Simultaneous determination of bentazone and its metabolites in postmortem whole blood using liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry method with solid-phase extraction (SPE) was developed and validated for the detection and quantitation of bentazone and its two hydroxylated metabolites, 6-hydroxybentazone and 8-hydroxybentazone, in postmortem blood. Sample cleanup was performed using a hydrophilic-lipophilic balanced (HLB) SPE cartridge and then separated on a C18 LC column using a gradient elution of 0.1% formic acid in distilled water and 0.1% formic acid in methanol. The identification of bentazone and its hydroxylated metabolites was performed using tandem mass spectrometry with electrospray ionization in negative ion mode with selective reaction monitoring. The retention times of bentazone, 6-hydroxybentazone, 8-hydroxybentazone, and 2-methyl-4-chlorophenoxyacetic acid (MCPA, internal standard) appeared separately in the chromatogram. The matrix effect, recovery, and process efficiency of bentazone were 75.3%, 103.6% and 77.9%, respectively. In addition, good accuracy (88.2-110.5%), precision (0.5-7.5%, bias), and linearity (5-500ng/mL) were obtained with this method. The limit of detection (LOD) of bentazone, 6-hydroxybentazone, and 8-hydroxybentazone were 0.05, 0.5, and 0.5ng/mL, respectively. The method developed herein was applied to authentic samples from three fatal cases from 2016 for the determination of the corresponding bentazone and its metabolites levels. The concentration ranges of bentazone, 6-hydroxybentazone, and 8-hydroxybentazone in the heart blood from the three victims were 46.0-91.8, 4.2-6.2, and 0.2-0.6µg/mL, respectively.

Neuropharmacokinetics of a new alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) modulator, S18986 [(S)-2,3-dihydro-[3,4]cyclopentano-1,2,4-benzothiadiazine-1,1-dioxide], in the rat.

The aim of our study was to determine the neuropharmacokinetics of S18986 [(S)-2,3-dihydro-[3,4]cyclopentano-1,2,4-benzothiadiazine-1,1-dioxide], a new positive allosteric modulator of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid-type receptors, in the rat. We focused on its blood-brain barrier (BBB) uptake and on its brain intra- and extracellular fluid (bICF-bECF) partitioning. BBB transport of S18986 was measured using the in situ brain perfusion technique. bECF concentrations were determined by microdialysis in the two effector areas, i.e., frontal cortex (FC) and dorsal hippocampus (DH), and blood samples were collected simultaneously through a femoral catheter. Cerebrospinal fluid and brain tissue concentrations were determined using a conventional pharmacokinetic approach. Using all the experimental data, pharmacokinetic modeling was applied to describe the S18986 blood-brain disposition. The brain uptake clearance of S18986 was found to be high, about 20 mul s(-1) g(-1). Terminal half-lives were similar in plasma and brain, at around 1 h. Experimental and predicted blood and brain concentrations were a good fit with the pharmacokinetic model, which assumed first-order rate constants at each interface. Ratios of bECF to the unbound plasma area under the curve (AUC) were 0.24 in FC and 0.25 in DH, whereas ratios of bICF/plasma AUC were 1 in FC and 1.5 in DH. We conclude that despite the ratio of bECF/plasma AUC below 1, there is nevertheless an elevated BBB uptake of S18986. This can be explained by the S18986 nonhomogenous bECF/bICF partitioning, since S18986 mainly distributes into hippocampal bICF. This illustrates the importance of taking bECF/bICF partitioning into account when interpreting the neuropharmacokinetics of a drug.

Fatal overdose of the herbicide bentazone.

A 59-year-old woman who intentionally ingested 100-200 ml Basagran was taken to the hospital with a cardiac arrest 2 days after she had consumed the herbicide. During this period she suffered vomiting, urination and diarrhoea and she was drowsy with a muddled speech. Biological samples obtained at the autopsy were analysed and presence of bentazone, alcohol and an active metabolite of citalopram were detected. Blood concentrations of bentazone, alcohol and desmethyl-citalopram were 625 mg/kg, 0.62 g/l and 0.03 mg/kg, respectively.

Fatal acute poisoning by bentazon.

A case of fatal suicidal bentazon poisoning is presented along with a description of the different analytical methods involved. A 56-year-old farmer was examined by the family doctor 1 h after voluntarily ingesting 500 mL of FIGHTER (bentazon, 480 g/L water). He presented a Glasgow score of 15, polypnea, diarrhea, and vomiting. During transport by ambulance to the hospital, he tossed, sweated, and suddenly presented breathing difficulty followed by heart failure. Tracheal intubation was impossible (H1.5) despite use of different diameter cannulas because of extreme general muscle rigidity. All attempts at resuscitation failed, and the patient died within 2 h postingestion. Blood and urine samples were taken just before death. General basic and neutral drug screening by high-performance liquid chromatography-diode-array detection and gas chromatography-nitrogen-phosphorus detection showed no strychnine or other drugs or toxics except for citalopram (< 0.1 mg/L) and bentazon, but this weak acidic molecule (pKa3.3) was badly extracted in alkaline conditions. Plasma and urine levels, measured after acidic extraction, protein precipitation, or simple dilution, were 1500 and 1000 mg/L, respectively. Bentazon (M.W. 240) was confirmed by its basic mass spectrum (ESI-, m/z 239, 197, 175, 132) or by that of methylated derivative (El+, m/z 254, 212, 175). An hydroxylated metabolite (ESI-, m/z 255, 213, 191, 148; El+, m/z 284, 242, 163) and the N1-glucuronide conjugate of bentazon (ESI-, m/z 415, 239) were also detected in urine. (Quantitation ions are underlined.) This first case of bentazon poisoning with available analytical data revealed the high toxicity of this compound after large dose ingestion with early and heavy symptoms such as muscle rigidity probably related to muscular toxicity. Comparison with another nonfatal case and with toxicological data on animals is discussed.

Interaction of benzothiadiazides with human serum albumin studied by dialysis and spectroscopic methods.

The interaction of a series of benzothiadiazides with human serum albumin (HSA) was investigated by equilibrium dialysis (ED) and spectroscopic methods including circular dichroism (CD). The primary binding site of benzothiadiazides was designated site II, the diazepam site on the HSA molecule, as indicated by displacement experiments using different site-selective probes. Tyrosine and lysine amino acid residues were probably involved in the binding site of these compounds to HSA. Both electrostatic and hydrophobic interactions were found to play a role in the binding of these compounds to HSA. Among the compounds tested, chlorothiazide had the highest affinity (K1 = 5.5 x 10(4) M-1, K2 = 5.8 x 10(3) M-1). The primary binding affinity of the compounds for HSA was of the order: chlorothiazide > cyclopenthiazide > polythiazide > ethiazide > trichlormethiazide = methyclothiazde > hydrochlorothiazide. Binding was insensitive to the N-B transition of HSA. The binding site is proposed to consist of a cationic site on the surface of the HSA molecular with a hydrophobic crevice to accommodate the aromatic ring of the compounds. Positions 3 and 7 of the benzothiadiazide molecule is thought to affect the binding affinity to HSA.

Determination of 7-chloro-3-(4-methyl-1-piperazinyl)-4h-1,2,4-benzothiadiazine-1,1-dioxide (DU-717) in plasma using electron-capture gas chromatography.

A gas chromatographic method has been developed which enables accurate determination of a new antihypertensive agent, DU-717, in plasma. DU-717 is first extracted with ethyl acetate and, after a clean-up procedure, derivatized with peracetic acid followed by diazomethane to form 2-methyl DU-717 N-oxide (direct methylation leads to mixtures). The N-oxide is then pyrolyzed to 2-methyl DU-717 on a gas chromatograph equipped with electron-capture detection. Accurate determinations are possible over a concentration range from 10 to 150 ng/ml of DU-717 in plasma at a relative standard deviation of 6.2%. The minimum detectable concentration is 1 ng/ml. Plasma levels of DU-717 in spontaneously hypertensive and normotensive rats following single oral administrations (10 mg/kg) have also been determined.