Clinical utility of validated gas chromatography-ion trap mass spectrometry in patients with anticholinesterase pesticides poisoning.

Intentional or unintentional intake of anticholinesterase pesticides became common due to their extensive use in agricultural and domestic purposes, resulting in numerous poisoning cases. A simple, accurate, and sensitive gas chromatography-ion trap mass spectrometry-based method for the quantification of 12 anticholinesterase pesticides (monocrotophos, dimethoate, dichlorvos, azinphos-methyl, carbofuran, chlorpyrifos, dialifos, diazinon, malathion, parathion, methidathion, and terbufos) in serum was developed, and its utility in patients with alleged pesticides poisoning was assessed. The quantification was performed using liquid-liquid extraction by toluene/chloroform (4:1,v/v) with 500 µL of serum. On column limit of detection and limit of quantification were less than 50.00 µg/L. The recovery ranged from 97.54 to 103.23%. The calibration curves were linear (R2 > 0.9937). Accuracy was found to be between - 7.1 and 7.2%. Intra-day and inter-day reproducibility was less than 17% for the spiked quality control serum samples. The level of pesticide in serum quantified by the validated method correlated with clinical signs and symptoms, pseudo-cholinesterase activity, total atropine dose, length of hospital stay, and clinical outcome in 15 patients with alleged pesticide poisoning. The validated method may be used for monitoring and prognosis in patients with pesticide poisoning and diagnosis of poisoning in forensic toxicology.

Análise do impacto do uso de organofosforados e carbamatos em trabalhadores rurais de um município da região noroeste do estado do Rio Grande do Sul / Impact analysis of the use of organophosphates and carbamates rural workers of the municipality in a northwest region of Rio Grande do Sul

Anualmente milhões de agricultores são intoxicados no mundo, e destes, mais de 20 mil morrem em consequência da exposição a agrotóxicos. Intoxicações por organofosforados (OF) e carbamatos (CAR) representam as maiores ameaças à saúde dos trabalhadores rurais. Os OF e CAR atuam na inibição da enzima colinesterase, sendo assim a inibição desta mostra-se um excelente indicador da severidade da intoxicação. O objetivo deste estudo foi analisar o impacto do uso de OF e CAR em trabalhadores rurais na cidade de Mato Queimado/RS. Foi realizado um estudo transversal, prospectivo e experimental. Investigaramse 27 trabalhadores rurais expostos. Foram realizadas coletas sanguíneas e dados epidemiográficos nos meses de fevereiro e março de 2014. A atividade da colinesterase foi determinada através do método bioquímico cinético colorimétrico. A faixa etária média dos participantes foi 34,6 anos (± 8,5). A forma de contato mais prevalente foi a aplicação do produto (88,9%). O tempo médio de exposição foi de 10,7 anos. 70,4% relataram usar equipamentos de proteção individual (EPI), sendo mais frequente o uso de máscara (55,5%). A média dos valores de colinesterase para foi de 3244,45 U/I (± 345,8), níveis estes abaixo dos de referência. Através dos resultados obtidos nesta pesquisa torna-se imprescindível a utilização de meios de monitoramento biológico dos trabalhadores rurais na finalidade de prevenção e promoção da saúde.

Annually millions of rural workers are intoxicated in the world, and of these, more than 20,000 die as a result of exposure to pesticides. Intoxication by insecticides organophosphate (OF) and carbamates (CAR) represent the greatest threats to the health of rural workers. OF CAR and act on the inhibition of cholinesterase enzyme, thus inhibition of this proves to be an excellent indicator of the severity of the intoxication. The objective of this study was to analyze the impact of using OF CAR and in rural workers in the city of Mato Queimado/RS. A cross-sectional, prospective and experimental study was conducted. Twenty-three rural workers exposed were investigated. Sample collection and data demographic were conducted in February and March 2014. The cholinesterase activity was determined by biochemical kinetic colorimetric method. The average age of participants was 34.6 years (± 8.5). The most prevalent form of contact is via the application of the product (88.9%). The mean duration of exposure was 10.7 years. Still, 70.4% reported using personal protective equipment (PPE), more frequent use of mask (55.5%). The average values for cholinesterase was 3244.45 U/l (± 345.8) levels below those of the reference. The results obtained in this study are essential to use biological monitoring means of rural workers in purpose of prevention and health promotion.

C-547, a 6-methyluracil derivative with long-lasting binding and rebinding on acetylcholinesterase: Pharmacokinetic and pharmacodynamic studies.

C-547, a potent slow-binding inhibitor of acetylcholinesterase (AChE) was intravenously administered to rat (0.05 mg/kg). Pharmacokinetic profiles were determined in blood and different organs: extensor digitorum longus muscle, heart, liver, lungs and kidneys as a function of time. Pharmacokinetics (PK) was studied using non-compartmental and compartmental analyses. A 3-compartment model describes PK in blood. Most of injected C-547 binds to albumin in the bloodstream. The steady-state volume of distribution (3800 ml/kg) is 15 times larger than the distribution volume, indicating a good tissue distribution. C-547 is slowly eliminated (kel = 0.17 h-1; T1/2 = 4 h) from the bloodstream. Effect of C-547 on animal model of myasthenia gravis persists for more than 72 h, even though the drug is not analytically detectable in the blood. A PK/PD model was built to account for such a pharmacodynamical (PD) effect. Long-lasting effect results from micro-PD mechanisms: the slow-binding nature of inhibition, high affinity for AChE and long residence time on target at neuromuscular junction (NMJ). In addition, NMJ spatial constraints i.e. high concentration of AChE in a small volume, and slow diffusion rate of free C-547 out of NMJ, make possible effective rebinding of ligand. Thus, compared to other cholinesterase inhibitors used for palliative treatment of myasthenia gravis, C-547 is the most selective drug, displays a slow pharmacokinetics, and has the longest duration of action. This makes C-547 a promising drug leader for treatment of myasthenia gravis, and a template for development of other drugs against neurological diseases and for neuroprotection.

Distigmine Bromide Produces Sustained Potentiation of Guinea-Pig Urinary Bladder Motility by Inhibiting Cholinesterase Activity.

Distigmine is a cholinesterase (ChE) inhibitor used for the treatment of detrusor underactivity in Japan. Distigmine's pharmacological effects are known to be long-lasting, but the duration of its effect on urinary bladder contractile function has not been fully elucidated. The present study aimed to determine these effects in relation to the plasma concentrations of distigmine and its inhibition of ChE activities in blood, plasma, and bladder tissue. Intravesical pressures were recorded in anesthetized guinea-pigs for 12 h after the intravenous administration of saline or distigmine (0.01-0.1 mg/kg). Plasma distigmine concentrations were measured by liquid chromatograph-tandem mass spectrometry (LC-MS/MS), while ChE activities were assayed using 5,5'-dithiobis(2-nitrobenzoic acid). Distigmine (0.1 mg/kg) significantly increased the maximum intravesical pressure at micturition reflex for 12 h post-administration. In contrast, plasma distigmine was only detectable for 6 h post-administration in these animals and a one-compartment model calculated an elimination half-life of 0.7 h. However, bladder and blood acetylcholinesterase activities were significantly inhibited for 12 h after distigmine administration, although plasma ChE activities were not affected. The pharmacodynamic effects of distigmine thus persisted after its elimination from the circulation, indicating that it may bind to bladder acetylcholinesterase, producing sustained enzyme inhibition and enhancement of bladder contractility.

Galantamine has impact on immunity in mice exposed to keyhole limpet hemocyanin.

OBJECTIVES: In this work, we hypothesized whether galantamine could interact with the cholinergic anti-inflammatory pathway and modulate immunity this way. BACKGROUND: Galantamine is a drug used for the therapy of Alzheimer disease. The drug inhibits enzyme acetylcholinesterase in the central nervous system, which causes better availability of neurotransmitter acetylcholine. METHODS: In the experiment, we immunized BALB/c laboratory mice by keyhole limpet hemocyanin (KLH) in combination with galantamine in a dose 0.02-0.5 mg/kg. The animals were sacrificed from 1 to 7 days after the substances applications and plasma was collected in order to examine immunochemical markers by enzyme-linked immunosorbent assay. RESULTS: We found significant drop in production of immunoglobulins and interleukin (IL) 4 level while IL2, IL4 and tumour necrosis factor α remained unaltered for the whole experiment. We infer that galantamine causes better availability of acetylcholine also in blood system, where the neurotransmitter interacts with nicotinic acetylcholine receptors on macrophages and initiates cholinergic anti-inflammatory pathway. CONCLUSIONS: In a conclusion, galantamine can cause lower efficacy of vaccination or immunity response to an infectious disease and the phenomenon should be taken into consideration in the current therapy (Tab. 1, Fig. 2, Ref. 24).

Development and validation of a simple GC-MS method for the simultaneous determination of 11 anticholinesterase pesticides in blood--clinical and forensic toxicology applications.

Anticholinesterase pesticides are widely used, and as a result they are involved in numerous acute and even fatal poisonings. The aim of this study was the development, optimization, and validation of a simple, rapid, specific, and sensitive gas chromatography-mass spectrometry method for the determination of 11 anticholinesterase pesticides (aldicarb, azinphos methyl, carbofuran, chlorpyrifos, dialifos, diazinon, malathion, methamidophos, methidathion, methomyl, and terbufos) in blood. Only 500 µL of blood was used, and the recoveries after liquid-liquid extraction (toluene/chloroform, 4:1, v/v) were more than 65.6%. The calibration curves were linear (R(2) ≥ 0.996). Limit of detections and limit of quantifications were found to be between 1.00-10.0 and 3.00-30.0 µg/L, respectively. Accuracy expressed as the %E(r) was found to be between -11.0 and 7.8%. Precision expressed as the percent relative standard deviation was found to be <9.4%. The developed method can be applied for the investigation of both forensic and clinical cases of accidental or suicidal poisoning with these pesticides.

Comprehensive gas chromatography with Time of Flight MS and large volume introduction for the detection of fluoride-induced regenerated nerve agent in biological samples.

Recently, several methods have been developed to verify exposure to nerve agents. Most of these methods, such as the fluoride reactivation technique and the analysis of inhibited phosphonylated butyrylcholinesterase (BuChE), are based on mass spectrometry. The high specificity of the mass spectrometer might also imply a disadvantage, because the acquisition mass, i.e. the identity of the analyte must be known beforehand in order to direct the MS analysis in the most sensitive mode. In real cases, the identity of the nerve agent is not always known beforehand and the mass spectrometer should be operated in a scanning mode, with the consequence that sensitivity of the method will be lower. Comprehensive GC, or GC x GC, is a technique which offers enhanced separation. The implied larger selectivity of the GC separation allows mass spectrometry to be conducted in a less specific, scanning, mode. By the use of this configuration, the identity of the nerve agent does not have to be known beforehand but can be traced. In order to be able to detect lower concentrations and assess lower exposure levels, a large volume injection technique was developed allowing sample sizes up to 100 microL. The technique was tested with plasma samples that had been inhibited with various nerve agents. Subsequently, the cholinesterase-bound nerve agent was regenerated by the fluoride reactivation technique. Using the newly developed comprehensive GC-MS method it was possible to detect nerve agent at an exposure level of 1% BuChE inhibition, which is approximately 70 pg nerve agent/mL. These low exposure levels cannot be verified with a cholinesterase (ChE) activity assay. Moreover, the identity of the regenerated nerve agent was verified by the mass spectrum that was generated by the TOF mass spectrometer. This paper presents a technique able to deliver full-scan data on the analysis of nerve agents in biomedical samples at relevant exposure levels (1% BuChE inhibition). This full-scan data meets for a large part the forensic requirements that are in place for the analysis of biomedical samples in the context of alleged use of Chemical Warfare Agents.

Albumin binding as a potential biomarker of exposure to moderately low levels of organophosphorus pesticides.

We have evaluated the potential of plasma albumin to provide a sensitive biomarker of exposure to commonly used organophosphorus pesticides in order to complement the widely used measure of acetylcholinesterase (AChE) inhibition. Rat or human plasma albumin binding by tritiated-diisopropylfluorophosphate ((3)H-DFP) was quantified by retention of albumin on glass microfibre filters. Preincubation with unlabelled pesticide in vitro or dosing of F344 rats with pesticide in vivo resulted in a reduction in subsequent albumin radiolabelling with (3)H-DFP, the decrease in which was used to quantify pesticide binding. At pesticide exposures producing approximately 30% inhibition of AChE, rat plasma albumin binding in vitro by azamethiphos (oxon), chlorfenvinphos (oxon), chlorpyrifos-oxon, diazinon-oxon and malaoxon was reduced from controls by 9+/-1%, 67+/-2%, 56+/-2%, 54+/-2% and 8+/-1%, respectively. After 1 h of incubation with 19 microM (3)H-DFP alone, the level of binding to rat or human plasma albumins reached 0.011 or 0.039 moles of DFP per mole of albumin, respectively. This level of binding could be further increased by raising the concentration of (3)H-DFP, increasing the (3)H-DFP incubation time, or by substitution of commercial albumins for native albumin. Pesticide binding to albumin was presumed covalent since it survived 24 h dialysis. After dosing rats with pirimiphos-methyl (dimethoxy) or chlorfenvinphos (oxon) (diethoxy) pesticides, the resultant albumin binding were still significant 7 days after dosing. As in vitro, dosing of rats with malathion did not result in significant albumin binding in vivo. Our results suggest albumin may be a useful additional biomonitor for moderately low-level exposures to several widely used pesticides, and that this binding differs markedly between pesticides.

Gas chromatography-tandem mass spectrometry analysis of red blood cells from Göttingen minipig following whole-body vapor exposure to VX.

A method to detect fluoride ion generated O-ethyl methylphosphonofluoridate (VX-G) in Göttingen minipig red blood cells (RBC) following whole-body exposure to VX vapor utilizing a gas chromatograph-tandem mass spectrometer (GC-MS-MS) has been developed. Dose-response curves for VX exposure were generated after applying the fluoride ion reactivation assay to the RBC fraction of serially collected whole blood samples that were taken after whole-body exposures that varied in both duration and concentration. GC-MS-MS analysis of minipig RBC samples following 180-min exposures at two different concentrations was a more precise indicator for severity of exposure than the analysis of acetylcholinesterase (AChE) inhibition for the same samples. AChE enzyme activity recovered faster than indicated by the apparent elimination rate of VX-G. GC-MS-MS analyses of RBC samples following VX exposure demonstrate this technique has both adequate sensitivity and specificity to indicate the severity of exposure.

Determination of VX-G analogue in red blood cells via gas chromatography-tandem mass spectrometry following an accidental exposure to VX.

A sensitive method for determining exposure to the chemical warfare agent VX is described in which the biomarker ethyl methylphosphonofluoridate (VX-G) is measured in red blood cells (RBCs) following treatment with fluoride ion using isotope-dilution gas chromatography-tandem mass spectrometry. The analyte was isolated via solid-phase extraction and detected using ammonia chemical ionization in the multiple reaction monitoring mode. A good linear relationship was obtained in the quantitative concentration range of 4 ng/mL to 1000 ng/mL with an absolute detection limit of < 1 pg on column. The method has been applied to the analysis of RBCs from a laboratory worker accidentally exposed to VX vapor. Detection and quantitation of VX-G were possible in samples taken as late as 27 days following exposure.

Verification of exposure to cholinesterase inhibitors: generic detection of OPCW Schedule 1 nerve agent adducts to human butyrylcholinesterase.

Phosphylated butyrylcholinesterase is one of the most important biomarkers to verify an exposure to nerve agents, and it can be analyzed with liquid chromatography-tandem mass spectrometry (LC-MS-MS) by detection of a phosphylated nonapeptide that results after digestion of butyrylcholinesterase (BuChE) with pepsin. For a sensitive analysis (low degree of BuChE inhibition), the identity of the cholinesterase inhibitor has to be known in order to use the LC-MS-MS instrument in the most sensitive selected reaction monitoring mode. In practice, the identity of the cholinesterase inhibitor will not be known beforehand, and the number of possible organophosphates is greater than 1000. However, the number of possible molecular masses of organophosphates is approximately 170. A method for which only 34 transitions in the multiple reaction monitoring mode have to be acquired in order to screen for an exposure to all Organization for the Prohibition of Chemical Weapons Schedule 1 nerve agents was developed.

Determination of pyridostigmine bromide and its metabolites in biological samples.

Pyridostigmine bromide (PB) is a quartenary ammonium compound that inhibits the hydrolysis of acetylcholine by competitive reversible binding to acetylcholinesterase. PB is used for the symptomatic treatment of myasthenia gravis and has been applied as a prophylaxis against nerve agents. Many studies on PB have involved the reliance on techniques that extract and quantify PB in biological samples. This article presents an overview of the currently applied methodologies for the determination of PB and its metabolites in various biological samples. Articles published from January 1975 to the July 2005 were taken into consideration for the discussion of the metabolism and analytical method of PB. HPLC and GC methods have been used and discussed in most of the references cited in this review. Other methods such as RIA and CE that have been recently reported are also mentioned in this article. Basic information about the type of sample used for analysis, sample preparation, chromatographic column, mobile phase, detection mode and validation data are summarized in a table.

Headspace solid-phase microextraction and capillary gas chromatographic-mass spectrometric determination of rivastigmine in canine plasma samples.

A simple, rapid and sensitive method for determination of rivastigmine in plasma samples was developed using headspace solid-phase microextraction (HS-SPME) and gas chromatography with mass spectrometry (GC-MS). The optimum conditions for the SPME procedure were: headspace extraction on a 65-microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber; 0.5 ml of plasma modified with 1.0 ml of sodium hydroxide-sodium carbonate solution (0.7 M:0.5M); extraction temperature of 100 degrees C, with stirring at 2000 rpm for 30 min. The calibration curve showed linearity in the range from 0.2 to 80 ng/ml with regression coefficient corresponding to 0.9965 and coefficient of the variation of the points of the calibration curve lower than 10%. The quantification limit for rivastigmine in plasma was 0.2 ng/ml. The method was applied to determination of rivastigmine in canine plasma samples from animals after a single oral administration.

Use of biomarkers to indicate exposure of children to organophosphate pesticides: implications for a longitudinal study of children's environmental health.

Because of their history of widespread use in the United States and unknown long-term health effects, organophosphate pesticides (OPs) are being considered as a chemical class of interest in planning for the National Children's Study, a longitudinal study of children's environmental health. The availability and appropriate use of biomarkers to determine absorbed doses of environmental chemicals such as OPs are critical issues. Biomarkers of OP exposure are typically measured in blood and urine; however, postpartum meconium has been shown to be a promising matrix for assessing cumulative in utero exposure to the fetus, and studies are currently in progress to determine the utility of using saliva and amniotic fluid as matrices. In this article, we discuss the advantages and disadvantages of the currently available OP exposure monitoring methods (cholinesterase inhibition in blood, pesticides in blood, metabolites in urine and alternative matrices); study design issues for a large, long-term study of children's environmental health; and current research and future research needs. Because OPs are rapidly metabolized and excreted, the utility of one-time spot measurements of OP biomarkers is questionable unless background exposure levels are relatively stable over time or a specific time frame of interest for the study is identified and samples are collected accordingly. Biomarkers of OP exposure can be a valuable tool in epidemiology of children's environmental health, as long as they are applied and interpreted appropriately.

Cholinergic toxic syndrome by the anticancer drug irinotecan: acetylcholinesterase does not play a major role.

BACKGROUND: The anticancer drug irinotecan induces cholinergic side effects that are currently ascribed to the blockade of acetylcholinesterase. This study investigated (1) the pattern of acetylcholinesterase activity in patients receiving treatment with irinotecan and (2) the relationship between acetylcholinesterase activity and plasma concentrations of irinotecan, 7-ethyl-10-hydroxycamptothecin (SN-38), and SN-38 glucuronide (SN-38G). METHODS: Twenty-five patients with advanced colorectal cancer were treated with 250 mg/m(2) irinotecan administered by intravenous infusion for 60 minutes. Blood samples were collected before drug infusion and at 15 minutes and 45 minutes after the start of drug infusion. Blood acetylcholinesterase activity was determined by a colorimetric enzymatic assay, and irinotecan, SN-38, and SN-38G concentrations were determined in plasma by HPLC. The in vitro effects of irinotecan and other drugs on human acetylcholinesterase were also assessed. RESULTS: Compared with basal values, the activity of acetylcholinesterase in blood specimens collected during irinotecan infusion at 15 minutes (-0.76%) and at 45 minutes (-1.50%) showed no changes. No relationships were established between the activity of blood acetylcholinesterase at 15 or 45 minutes and plasma concentrations of irinotecan, SN-38, or SN-38G measured at the same time points. In vitro, the activity of acetylcholinesterase was inhibited by 100-micromol/L irinotecan (-24.8%) and markedly reduced by 1-micromol/L physostigmine (-86.7%), whereas neither SN-38 nor camptothecin had an effect. CONCLUSIONS: Although the use of erythrocyte acetylcholinesterase as a surrogate marker of acetylcholinesterase activity in the nervous system has not been firmly established, our findings do not support the hypothesis that the toxic cholinergic syndrome associated with irinotecan treatment depends on acetylcholinesterase blockade.

Acetylcholinesterase blockade does not account for the adverse cardiovascular effects of the antitumor drug irinotecan: a preclinical study.

This study investigates the mechanisms that account for the adverse cardiovascular effects of the antitumor drug irinotecan. The activities of irinotecan, its active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38), and camptothecin were assayed in urethane-anesthetized rats to determine their effects on heart rate and blood pressure. In vitro experiments were performed to assess the effects of test drugs on acetylcholinesterase activity. Intravenous irinotecan (10 micromol/kg) decreased heart rate and blood pressure, but SN-38, camptothecin, or intracerebroventricular irinotecan had no effect. The bradycardic and hypotensive responses induced by irinotecan were abolished by bilateral vagotomy or atropine. Physostigmine caused a transient bradycardia, followed by a tachycardic response, and promoted a marked increment of blood pressure. Vagotomy or atropine prevented the bradycardic action of physostigmine, whereas the tachycardic and hypertensive responses were sensitive to atropine, but not to vagotomy. Five minutes after irinotecan administration (10 micromol/kg i.v.), its concentration in plasma and atrial tissue accounted for 2.29 +/- 0.19 micromol/L and 1.08 +/- 0.16 micromol/kg, respectively. The in vitro activity of human erythrocyte acetylcholinesterase was significantly inhibited by irinotecan (-21.5% at 100 microM) or physostigmine (-84.8% at 1 microM), whereas SN-38 or camptothecin had no effect. Rat atrial acetylcholinesterase was also significantly inhibited in vitro by irinotecan (-16.9% at 100 microM). The present results indicate that irinotecan exerts depressant effects on both heart rate and arterial blood pressure. A direct activation of cholinergic receptors or an interaction with central nervous sites does not appear to account for these inhibitory actions, whereas a blockade of acetylcholinesterase seems to occur at concentrations of irinotecan that may not be relevant in clinical settings.

Influência de fatores socioeconômicos na contaminaçäo por agrotóxicos, Brasil / Influence of social-economic factors on the pesticine poisoning, Brazil

Objetivo: A elevada utilização de agrotóxicos, sem os cuidados necessários, tem contribuído para a degradação ambiental e o aumento das intoxicações ocupacionais, sendo um dos principais problemas de saúde pública no meio rural brasileiro. O objetivo do trabalho é avaliar a exposição de um grupo de trabalhadores da área rural do Estado do Rio de Janeiro a agrotóxicos anticolinesterásicos, através das atividades da acetilcolinesterase eritrocitária (AChE) e da butirilcolinesterase plasmática (BChE), e o impacto de alguns indicadores socioeconômicos e de utilização de agrotóxicos sobre a contaminação humana. Métodos: Para a avaliação da exposição de 300 agricultores residentes em cinco comunidades do distrito de Magé, RJ, uma amostra aleatória de 55 trabalhadores foi selecionada e determinadas as atividades individuais de acetilcolinesterase eritrocitártia (AChE) e butirilcolinesterase plasmática (BChE). As atividades enzimáticas foram avaliadas segundo o método de Ellman modificado por Oliveira-Silva. Dados socioeconômicos e de utilização de agrotóxicos para cada trabalhador da amostra foram obtidos em entrevista estruturada. O possível papel dos indicadores socioeconômicos e de uso de agrotóxicos sobre o nível de contaminação dos trabalhadores foi estimado por análise de regressão linear múltipla, utilizando-se a atividade enzimática como variável dependente e os indicadores socioeconômicos e de uso de agrotóxicos como variáveis independentes. Resultados e Conclusões: Os dados obtidos mostraram resultados distintos em relação à incidência da exposição excessiva, de acordo com o indicador enzimático utilizado. No grupo de trabalhadores, 3,6 por cento (2) foram identificados pelos resultados de BChE e 41,8 por cento (23) pela AChE, sendo considerados intoxicados indivíduos com pelo menos um dos indicadores positivos. A avaliação desses dados frente aos indicadores socioeconômicos e de utilização de agrotóxicos, destaca a importância do nível de escolaridade sobre a prevalência das intoxicações. Para os demais determinantes estudados, nenhuma correlação significativa foi tão evidente

Plasma tacrine concentrations are significantly increased by concomitant hormone replacement therapy.

BACKGROUND: In vitro results suggest that the synthetic hormones used in postmenopausal hormone replacement therapy (HRT) may be significant inhibitors of oxidative drug metabolism. Moreover, HRT has been reported to enhance response to tacrine in postmenopausal patients with Alzheimer's disease, but the mechanism of this interaction remains unclear. OBJECTIVE: To examine the effect of HRT with 2 mg estradiol valerate and 0.25 mg levonorgestrel once daily on the pharmacokinetics of tacrine. METHODS: Ten healthy female volunteers received treatment for 10 days with once-daily HRT or placebo in a randomized, double-blind crossover study. One hour after the last HRT or placebo capsule on day 10, the subjects received a single 40-mg dose of tacrine. Plasma samples were collected for 30 hours and urine samples were collected for 24 hours after tacrine intake for the measurement of tacrine and 1-hydroxytacrine concentrations. RESULTS: HRT increased the mean plasma concentration-time curve calculated from zero to infinity (AUC) of tacrine by 60% (P = .009); the greatest individual increase in the AUC was about threefold. Similarly, the mean peak concentration in plasma of tacrine was 46% (P = .031) higher in the HRT phase compared with the placebo phase. HRT reduced the mean apparent oral clearance of tacrine by 31% (P = .014), but no significant difference was found in the elimination half-life or the renal clearance of tacrine between the HRT phase and the placebo phase. The metabolic ratio (1-hydroxytacrine AUC/tacrine AUC) was significantly (mean, 26%; P < .001) reduced in all 10 subjects. CONCLUSIONS: HRT with estradiol and levonorgestrel significantly increased plasma tacrine concentrations. This interaction between tacrine and HRT involves reduced metabolic conversion of tacrine to its main metabolite 1-hydroxytacrine by CYP1A2 during the first-pass phase. The interaction may be clinically important with regard to both enhanced efficacy and increased likelihood of concentration-dependent adverse effects of tacrine in the long-term treatment of patients with Alzheimer's disease. Accordingly, smaller doses of tacrine may be appropriate when coadministered with HRT.

Rapid analysis of parathion in biological samples using headspace solid-phase micro-extraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS).

A simple and rapid method for the analysis of parathion in biological samples is presented. The method consists of the extraction of parathion from blood samples by headspace solid-phase micro-extraction (SPME), followed by capillary gas chromatography and mass spectrometry detection. The recoveries in the blood samples after addition of ammonium sulphate and sulphuric acid were between 85% and 89% compared to samples prepared in water. Linearity was established over a concentration range of 0.1-5 microg/g blood with acceptable coefficients of correlation and limits of detection reached 0.02-0.05 microg/g. The time for an analysis is 57 minutes for one sample, including the extraction step. In conclusion, HS-SPME in combination with GC/MS is an effective method for the determination and quantification of parathion-ethyl and parathion-methyl in biological material.