/farmacología , Butirilcolinesterasa , Acetilcolinesterasa , Oximas/farmacología , Compuestos de Piridinio/farmacología , Antídotos/farmacología , Inhibidores de la Colinesterasa/toxicidad , Fósforo , OxígenoRESUMEN
BACKGROUND: There is no single gold standard for investigation of gastrointestinal motility function. Wireless motility monitoring involves a novel concept which provides a complex information on gastrointestinal function (gastrointestinal transit time, intra-luminal pH, pressure and temperature). Gastrointestinal motility functions of experimental pigs are very similar to those of humans. That is why porcine studies have already provided suitable experimental models for several preclinical projects. AIMS: The aim of our study was to adopt methods of non-invasive wireless monitoring of gastrointestinal functions in experimental pigs. METHODS: Five experimental adult female pigs were enrolled into the study. Wireless motility capsules were delivered into the porcine stomach endoscopically. Gastrointestinal transit and intra-luminal conditions were recorded for five days. RESULTS: Records of animals provided good (3 pigs) or very good quality files (2 pigs). 31150 variables were evaluated. Mean time of the presence of capsules in the stomach was 926 ± 295 min, transfer of a capsule from the stomach into the duodenum lasted 5-34 min. Mean small intestinal transit time was 251 ± 43 min. Food intake was associated with an increase of gastric luminal temperature and a decrease of intra-gastric pressure. The highest intra-luminal pH was present in the ileum. The highest temperature and the lowest intra-luminal pressure were found in the colon. All data displayed a substantial inter-individual variability. CONCLUSIONS: This pilot study has proven that a long-term function monitoring of the gastrointestinal tract by means of wireless motility capsules in experimental pigs is feasible. However, both ketamine-based induction of general anaesthesia as well as long-lasting general anaesthesia (> 6 hours) should be avoided to prevent retention of a capsule in the porcine stomach.
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Tránsito Gastrointestinal , Adulto , Humanos , Femenino , Animales , Porcinos , Temperatura , Proyectos Piloto , Cápsulas , Concentración de Iones de HidrógenoRESUMEN
BACKGROUND: Rivastigmine is a pseudo-irreversible cholinesterase inhibitor used for therapy of Alzheimer's disease and non-Alzheimer dementia syndromes. In humans, rivastigmine can cause significant gastrointestinal side effects that can limit its clinical use. The aim of this study was to assess the impact of rivastigmine on gastric motor function by means of electrogastrography (EGG) in experimental pigs. METHODS: Six experimental adult female pigs (Sus scrofa f. domestica, hybrids of Czech White and Landrace breeds; 3-month-old; mean weight 30.7 ± 1.2 kg) were enrolled into the study twice and created two experimental groups. In group A, a single intragastric dose of 6 mg rivastigmine hydrogen tartate was administered in the morning to fasting pigs before EGG recording. In group B, rivastigmine was administered to overnight fasting animals in a dietary bolus in the morning for 7 days (6 mg per day). On day 8, an intragastric dose of 12 mg rivastigmine was given in the morning to fasting pigs before EGG. EGG recording was accomplished by means of an EGG standalone system. Recordings from both groups were evaluated in dominant frequency and EGG power (areas of amplitudes). RESULTS: In total, 1,980 one-minute EGG intervals were evaluated. In group A, basal EGG power (median 1290.5; interquartile range 736.5-2330 µV2) was significantly higher in comparison with the power of intervals T6 (882; 577-1375; p = 0.001) and T10 (992.5; 385-2859; p = 0.032). In group B, the dominant frequency increased significantly from basal values (1.97 ± 1.57 cycles per minute) to intervals T9 (3.26 ± 2.16; p < 0.001) and T10 (2.14 ± 1.16; p = 0.012), respectively. In group B, basal EGG power (median 1030.5; interquartile range 549-5093) was significantly higher in comparison with the power of intervals T7 (692.5; 434-1476; p = 0.002) and T8 (799; 435-1463 µV2; p = 0.004). CONCLUSIONS: Both single as well as repeated intragastric administration of rivastigmine hydrogen tartrate caused a significant decrease of EGG power (areas of amplitudes) in experimental pigs. EGG power may serve as an indirect indicator of gastric motor competence. These findings might provide a possible explanation of rivastigmine-associated dyspepsia in humans.
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Enfermedad de Alzheimer , Estómago , Humanos , Animales , Femenino , Lactante , Rivastigmina/farmacología , Tracto Gastrointestinal , Electromiografía , Inhibidores de la Colinesterasa/farmacología , Fenilcarbamatos/farmacologíaRESUMEN
Organophosphorus nerve agents pose a global threat to both military personnel and civilian population, because of their high acute toxicity and insufficient medical countermeasures. Commonly used drugs could ameliorate the intoxication and overall medical outcomes. In this study, we tested the drugs able to alleviate the symptoms of Alzheimer's disease (donepezil, huperzine A, memantine) or Parkinson's disease (procyclidine). They were administered to mice before soman intoxication in terms of their: i) protection potential against soman toxicity and ii) influence on post-exposure therapy consisting of atropine and asoxime (also known as oxime HI-6). Their pretreatment effect was not significant, when administered alone, but in combination (acetylcholinesterase inhibitor such as denepezil or huperzine A with NMDA antagonist such as memantine or procyclidine) they lowered the soman toxicity more than twice. These combinations also positively influenced the efficacy of post-exposure treatment in a similar fashion; the combinations increased the therapeutic effectiveness of antidotal treatment. In conclusion, the most effective combination - huperzine A and procyclidine - lowered the toxicity three times and improved the post-exposure therapy efficacy more than six times. These results are unprecedented in the published literature.
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Venenos , Soman , Ratones , Animales , Inhibidores de la Colinesterasa/toxicidad , Soman/toxicidad , Acetilcolinesterasa/metabolismo , Receptores de N-Metil-D-Aspartato , Prociclidina/farmacología , Memantina/uso terapéutico , Tasa de Supervivencia , Compuestos de Piridinio/farmacología , Antídotos/uso terapéutico , Atropina/uso terapéutico , Atropina/farmacología , Oximas/uso terapéutico , Oximas/farmacologíaRESUMEN
Oxime reactivators are causal antidotes for organophosphate intoxication. Herein, the toxicity, pharmacokinetics, and reactivation effectiveness of o-chlorinated bispyridinium oxime K870 are reported. Oxime K870 was found to have a safe profile at a dose of 30 mg/kg in rats. It exhibited rapid absorption and renal clearance similar to those of other charged oximes after intramuscular administration. Its isoxazole-pyridinium degradation product was identified in vivo. Although it showed some improvement in brain targeting, it was nevertheless rapidly effluxed from the central nervous system. Its reactivation effectiveness was evaluated in rats and mice intoxicated with sarin, tabun, VX, and paraoxon and compared with pralidoxime and asoxime. K870 was found to be less effective in reversing tabun poisoning compared to its parent unchlorinated oxime K203. However, K870 efficiently reactivated blood acetylcholinesterase for all tested organophosphates in rats. In addition, K870 significantly protected against intoxication by all tested organophosphates in mice. For these reasons, oxime K870 seems to have a broader reactivation spectrum against multiple organophosphates. It seems important to properly modulate the oximate forming properties (pKa) to obtain more versatile oxime reactivators.
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Reactivadores de la Colinesterasa , Oximas , Acetilcolinesterasa/metabolismo , Animales , Antídotos , Inhibidores de la Colinesterasa/metabolismo , Inhibidores de la Colinesterasa/toxicidad , Reactivadores de la Colinesterasa/uso terapéutico , Ratones , Organofosfatos , Compuestos de Piridinio/toxicidad , RatasRESUMEN
Cucurbit[n]urils are macrocyclic compounds capable of forming host-guest complexes with different molecules. In this study, we focused on cucurbit[7]uril (CB[7]) safety and pharmacokinetics. We investigated CB[7] cytotocixity in human renal cells ACHN using the xCELLigence system. We also determined maximum tolerated doses (MTD) and no observed adverse effect levels (NOAEL) after intramuscular (i.m.), intraperitoneal (i.p.), and intragastric (i.g.) administration in mice using clinical observation, blood biochemistry, and histopathology. At NOAELs, we studied its pharmacokinetics in plasma and kidneys. Finally, we performed a 7 day repeated-dose toxicity study at 50% of NOAEL after i.p. administration, assaying CB[7] concentration in plasma, brain, kidney, and liver; we also assessed the liver and kidney histopathology. In vitro, CB[7] did not show toxicity up to 0.94 mg/mL. MTDs in vivo were set at 300, 350, and 600 mg/kg, and NOAEL were established at 150, 100, and 300 mg/kg after i.m., i.p., and i.g. administration, respectively. Parenteral administration produced tissue damage mainly to the kidney, while i.g. administration caused only minor liver damage. Parenteral CB[7] administration led to fast elimination from blood, accompanied with kidney accumulation; absorption from the gastrointestinal tract was minimal. Short repeated i.p. administration was well tolerated. After initial CB[7] accumulation in blood and kidney, the concentrations stabilised and decreased during the experiment. Approximately 3.6% of animals showed signs of nephrotoxicity. Although CB[7] appears to be a promising molecule, nephrotoxicity may be the most critical drawback of its parenteral use, because the kidney represents the main organ of its elimination.
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Compuestos Heterocíclicos con 2 Anillos , Imidazolidinas , Compuestos Macrocíclicos , Animales , Compuestos Heterocíclicos con 2 Anillos/toxicidad , Imidazolidinas/toxicidad , Compuestos Macrocíclicos/toxicidad , Dosis Máxima Tolerada , RatonesRESUMEN
AIM: The comparison of neuroprotective and central reactivating effects of the oxime K870 in combination with atropine with the efficacy of standard antidotal treatment in tabun-poisoned rats. METHODS: The neuroprotective effects of antidotal treatment were determined in rats poisoned with tabun at a sublethal dose using a functional observational battery 2 h and 24 h after tabun administration, the tabun-induced brain damage was investigated by the histopathological evaluation and central reactivating effects of oximes was evaluated by the determination of acetylcholinesterase activity in the brain using a standard spectrophotometric method. RESULTS: The central reactivating efficacy of a newly developed oxime K870 roughly corresponds to the central reactivating efficacy of pralidoxime while the ability of the oxime HI-6 to reactivate tabun-inhibited acetylcholinesterase in the brain was negligible. The ability of the oxime K870 to decrease tabun-induced acute neurotoxicity was slightly higher than that of pralidoxime and similar to the oxime HI-6. These results roughly correspond to the histopathological evaluation of tabun-induced brain damage. CONCLUSION: The newly synthesized oxime K870 is not a suitable replacement for commonly used oximes in the antidotal treatment of acute tabun poisonings because its neuroprotective efficacy is only slightly higher or similar compared to studied currently used oximes.
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Sustancias para la Guerra Química , Reactivadores de la Colinesterasa , Organofosfatos , Oximas , Venenos , Compuestos de Piridinio , Acetilcolinesterasa , Animales , Antídotos/farmacología , Sustancias para la Guerra Química/toxicidad , Inhibidores de la Colinesterasa/farmacología , Reactivadores de la Colinesterasa/farmacología , Oximas/farmacología , Compuestos de Pralidoxima , Compuestos de Piridinio/farmacología , Ratas , Ratas WistarRESUMEN
Galantamine has been used as a treatment for Alzheimer disease. It has a unique, dual mode of action (inhibitor of acetylcholinesterase and allosteric modulator of nicotinic acetylcholine receptors). Nausea (in about 20%), vomiting (10%) and diarrhoea (5-7%) are the most common side effects. The aim of this study was to assess the effect of galantamine on porcine gastric myoelectric activity without (Group A) and with (Group B) dextran sodium sulphate (DSS)-induced gastrointestinal injury. Galantamine hydrobromide was administrated to twelve pigs as a single intragastric dose (24 mg). Gastric myoelectric activity was investigated by electrogastrography (EGG). Basal (15 min before galantamine administration) and study recordings after galantamine administration (300 min) were evaluated using a running spectral analysis. Results were expressed as dominant frequency of gastric slow waves and power analysis (areas of amplitudes). Altogether, 3780 one-minute EGG recordings were evaluated. In Group A, power was steady from basal values for 180 min, then gradually decreased till 270 min (p = 0.007). In Group B, there was a rapid gradual fall from basal values to those after 120 min (p = 0.007) till 300 min (p Ë 0.001). In conclusion, galantamine alone revealed an unfavourable effect on porcine myoelectric activity assessed by gastric power. It can be a plausible explanation of galantamine-associated dyspepsia in humans. DSS caused further profound decrease of EGG power. That may indicate that underlying inflammatory, ischaemic or NSAIDs-induced condition of the intestine in humans can have aggravated the effect of galantamine on gastric myoelectric activity.
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3-Quinuclidinyl benzilate (BZ) ranks among incapacitating military warfare agents. It acts as a competitive inhibitor on muscarinic receptors leading to non-lethal mental impairment. The present study aimed to investigate toxicokinetics of BZ in rats. Moreover, BZ can be exploited to produce a pharmacological model of Alzheimer's disease; thus, this paper focuses mainly on the BZ distribution to the brain. Wistar rats were administered i.p. with BZ (2 and 10 mg/kg). The BZ concentration was determined using LC-MS/MS in plasma, urine, bile, brain, kidney and liver. The sample preparation was based on a solid phase extraction (liquids) or protein precipitation (organ homogenates). The plasma concentration peaked at 3 min (204.5 ± 55.4 and 2185.5 ± 465.4 ng/ml). The maximal concentration in the brain was reached several minutes later. Plasma elimination half-life was 67.9 ± 3.4 in the 2 mg/kg group and 96.6 ± 27.9 in the 10 mg/kg group. BZ concentrations remained steady in the brain, with slow elimination (t1/2 506.9 ± 359.5 min). Agent BZ is excreted mainly via the urine. Steady BZ concentration in the brain could explain the previously published duration of the significant impairment in passive avoidance tasks in rats after an injection of BZ.
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Antagonistas Muscarínicos/metabolismo , Antagonistas Muscarínicos/toxicidad , Quinuclidinil Bencilato/metabolismo , Quinuclidinil Bencilato/toxicidad , Animales , Bilis/metabolismo , Encéfalo/metabolismo , Masculino , Metaboloma , Antagonistas Muscarínicos/sangre , Antagonistas Muscarínicos/orina , Quinuclidinil Bencilato/sangre , Quinuclidinil Bencilato/orina , Ratas , Ratas Wistar , Toxicocinética , OrinaRESUMEN
Gastrointestinal side effects of donepezil, including dyspepsia, nausea, vomiting or diarrhea, occur in 20-30% of patients. The pathogenesis of these dysmotility associated disorders has not been fully clarified yet. Pharmacokinetic parameters of donepezil and its active metabolite 6-O-desmethyldonepezil were investigated in experimental pigs with and without small intestinal injury induced by dextran sodium sulfate (DSS). Morphological features of this injury were evaluated by a video capsule endoscopy. The effect of a single and repeated doses of donepezil on gastric myoelectric activity was assessed. Both DSS-induced small intestinal injury and prolonged small intestinal transit time caused higher plasma concentrations of donepezil in experimental pigs. This has an important implication for clinical practice in humans, with a need to reduce doses of the drug if an underlying gastrointestinal disease is present. Donepezil had an undesirable impact on porcine myoelectric activity. This effect was further aggravated by DSS-induced small intestinal injury. These findings can explain donepezil-associated dyspepsia in humans.
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Donepezilo/farmacocinética , Tracto Gastrointestinal/patología , Tracto Gastrointestinal/fisiopatología , Indanos/metabolismo , Metaboloma , Complejo Mioeléctrico Migratorio , Piperidinas/metabolismo , Estómago/fisiopatología , Animales , Endoscopía Capsular , Sulfato de Dextran , Donepezilo/química , Donepezilo/farmacología , Femenino , Tracto Gastrointestinal/efectos de los fármacos , Metaboloma/efectos de los fármacos , Complejo Mioeléctrico Migratorio/efectos de los fármacos , Estómago/efectos de los fármacos , PorcinosRESUMEN
The search for tacrine derivatives, as potential Alzheimer´s disease treatment, is still being at the forefront of scientific efforts. 7-MEOTA was found to be a potent, centrally active acetylcholinesterase inhibitor free of the serious side effects observed for tacrine. Unfortunately, a relevant argumentation about pharmacokinetics and potential toxicity is incomplete; information about tacrine derivatives absorption and especially CNS penetration are still rare as well as detailed toxicological profile in vivo. Although the structural changes between these compounds are not so distinctive, differences in plasma profile and CNS targeting were found. The maximum plasma concentration were attained at 18th min (tacrine; 38.20 ± 3.91 ng/ml and 7-MEOTA; 88.22 ± 15.19 ng/ml) after i.m. application in rats. Although the brain profiles seem to be similar; tacrine achieved 19.34 ± 0.71 ng/ml in 27 min and 7-MEOTA 15.80 ± 1.13 ng/ml in 22 min; the tacrine Kp (AUCbrain/AUCplasma) fit 1.20 and was significantly higher than 7-MEOTA Kp 0.10. Administration of tacrine and 7-MEOTA showed only mild elevation of some biochemical markers following single p.o. application in 24 hours and 7 days. Also histopathology revealed only mild-to-moderate changes following repeated p.o. administration for 14 days. It seems that small change in tacrine molecule leads to lower ability to penetrate through the biological barriers. The explanation that lower p.o. acute toxicity of 7-MEOTA depends only on differences in metabolic pathways may be now revised to newly described differences in pharmacokinetic and toxicological profiles.
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Encéfalo/metabolismo , Inhibidores de la Colinesterasa/administración & dosificación , Tacrina/análogos & derivados , Animales , Área Bajo la Curva , Inhibidores de la Colinesterasa/farmacocinética , Inhibidores de la Colinesterasa/toxicidad , Masculino , Ratas , Ratas Wistar , Tacrina/administración & dosificación , Tacrina/farmacocinética , Tacrina/toxicidad , Factores de Tiempo , Distribución TisularRESUMEN
Antidotes against organophosphates often possess physicochemical properties that mitigate their passage across the blood-brain barrier. Cucurbit[7]urils may be successfully used as a drug delivery system for bisquaternary oximes and improve central nervous system targeting. The main aim of these studies was to elucidate the relationship between cucurbit[7]uril, oxime K027, atropine, and paraoxon to define potential risks or advantages of this delivery system in a complex in vivo system. For this reason, in silico (molecular docking combined with umbrella sampling simulation) and in vivo (UHPLC-pharmacokinetics, toxicokinetics; acetylcholinesterase reactivation and functional observatory battery) methods were used. Based on our results, cucurbit[7]urils affect multiple factors in organophosphates poisoning and its therapy by (i) scavenging paraoxon and preventing free fraction of this toxin from entering the brain, (ii) enhancing the availability of atropine in the central nervous system and by (iii) increasing oxime passage into the brain. In conclusion, using cucurbit[7]urils with oximes might positively impact the overall treatment effectiveness and the benefits can outweigh the potential risks.
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Atropina/química , Hidrocarburos Aromáticos con Puentes/química , Imidazoles/química , Oximas/química , Paraoxon/toxicidad , Compuestos de Piridinio/química , Animales , Barrera Hematoencefálica , Reactivadores de la Colinesterasa/química , Reactivadores de la Colinesterasa/toxicidad , Simulación por Computador , Ratones , Simulación del Acoplamiento Molecular , Paraoxon/químicaRESUMEN
Oxime-based acetylcholinesterase reactivators (briefly oximes) regenerate organophosphate-inactivated acetylcholinesterase and restore its function. Poor blood-brain-barrier passage and fast elimination from blood limit their actual use in treatment of patients exposed to organophosphates. Previous in vitro results implicated further testing of cucurbit[7]uril as a delivery vehicle for bisquaternary oximes. The present paper focuses on cell toxicity, in vivo safety and influence of cucurbit[7]uril on oxime pharmacokinetics and pharmacodynamics. Neither the K027 nor the complex caused any cell toxicity, changes in blood biochemistry or hepato- or nephrotoxicity in tested concentrations. The encapsulation of K027 increased and accelerated the blood-brain-barrier penetration. The peripheral oxime exposure also increased, supporting the suggestion that cucurbit[7]uril protects the circulating oxime from rapid renal clearance. Contrary to the comparable in vitro reactivation power of K027 and the encapsulated K027, we failed to confirm this in vivo. In theory, this might result from the non-specific binding of molecules to the cucurbit[7]uril or the interaction of K027 with cucurbit[7]uril being too strong for acetylcholinesterase reactivation. Precise explanation requires additional in silico, in vitro and also in vivo experiments.
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Acetilcolinesterasa/sangre , Acetilcolinesterasa/metabolismo , Encéfalo/efectos de los fármacos , Hidrocarburos Aromáticos con Puentes/farmacocinética , Reactivadores de la Colinesterasa/farmacocinética , Eritrocitos/efectos de los fármacos , Imidazoles/farmacocinética , Oximas/farmacocinética , Compuestos de Piridinio/farmacocinética , Células A549 , Animales , Encéfalo/enzimología , Hidrocarburos Aromáticos con Puentes/administración & dosificación , Hidrocarburos Aromáticos con Puentes/toxicidad , Supervivencia Celular/efectos de los fármacos , Reactivadores de la Colinesterasa/administración & dosificación , Reactivadores de la Colinesterasa/toxicidad , Relación Dosis-Respuesta a Droga , Eritrocitos/enzimología , Femenino , Proteínas Ligadas a GPI/sangre , Proteínas Ligadas a GPI/metabolismo , Células Hep G2 , Humanos , Imidazoles/administración & dosificación , Imidazoles/toxicidad , Inyecciones Intramusculares , Masculino , Dosis Máxima Tolerada , Ratones Endogámicos ICR , Oximas/administración & dosificación , Oximas/toxicidad , Compuestos de Piridinio/administración & dosificación , Compuestos de Piridinio/toxicidad , Medición de Riesgo , Distribución TisularRESUMEN
Agent BZ (3-quinuclidinyl benzilate) is a centrally acting synthetic anticholinergic agent, considered as a potential military incapacitating chemical warfare agent. Despite its significance as a model compound in pharmacological research and its potential misuse in chemical attacks, few modern analytical methods for BZ determination in biological samples have been published. The goal of the present work is to develop and validate a sensitive and rapid LC-MS/MS method for the determination of agent BZ in rat plasma. The sample preparation was based on solid-phase extraction on C-18 cartridges. The reversed-phase HPLC coupled with the mass spectrometer with electrospray ionization in the positive ion-selective reaction monitoring mode was employed in the BZ analysis. Atropine was used as an internal standard. The presented method is selective, accurate, precise, and linear (r2 = 0.9947) in a concentration range from 0.5 ng/mL to 1 000 ng/mL and sensitive enough (limit of detection 0.2 ng/mL; limit of quantification 0.5 ng/mL) to determine the BZ plasma levels in rats exposed to 2 mg/kg and 10 mg/kg of BZ. The highest level of BZ in plasma was observed 5 minutes after intramuscular administration (154.6 ± 22.3 ng/mL in rats exposed to 2 mg/kg of BZ and 1024 ± 269 ng/mL in rats exposed to 10 mg/kg). After 48 h, no BZ was observed at detectable levels. This new method allows the detection and quantification of BZ in biological samples after exposure of an observed organism and it will be further optimized for other tissues to observe the distribution of BZ in organs.
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Antagonistas Colinérgicos/sangre , Quinuclidinil Bencilato/sangre , Animales , Antagonistas Colinérgicos/análisis , Cromatografía Líquida de Alta Presión , Límite de Detección , Masculino , Quinuclidinil Bencilato/análisis , Ratas , Ratas Wistar , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masas en TándemRESUMEN
Memantine is a noncompetitive N-methyl-d-aspartate (NMDA) receptor antagonist utilized as a palliative cure for Alzheimer's disease. This is the second study examining the memantine concentrations in cerebrospinal fluid. The previously published study enrolled six patients, and three of them were theoretically in a steady state. In our study, we enrolled 22 patients who regularly used a standard therapeutic dose of memantine (20 mg/day, oral administration) before the sample collection. Patients were divided into four groups, according to the time of plasma and cerebrospinal fluid collection: 6, 12, 18, and 24 h after memantine administration. The cerebrospinal fluid samples were also assessed for selected oxidative stress parameters (malondialdehyde, 3-nitrotyrosine, glutathione, non-protein thiols, and non-protein disulfides). The plasma/cerebrospinal fluid (CSF) ratio for all time intervals were within the range of 45.89% (6 h) to 55.60% (18 h), which corresponds with previously published findings in most patients. The other aim of our study was to deduce whether the achieved "real" memantine concentration in the central compartment was sufficient to block NMDA receptors. The IC50 value of memantine as an NMDA antagonist is in micromolar range; the lowest limit is 112 ng/ml (GluN2C), and this value was achieved only in three cases. The memantine cerebrospinal fluid concentration did not reach one quarter of the IC50 value in five cases (one patient was excluded for noncompliance); therefore, the potency of memantine as a therapeutic effect in patients may be questionable. However, it appears that memantine therapy positively affected the levels of some oxidative stress parameters, especially non-protein thiols and 3-nitrotyrosine.
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A combination of tacrine and tryptophan led to the development of a new family of heterodimers as multi-target agents with potential to treat Alzheimer's disease. Based on the in vitro biological profile, compound S-K1035 was found to be the most potent inhibitor of human acetylcholinesterase (hAChE) and human butyrylcholinesterase (hBChE), demonstrating balanced IC50 values of 6.3 and 9.1â¯nM, respectively. For all the tacrine-tryptophan heterodimers, favorable inhibitory effect on hAChE as well as on hBChE was coined to the optimal spacer length ranging from five to eight carbon atoms between these two pharmacophores. S-K1035 also showed good ability to inhibit Aß42 self-aggregation (58.6⯱â¯5.1% at 50⯵M) as well as hAChE-induced Aß40 aggregation (48.3⯱â¯6.3% at 100⯵M). The X-ray crystallographic analysis of TcAChE in complex with S-K1035 pinpointed the utility of the hybridization strategy applied and the structures determined with the two K1035 enantiomers in complex with hBChE could explain the higher inhibition potency of S-K1035. Other in vitro evaluations predicted the ability of S-K1035 to cross blood-brain barrier and to exert a moderate inhibition potency against neuronal nitric oxide synthase. Based on the initial promising biochemical data and a safer in vivo toxicity compared to tacrine, S-K1035 was administered to scopolamine-treated rats being able to dose-dependently revert amnesia.
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Enfermedad de Alzheimer/tratamiento farmacológico , Inhibidores de la Colinesterasa/farmacología , Fármacos Neuroprotectores/farmacología , Tacrina/farmacología , Triptófano/farmacología , Acetilcolinesterasa/metabolismo , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/antagonistas & inhibidores , Péptidos beta-Amiloides/metabolismo , Animales , Butirilcolinesterasa/metabolismo , Inhibidores de la Colinesterasa/síntesis química , Inhibidores de la Colinesterasa/química , Relación Dosis-Respuesta a Droga , Humanos , Ligandos , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Estructura Molecular , Fármacos Neuroprotectores/síntesis química , Fármacos Neuroprotectores/química , Agregado de Proteínas/efectos de los fármacos , Ratas , Ratas Wistar , Relación Estructura-Actividad , Tacrina/química , Triptófano/químicaAsunto(s)
Barrera Hematoencefálica/metabolismo , Indanos , Piperidinas , Animales , Transporte Biológico , Cromatografía Líquida de Alta Presión , Donepezilo , Indanos/sangre , Indanos/química , Indanos/farmacocinética , Modelos Lineales , Masculino , Piperidinas/sangre , Piperidinas/química , Piperidinas/farmacocinética , Ratas , Ratas Wistar , Reproducibilidad de los Resultados , Sensibilidad y EspecificidadRESUMEN
BACKGROUND: Based on in vitro and in vivo rat experiments, the newly developed acetylcholinesterase (AChE) reactivator, K203, appears to be much more effective in the treatment of tabun poisonings than currently fielded oximes. METHODS: To determine if this reactivating efficacy would extend to humans, studies were conducted in vitro using human brain homogenate as the source of AChE. The efficacy of K203 was compared with commercially available oximes; pralidoxime, obidoxime and asoxime (HI-6). RESULTS: Reactivation studies showed that K203 was the most effective reactivator with a second order kinetic constant (kr) of 2142 min- 1. M- 1, which was 51 times higher than that obtained for obidoxime (kr = 42 min- 1. M- 1). Both pralidoxime and asoxime (HI-6) failed to significantly reactivate tabun-inhibited human AChE. DISCUSSION: According to these results and previous studies, using K203, it appears that oxime K203 is the most effective reactivator of tabun-inhibited cholinesterase in several species including humans and should be considered as a possible medical countermeasure to tabun exposure.
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Acetilcolinesterasa/metabolismo , Antídotos/metabolismo , Inhibidores de la Colinesterasa/metabolismo , Reactivadores de la Colinesterasa/metabolismo , Organofosfatos/metabolismo , Oximas/metabolismo , Compuestos de Piridinio/metabolismo , Animales , Encéfalo/enzimología , Humanos , Simulación del Acoplamiento Molecular , RatasRESUMEN
The objective of this study was to elucidate the pharmacokinetics and metabolite formation of newly developed non-selective AChE/BChE 7-MEOTA-donepezil-like inhibitors for potential therapeutic use in Alzheimer's disease (AD) patients. The chemical structures of metabolites were defined during incubation with human liver microsomes, and subsequently, the metabolization was verified in in vivo study. In vitro metabolic profiling revealed the formation of nine major metabolites in the case of PC-37 and eight metabolites of PC-48. Hydroxylation and the enzymatic hydrolysis of bonds close to the piperazine ring appeared to be the principal metabolic pathways in vitro. Of these metabolites, M1-M7 of PC-37 and M1-M6 of PC-48 were confirmed under in vivo conditions. Pilot pharmacokinetic experiments in rats were focused on the absorption, distribution and elimination of these compounds. Absorption after i.m. application was relatively fast; the bioavailability expressed as AUCtotal was 28179 ± 4691 min.ng/mL for PC-37 and 23374 ± 4045 min.ng/mL for PC-48. Both compounds showed ability to target the central nervous system, with brain concentrations exceeding those in plasma. The maximal brain concentrations are approximately two times higher than the plasma concentrations. The relatively high brain concentrations persisted throughout the experiment until 24 hr after application. Elimination via the kidneys (urine) significantly exceeded elimination via the liver (bile). All these characteristics are crucial for new candidates intended for AD treatment. The principle metabolic pathways that were verified in the in vivo study do not show any evidence for formation of extremely toxic metabolites, but this needs to be confirmed by further studies.