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Environmental contamination by chlorotriazines has been evidenced in mother-child cohort suggesting more detailed risk assessment of these compounds in drinking water. Exposure of rodents to atrazine (ATZ) has been associated with alterations of endocrine and reproductive functions by disrupting neuroendocrine control at hypothalamus level. Perinatal exposure to low doses of ATZ has been associated with reproductive dysfunction, and to behavioral abnormalities in adult exposed during embryogenesis. The objectives of the current investigation were to (1) evaluate the influence of physicochemical properties of chlorotriazines on tissue distribution in pregnant rats and in fetuses and (2) gain a better understanding of fetal distribution of chlorotriazines in specific tissues, particularly in brain. Serial blood samples were obtained from pregnant rats after administration of ATZ, propazine (PRO), and simazine (SIM) via oral route at a dose of 10 mg/kg from day 15 to day 19. Maternal and fetal tissues were harvested at day 20, 24 h after the last dosing. The metabolic extraction ratio was estimated to 87% suggesting a significant first-pass effect explaining the low oral bioavailability. Blood exposure to parent compounds (ATZ, PRO, and SIM) was negligible (lower than 5%) compared with metabolite exposure. The main metabolite exposure involved diamino-s-chlorotriazine, ranging from 60% to 90% depending on the molecules administered. A correlation between tissue-to-blood ratio and physicochemical descriptors was observed for fat and mammary gland tissues but not for brain in adult rats. A more pronounced distribution in fetal brain was observed for ATZ and PRO, the 2 most lipophilic compounds., (© The Author(s) 2019. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The previously-published physiologically based pharmacokinetic model for atrazine (ATZ), deisopropylatrazine (DIA), deethylatrazine (DEA), and diaminochlorotriazine (DACT), which collectively comprise the total chlorotriazines (TCT) as represented in this study, was modified to allow for scaling to humans. Changes included replacing the fixed dose-dependent oral uptake rates with a method that represented delayed absorption observed in rats administered ATZ as a bolus dose suspended in a methylcellulose vehicle. Rate constants for metabolism of ATZ to DIA and DEA, followed by metabolism of DIA and DEA to DACT were predicted using a compartmental model describing the metabolism of the chlorotriazines by rat and human hepatocytesin vitro Overall, the model successfully predicted both the 4-day plasma time-course data in rats administered ATZ by bolus dose (3, 10, and 50 mg/kg/day) or in the diet (30, 100, or 500 ppm). Simulated continuous daily exposure of a 55-kg adult female to ATZ at a dose of 1.0 µg/kg/day resulted in steady-state urinary concentrations of 0.6, 1.4, 2.5, and 6.0 µg/L for DEA, DIA, DACT, and TCT, respectively. The TCT (ATZ + DEA + DIA + DACT) human urinary biomonitoring equivalent concentration following continuous exposure to ATZ at the chronic point of departure (POD = 1.8 mg/kg/day) was 360.6 μg/L., (© The Author 2016. Published by Oxford University Press on behalf of the Society of Toxicology.)

In recent years, there has been a growth in reports of antiepileptic drugs (AEDs) being misused on their own or in combination with other drugs of abuse in a variety of toxicological case types such as drug abuse, suicide, overdose and drug facilitated crime. To our knowledge, there are no simultaneous quantification methods for the analysis of the most commonly encountered AEDs in postmortem whole blood and clinical plasma/serum samples at the same time. A simple, accurate and cost-effective liquid chromatography-tandem mass spectrometric (LC-MS-MS) method has been developed and validated for the simultaneous quantification of carbamazepine (CBZ) and its metabolite CBZ-10,11-epoxide, eslicarbazepine acetate, oxcarbazepine and S-licarbazepine as a metabolite, gabapentin, lacosamide, lamotrigine, levetiracetam, pregabalin, phenobarbital, phenytoin and its metabolite 5-(p-hydroxyphenyl)-5-phenylhydantoin, retigabine (ezogabine) and its metabolite N-acetyl retigabine, rufinamide, stiripentol, topiramate, tiagabine, valproic acid, vigabatrin and zonisamide in postmortem whole blood, serum and plasma which would be suitable for routine forensic toxicological analysis and therapeutic drug monitoring. All AEDs were detected and quantified within 17 min without endogenous interferences. The correlation coefficient (R(2)) was >0.995 for all AEDs with accuracy ranging from 90 to 113% and precision <13% for all analytes. The recovery ranged from 70 to 98%. No carryover was observed in a blank control injected after the highest standard and the matrix effect was acceptable and ranged from 90 to 120%. The method has been successfully verified using authentic case samples that had previously been quantified using different methods., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

This study characterized the concentration-time profile of melamine in the heart, liver, spleen, lungs, kidneys, bladder, feces, urine, and plasma after melamine (MM) administration. Female Sprague-Dawley rats received a single oral dose of 1.0 g/kg body weight. Samples (n=4 per time point) were collected at 12, 24, 48, 72, 96, 120, 144, and 168 h. Based on calculations of the area under the concentration-time curves after dosing, ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) was used to detect MM concentration in tissues. Peak concentrations of MM are reached in the livers and lungs at 12 h after dosing and in hearts, spleens, kidneys, bladders, feces, urine, and plasma at 24 h after dosing. More than 90% of the ingested MM is excreted in feces and urine within 24 h. These results provided initial understanding of the tissue disposition of MM. Moreover, this study demonstrates that UPLC-MS-MS can be used to detect MM in biological samples.

We report a case of fatal intoxication caused by the ingestion of the herbicide Gesapax (an emulsion type), which consists of 25% ametryn (ametryne, ametrin, ametrine, and ametrina), and 75% other components (xylene and cyclohexanone). A female in her 70's was found dead in her bed. Forensic autopsy revealed no remarkable injury or morphological changes. In a gas chromatography-mass spectrometry (GC-MS) screening test, ametryn was qualitatively detected in her stomach content. Then, the other components of xylene and cyclohexanone were detected by headspace GC-MS in the stomach content. The amount of ametryn (microg/g) extract from each body fluid or organ tissue was determined by GC-MS as follows: 6.69 (heart blood), 3.50 (peripheral blood), 0.085 (urine), 17.2 (brain frontal lobe), 71.9 (right lung), 23.9 (liver), 19.1 (right kidney), and 74,200 (stomach contents). The other components, xylene and cyclohexanone, were also determined in the body fluids and organ tissues. These data strongly suggest that the female orally ingested the herbicide. From these toxicological data together with autopsy findings, the cause of her death was determined to be an acute herbicide poisoning.

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS-MS) method has been developed and validated for the determination of lamotrigine in human plasma using multiplexing technique (two HPLC units connected to one MS-MS). Lamotrigine was extracted from human plasma by solid-phase extraction technique using Oasis Hydrophilic Lipophilic Balance (HLB) or N-vinylpyrrolidone and divinylbenzene cartridge. A structural analog, 3,5-diamino-6-phenyl-1,2,4-triazine, was used as an internal standard (IS). A BetaBasic C(8) column was used for the chromatographic separation of analytes. The mass transition [M+H](+) ions used for detection were m/z 256.0 --> 211.0 for lamotrigine and m/z 188.0 --> 143.0 for IS. The method involved a simple multiplexing, rapid solid-phase extraction without evaporation and reconstitution. The proposed method has been validated for a linear range of 0.025 to 10.000 microg/mL with a correlation coefficient > or = 0.9991. The limit of quantification for lamotrigine was 0.025 microg/mL, and limit of detection was 50.000 pg/mL. The intra-run and inter-run precision and accuracy were within 10.0% for intra-HPLC runs and inter-HPLC runs. The overall recoveries for lamotrigine and IS were 97.9% and 92.5%, respectively. Total MS run time was 1.4 min per sample. The validated method has been successfully used to analyze human plasma samples for applications in pharmacokinetic, bioavailability, bioequivalence, or in vitro in vivo correlation studies.

Previously, we reported that atrazine (ATR) alters steroidogenesis in male Wistar rats resulting in elevated serum corticosterone (CORT), progesterone, and estrogens. The increase in CORT indicated that this chlorotriazine herbicide may alter the hypothalamic-pituitary-adrenal axis. This study characterizes the temporal changes in adrenocorticotropic hormone (ACTH), CORT, and P4 in male Wistar rats following a single dose of ATR (0, 5, 50, 100, and 200 mg/kg), simazine (SIM; 188 mg/kg), propazine (PRO; 213 mg/kg), or primary metabolites, deisopropylatrazine (DIA; 4, 10, 40, 80, and 160 mg/kg), deethylatrazine (DEA; 173 mg/kg), and diamino-s-chlorotriazine (DACT; 3.37, 33.7, 67.5, and 135 mg/kg). The maximum dose for each chemical was the molar equivalent of ATR (200 mg/kg). Significant increases in plasma ACTH were observed within 15 min, following exposure to ATR, SIM, PRO, DIA, or DEA. Dose-dependent elevations in CORT and progesterone were also observed at 15 and 30 min post-dosing with these compounds indicating an activation of adrenal steroidogenesis. Measurement of the plasma concentrations of the parent compounds and metabolites confirmed that ATR, SIM, and PRO are rapidly metabolized to DACT. Although DACT had only minimal effects on ACTH and steroid release, dosing with this metabolite resulted in plasma DACT concentrations that were 60-fold greater than that observed following an equimolar dose of ATR and eightfold greater than equimolar doses of DIA or DEA, indicating that DACT is not likely the primary inducer of ACTH release. Thus, the rapid release of ACTH and subsequent activation of adrenal steroidogenesis following a single exposure to ATR, SIM, PRO, DIA, or DEA may reflect chlorotriazine-induced changes at the level of the brain and/or pituitary.

This study describes a simple and sensitive column-switching high-performance liquid chromatographic method with UV detection for the determination of Lamotrigine in 50 microL of serum. After solid-phase extraction of Lamotrigine on an Oasis HLB extraction precolumn (20 x 3.9 mm; dp: 25 microm), chromatographic separation was achieved at 30 degrees C on a Chromolith RP-18e column (50 mm x 4.6 mm i.d.) using a solution of 20% acetonitrile in 15 mM phosphate buffer (pH 7.0) as the mobile phase, at a flow-rate of 2.0 mL/min. The eluant was detected at 215 nm. The retention time for Lamotrigine was 1.28 min. The total analysis time was ca. 5 min. However, the overlap of sample preparation, analysis, and reconditioning of the precolumn increased the overall sample throughput to one injection every 3 min. The method was validated for system suitability, linearity, precision, accuracy, robustness, and limit of quantitation. The linearity of the calibration lines, expressed by the linear correlation coefficient, was better than 0.9996. Recovery studies achieved from Lamotrigine spiked plasma samples showed values greater than 93%, demonstrating the excellent extraction efficiency of the precolumn. Intra- and inter-day precision were generally acceptable; the coefficient of variation was < 2.3% in all cases. The detection limits for Lamotrigine at a signal-to-noise ratio of 3 was 0.002 microg/mL when a sample volume of 50 microL was injected. However, it was possible to enhance the sensitivity further by injecting larger volumes, up to 200 microL. The method was shown to be robust and the results were within the acceptable range. The method was successfully applied to the determination of Lamotrigine in human serum samples of patients submitted to Lamotrigine therapy.

A high-performance liquid chromatography (HPLC) assay using UV detection is described for the simultaneous measurement of the newer generation anti-epileptic medications lamotrigine, oxcarbazepine (parent drug and active metabolite 10- hydroxycarbazepine), and zonisamide. Detection of all four compounds can be done at 230 nm; however, there is a potential interference with zonisamide in patients on clonazepam therapy. Therefore, the method uses dual wavelength detection: 230 nm for oxcarbazepine and 10-hydroxycarbazepine and 270 nm for lamotrigine and zonisamide. In addition, a simple gas chromatography method using a nitrogen-phosphorus detector is described for the measurement of levetiracetam, another of the recently approved anti-epileptic medications. For both methods, limits of quantitation, linearities, accuracies, and imprecisions cover the therapeutic range for drug monitoring of patients. A wide variety of clinical drugs, including other anti-epileptic drugs, do not interfere with these assays. These procedures would be of special interest to clinical laboratories, particularly due to the limited availability of immunoassays for newer generation anti-epileptic medications and that therapeutic uses of these drugs are expanding beyond epilepsy to other neurologic and psychiatric disorders.

Vardenafil (Levitra) is one of the most widely prescribed treatments for erectile dysfunction. This report presents a rapid and reliable method for the identification and quantification of vardenafil in postmortem fluids and tissues, applies this method to a postmortem case, and describes the distribution of vardenafil in various fluids and tissues. This procedure utilizes sildenafil-d8, which is structurally closely related to vardenafil, as an internal standard for more accurate and reliable quantitation. The method incorporates solid-phase extraction and liquid chromatography-tandem mass spectrometry (MS) and MS-MS-MS utilizing an atmospheric pressure chemical ionization ion trap MS in the positive chemical ionization mode. Solid-phase extraction proved to be exceptionally efficient providing recoveries that ranged from 94% to 97%. The limit of detection for vardenafil was determined to be 0.19 ng/mL. The linear dynamic range for this compound was 0.39-200 ng/mL. This method was successfully applied to postmortem fluid and tissue specimens obtained from an aviation accident victim. The distribution of vardenafil in various fluids and tissues and the unusually high concentration of vardenafil in the victim's blood are examined.

The determination of lamotrigine (LTG) simultaneously with carbamazepine (CBZ), carbamazepine 10,11 epoxide (CBZ-E), primidone (PRM), phenytoin (PHT), phenobarbital (PB), and 2-phenyl-2-ethyl-malonamide (PEMA) in human plasma was developed using micellar electrokinetic capillary chromatography (MECC) with a diode-array detector. The reproducibility of both separation and quantitation with MECC analysis were appropriate for the intra- and interassay coefficients. The evaluated drugs concentration intervals of LTG, 0.5-10.0 micro g/mL; CBZ, 1.0-16.0 micro g/mL; PEMA, 1.0-20.0 micro g/mL; PB, 1.0-60.0 micro g/mL; PRM, 1.0-20.0 micro g/mL; PHT, 0.7-40.0 micro g/mL; and CBZ-E, 1.0-14.0 micro g/mL were linear with correlation coefficients higher than 0.987 and coefficients of the variation of the points of the calibration curve lower than 10%. The limit of quantitation of the investigated drugs in plasma varied from 0.5 to 1.0 micro g/mL, depending upon the drug. The MECC technique was sensitive enough to work with microsamples into the subtherapeutic, therapeutic, and toxic concentrations, as well as showed to be simple and efficient when applied to monitoring therapeutic drugs in patients treated with a combination of lamotrigine and other antiepileptic drugs such as hepatic enzyme-inducing agents.

A simple and rapid analytical method is presented for the determination of lamotrigine simultaneously with primidone, carbamazepine, carbamazepine epoxide, phenobarbital, and phenytoin in human plasma using solid-phase microextraction (SPME) and gas chromatography with thermionic specific detection. The best conditions for the SPME procedure is established as following: direct extraction on a 65-microm Carbowax-divinylbenzene fiber; 1.0 mL of a sample plasma matrix modified with 15% NaCl and 3 mL of a potassium phosphate buffer (pH 7.0); extraction temperature at 30 degrees C; and stirring at a rate of 2500 rpm for 15 min. The method shows good linearity between 0.05 and 40.0 microg/mL with regression coefficients ranging between 0.9965 and 0.9995 and a coefficient of variation of the points of the calibration curve lower than 10%. The lowest limit of quantitation for the plasma-investigated drugs varies from 0.05 to 0.20 microg/mL, according to the drug. The proposed method is sensitive enough to work into subtherapeutic and therapeutic concentrations, being that it is applied in pharmacokinetic studies and patient routine therapeutic drug monitoring.

An in vivo-in vitro model was used to assess the antimalarial activity of PS-15 and its metabolite, WR99210, against Plasmodium falciparum. WR99210, an antifolate triazine compound, was given as a single oral dose of 30 mg/kg to 8 Saimiri sciureus monkeys and, 3 months later, the parent compound, PS-15, was given similarly to the same monkeys. Serum samples were collected at various times after drug administration, serially diluted with control serum, and their antimalarial activity in vitro was determined against the multidrug-resistant K1 isolate of P. falciparum. Serum concentrations of PS-15 and WR99210 were estimated by high performance liquid chromatography. The maximum dilutions of serum that inhibited parasite growth were 20- to 86-fold higher 3 and 6 h after administration of PS-15 than following WR99210 administration. Substantial serum antimalarial activity was observed even at 48 h after medication with PS-15. Serum drug concentrations provided further evidence that PS-15 was absorbed far better from the gastrointestinal tract than WR99210. The substantial and sustained activity of PS-15 suggests that a single dose, or several smaller doses given once a day, should be effective in curing drug-resistant infections of P. falciparum.

Extensive metabolizers (EM) and poor metabolizers (PM) of the malaria chemoprophylactic drug proguanil have been identified by measuring the proguanil/cycloguanil ratio in urine following a single dose of the pro-drug. The pharmacokinetic characteristics of proguanil were similar in 8 EM and 8 PM subjects, but there were significant differences between the 2 groups with respect to cycloguanil pharmacokinetics. In none of the PM subjects could cycloguanil be detected in whole blood samples at any time after proguanil dosage. Plasma cycloguanil was measureable in only 2 of 8 PM subjects, despite an analytical sensitivity in the high-performance liquid chromatographic assay of 1 ng/ml cycloguanil. A comparatively high proportion of Black Kenyan adults appear to metabolize proguanil poorly, possibly because they lack the specific mixed function oxidase which will accept proguanil as substrate.