A novel nanozyme doped ZnO/r-GO-based sensor for highly sensitive electrochemical determination of muscle-relaxant drug: cyclobenzaprine HCl.

A nanocomposite of Ce-doped ZnO/r-GO was synthesized using a conventional hydrothermal method. The synthesized nanocomposites were utilized for the purpose of sensitive and selective detection of cyclobenzaprine hydrochloride (CBP). The properties of the composite were extensively analyzed, including its morphology, structure, and electrochemical behavior. This study investigates the application of a modified glassy carbon electrode for the detection of CBP, a muscle relaxant used to treat musculoskeletal diseases that cause muscle spasms. The electrode is modified with Ce-doped ZnO/r-GO. Various detection methods, such as cyclic voltammetric and square wave techniques (SWV), were utilized. The composite material showed high effectiveness as an electron transfer mediator in the oxidation of CBP. The electrode showed a good response for SWV evaluations in CBP identification, with a minimum detection limit of 1.6 × 10-8 M and a wide linear range from 10 × 10-6 M to 0.6 × 10-7 M, under ideal conditions. The rate constant for charge transfer (ks) and the estimation of the electrochemical active surface area were obtained. A developed sensor exhibited desirable selectivity, long-lasting stability, and remarkable reproducibility. A sensor was used to analyze water, human serum, and urine samples, resulting in positive recovery results.

Just say no to postmortem drug dose calculations.

For years, a number of professional groups have warned forensic and clinical toxicologists against calculating an administered dose of a drug based on postmortem blood drug concentrations. But to date, there has been limited information as to how unreliable these dose calculations may actually be. Using amitriptyline as a model drug, this study used empirically determined pharmacokinetic variables for amitriptyline from clinical studies coupled with clinical overdoses (where the individual survived), and death case studies (ascribed to amitriptyline toxicity) in which the dose of amitriptyline was known. Using these data, standard pharmacokinetic equations, and general error propagation, it was possible to estimate the accuracy of calculated doses of amitriptyline, compared with the doses that were consumed. As was expected in postmortem cases, depending on the pharmacokinetic equation used, the accuracy (mean +128% to +2347%) and precision (SD ± 383% to 3698%) were too large to allow reliable estimations of the dose of amitriptyline consumed prior to death based on postmortem blood drug concentrations. This work again reinforces that dose calculations from postmortem blood drug concentrations are unreliable.

Green HPLC-DAD and HPTLC Methods for Quantitative Determination of Binary Mixture of Pregabalin and Amitriptyline Used for Neuropathic Pain Management.

First analytical methods were herein developed for determination of pregabalin (PGB) and amitriptyline (AMT) as an active binary mixture used for management of neuropathic pain whether in pure forms or in human biological fluids (plasma/urine). First method is green high-performance liquid chromatography-diode array detector (HPLC-DAD) after derivatization of PGB with ninhydrin (NIN) on a reversed-phase C18 column using a mobile phase consisting of ethanol:water (97:3%, v/v) pumped isocratically at 0.8 mL/min; AMT were scanned at 215 nm, whereas PGB-NIN was scanned at 580 nm. Second method is High-performance thin-layer chromatography (HPTLC), where PGB and AMT were separated on silica gel HPTLC F254 plates, using ethanol:ethyl acetate:acetone:ammonia solution (8:2:1:0.05, by volume) as a developing system. AMT peaks were scanned at 220 nm, whereas PGB peaks were visualized by spraying 3% (w/v) ethanolic NIN solution and scanning at 550 nm. Linear calibration curves were obtained for human plasma and urine spiked with PGB and AMT over the ranges of 5-100 µg/mL and 0.2-2.5 µg/band for PGB, and 1-100 µg/mL and 0.1-2.0 µg/band for AMT for HPLC-DAD and HPTLC methods, respectively. The suggested methods were validated according to Food and Drug Administration guidelines for bioanalytical methods validation and they can be applied for routine therapeutic drug monitoring for the concerned drugs.

Role of serum amitriptyline concentration and CYP2C19 polymorphism in predicting the response to low-dose amitriptyline in irritable bowel syndrome.

BACKGROUND: Low-dose amitriptyline (AMT) is an effective treatment for diarrhea-dominant irritable bowel syndrome (IBS-D). Its efficacy depends upon its serum concentration and the patient's CYP2C19 genotype. AIMS: To identify the association between serum AMT and nortriptyline (NT) concentration and CYP2C19 polymorphism and the clinical response in IBS-D patients. METHODS: Ninety IBS-D patients were treated of AMT for 6 weeks. Efficacy was evaluated by the results of the Adequate Relief question each week and an IBS severity scoring system (IBS-SSS) at 0, 3, and 6 weeks. CYP2C19 genotyping was performed by direct sequencing. AMT and NT steady-state serum concentrations were detected by high-performance liquid chromatography. RESULTS: The CYP2C19 polymorphism exhibited a significant influence on the NT serum concentration but did not predict the clinical efficacy of AMT for treating IBS-D. The NT steady-state and dose-corrected serum concentrations were significantly correlated with an improvement in the IBS-SSS score after 6 weeks, whereas the AMT serum concentration was not correlated with clinical improvement. The cut-off NT steady-state serum concentration of 2.91 ng/ml may help distinguish responders from non-responders. CONCLUSIONS: NT serum concentration but not CYP2C19 polymorphism may be correlated with the clinical efficacy of AMT for treating IBS-D, and such a response may occur at the upper NT threshold of 2.91 ng/ml.

Bioequivalence Study of Amitriptyline Hydrochloride Tablets in Healthy Chinese Volunteers Under Fasting and Fed Conditions.

PURPOSE: This study compares the pharmacokinetic and safety profiles between a new generic and a branded reference formulation of amitriptyline hydrochloride tablets, and assesses the bioequivalence of the two products in healthy Chinese volunteers to obtain sufficient evidence for the marketing approval of the generic drug. MATERIALS AND METHODS: A randomized, open-label, two-period crossover study (clinicaltrials.gov, NCT03646526) was conducted under both fasting and fed conditions in healthy Chinese volunteers (24 subjects/condition). Eligible subjects randomly received a single 25 mg dose of either the test or the reference formulation, followed by a 3-week washout period. Blood samples were collected until 144 h following administration. The pharmacokinetic parameters were acquired based on the concentration-time profiles, including the areas under the plasma concentration-time curve (AUC0-t, AUC0-∞), the peak plasma concentration (Cmax), the time to achieve Cmax (Tmax), and the elimination half-life (t1/2). The geometric mean ratios (GMRs) and the corresponding 90% confidence intervals (CIs) of amitriptyline were acquired for bioequivalence analysis, and values of these parameters for nortriptyline were used for comparison of therapeutic outcomes. Safety assessments included laboratory tests, physical examination, vital signs, and incidence of adverse events (AEs). RESULTS: The values of t1/2 and Tmax for amitriptyline were not significantly different between the test and reference products under both fasting and fed conditions (P > 0.05). The GMRs of Cmax, AUC0-t, and AUC0-∞ between the two products, and corresponding 90% CIs, were all within the range of 80% to 125% under both fasting and fed conditions. The test and reference products were well tolerated and did not elicit serious adverse events. CONCLUSION: This study demonstrated that the generic and reference products were well tolerated by the subjects and bioequivalent, according to the rate and extent of the drug absorption.

Pharmacokinetic study of oral amitriptyline in horses.

The purpose of this study was to evaluate the pharmacokinetics of oral amitriptyline in horses. Oral amitriptyline (1 mg/kg) was administered to six horses. Blood samples were collected from jugular and lateral thoracic vein at predetermined times from 0 to 24 hr after administration. Plasma concentrations were determined by high-performance liquid chromatography and analyzed using noncompartmental methods. Pharmacodynamic parameters including heart rate, respiration rate, and intestinal motility were evaluated, and electrocardiographic examinations were performed in all subjects. The mean maximum plasma concentration (Cmax ) of amitriptyline was 30.7 ng/ml, time to maximum plasma concentration (Tmax ) 1-2 hr, elimination half-life (t1/2 ) 17.2 hr, area under plasma concentration-time curve (AUC) 487.4 ng ml-1  hr-1 , apparent clearance (Cl/F) 2.6 L hr-1  kg-1 , and apparent volume of distribution (Vd/F) 60.1 L/kg. Jugular vein sampling overestimated the amount of amitriptyline absorbed and should not be used to study uptake following oral administration. Heart rate and intestinal motility showed significant variation (p < .05). Electrocardiography did not provide conclusive results. Further studies are required to discern if multiple dose treatment would take the drug to steady state as expected, consequently increasing plasma concentrations.

Polyoxomolybdate368 /polyaniline nanocomposite as a novel fiber for solid-phase microextraction of antidepressant drugs in biological samples.

A novel solid-phase microextraction fiber was synthesized by coating a stainless steel wire with polyoxomolybdate368 /polyaniline as a sorbent aimed at extraction of amitriptyline, nortriptyline, and doxepin as antidepressant drugs from urine and blood samples. The polyoxomolybdate368 /polyaniline composite coating was applied using electropolymerization process under constant potential. This composition leads to enhanced extraction efficiency of the fiber. Scanning electron microscopy images show that huge three-dimensional structures of polyoxomolybdate368 in composite induced more non-smooth and porous fiber. In order to optimize of the extraction process, a series of variables including concentration of the composite materials, coating thickness, pH, extraction time, salt addition, and stirring rate was investigated and optimum conditions were determined. Analysis of surface morphology and chemical composition was performed. High-performance liquid chromatography was used for separation and evaluation of mentioned antidepressant drugs from the matrixes. The experiments indicated a detection limits of <0.2 ng/L and a linear dynamic range of 0.3-100 ng/L (R2  > 0.994). The relative recovery values were found to be in the range of 92-98%. It was concluded that the purposed fiber is highly efficient in analyzing traces of antidepressant drugs in urine and blood.

Nortriptyline serum concentration as a predictor for cardiac risk in amitriptyline-treated patients.

PURPOSE: Tricyclic antidepressants have been shown to affect electrocardiogram (ECG) parameters, but there is limited evidence in relation to the serum concentrations. Therefore, we aimed to evaluate a prediction of cardiac risk in amitriptyline- and doxepin-treated patients by serum concentrations. PATIENTS AND METHODS: The association between serum concentrations of amitriptyline (n = 100) and doxepin (n = 71) and ECG parameters was retrospectively examined using linear regression analysis. Mann-Whitney U tests were applied to evaluate differences in QTc intervals in patients with serum concentrations above and below the upper limit of the therapeutic reference range, as well as the alert level of each target drug. RESULTS: The sum serum concentration of amitriptyline and the nortriptyline serum concentration were significantly associated with an increased PQ interval (p = 0.020, p = 0.007), as well as with increased QTcB (p = 0.012, p < 0.001) and QTcF intervals (p = 0.025, p < 0.001). The nortriptyline concentration was significantly associated with the QRS interval (p = 0.003). In patients with active moiety concentrations above the alert level (300 ng/ml) and nortriptyline concentrations above the reference range (170 ng/ml), the QTcB interval was significantly prolonged (p = 0.032, p = 0.007). No significant association with any ECG parameter was detected for doxepin serum concentrations. CONCLUSION: The effect of amitriptyline on ECG parameters may be explained by nortriptyline alone. Accordingly, with increasing nortriptyline concentrations, the potential risk for an atrioventricular block, a bundle branch block, and prolongation of QTc interval may increase significantly.

Practical liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of amitriptyline, nortriptyline and their hydroxy metabolites in human serum.

Amitriptyline (AMI) has been in use for decades in treating depression and more recently for the management of neuropathic pain. A highly sensitive and specific LC-tandem mass spectrometry method was developed for simultaneous determination of AMI, its active metabolite nortriptyline (NOR) and their hydroxy-metabolites in human serum, using deuterated AMI and NOR as internal standards. The isobaric E-10-hydroxyamitriptyline (E-OH AMI), Z-10-hydroxyamitriptyline (Z-OH AMI), E-10-hydroxynortriptyline (E-OH NOR) and Z-10-hydroxynortriptyline (Z-OH NOR), together with their parent compounds, were separated on an ACE C18 column using a simple protein precipitation method, followed by dilution and analysis using positive electrospray ionisation with multiple reaction monitoring. The total run time was 6 min with elution of E-OH AMI, E-OH NOR, Z-OH AMI, Z-OH NOR, AMI (+ deuterated AMI) and NOR (+ deuterated NOR) at 1.21, 1.28, 1.66, 1.71, 2.50 and 2.59 min, respectively. The method was validated in human serum with a lower limit of quantitation of 0.5 ng/mL for all analytes. A linear response function was established for the range of concentrations 0.5-400 ng/mL (r2 > .999). The practical assay was applied on samples from patients on AMI, genotyped for CYP2C19 and CYP2D6, to understand the influence of metaboliser status and concomitant medication on therapeutic drug monitoring.

Commutability of proficiency testing material containing amitriptyline and nortriptyline: A study within the framework of the Dutch Calibration 2.000 project.

BACKGROUND: External quality assessment schemes (EQAS) can provide important information regarding accuracy and comparability of different measurement methods if the sample matrices are composed of commutable material. The aim of this study was to assess the commutability of different matrices for the material used in an EQAS for amitriptyline and nortriptyline. METHODS: Proficiency testing material (PTM) and patient samples containing amitriptyline and nortriptyline were prepared, collected, pooled, and distributed to participating laboratories for analysis. Low, medium and high concentrations of both drugs in liquid pooled human, lyophilized human and lyophilized bovine serum were tested in this study. The measurement deviation of the PTM results to the patient serum regression line were normalized by dividing trough the average within-laboratory SD (SDwl) derived from the results reported in the official EQAS, resulting in a relative residual. The commutability decision limit was set at 3 SDwl. RESULTS: With 10 laboratories participating in this study, 45 laboratory couples were formed. All matrix types delivered several relative residuals outside the commutability decision limit. The number and the magnitude of relative residuals for both drugs were lower for liquid human sera as compared to lyophilized human and bovine sera. CONCLUSIONS: The PTM used for amitriptyline and nortriptyline is preferably prepared with human serum, although not all relative residuals are within the commutability decision limit.

An improved fabric phase sorptive extraction method for the determination of five selected antidepressant drug residues in human blood serum prior to high performance liquid chromatography with diode array detection.

Fabric phase sorptive extraction (FPSE), a recently introduced sorbent-based microextraction technique, was applied for the first time in order to achieve a simple and rapid simultaneous extraction of five common antidepressant drug residues (venlafaxine, paroxetine, fluoxetine, amitriptyline and clomipramine) from human blood serum. Elimination of protein precipitation step and minimized solvent consumption led to a sample preparation workflow compliant with the principles of green analytical chemistry (GAC). FPSE utilizes permeable and flexible fabric substrate chemically coated with a sol-gel organic-inorganic hybrid sorbent as the extraction device. Among all the membrane examined, sol-gel polycaprolactone-dimethylsiloxane-polycaprolactone coated polyester substrate presented optimum extraction efficiency and was found to be reusable for at least 30 times. The selected drugs were analyzed and detected by reversed phase high performance liquid chromatography method using gradient elution and a diode array detector operated at 235 nm. Limit of detection was found 0.15 ng µL-1, while good absolute recoveries (9.4-88.1%) and low relative standard deviations (≤9.2% and ≤ 11.0 for within-day and between-day precision, respectively) were obtained.

Experimental and Clinical Pharmacokinetics of Fluoxetine and Amitriptyline: Comparative Analysis and Possible Methods of Extrapolation.

The pharmacokinetics of two fluoxetine capsulated dosage forms and two amitriptyline tablet forms after a single oral intake was studied in dogs and healthy volunteers. High significant correlations were detected between plasma concentrations of fluoxetine (r=0.96, p<0.00001, n=11) and amitriptyline (r=0.78, p<0.0224, n=8) in dogs and volunteers. A correlation of medium strength (though insignificant) was detected between nortriptyline concentrations in the plasma of dogs and volunteers (r=0.69, p<0.199, n=5). The bioavailability parameters of the test drugs in dogs and volunteers did not differ. Similar trends of fluoxetine and amitriptyline pharmacokinetic parameters were revealed in volunteers and animals. Methods for extrapolation of experimental pharmacokinetics parameters of fluoxetine and amitriptyline obtained on dogs for humans are proposed and validated.

Dexamethasone changes the pharmacokinetics of amitriptyline and reduces its accumulation in rat brain: The roles of P-gp and cyp3a2.

The wide spread use of central nervous system (CNS) drugs has caused thousands of deaths in clinical practice while there are few antidotes or effective treatments to decrease their accumulation in CNS. In this study, we used amitriptyline (AMI) and dexamethasone (DEX) as the corresponding poisoning and pre-protecting drugs, respectively, to study whether DEX has the potential to reduce AMI accumulation in brain. By measuring the pharmacokinetic data of AMI and its main metabolite nortriptyline (NOR), we found that DEX possibly accelerated the metabolism and elimination of AMI with minimal effects on the concentrations of NOR in blood. Nevertheless, the results indicated that DEX reduced the brain/plasma concentration ratio of AMI and NOR, even if the plasma concentration of NOR had an upward trend. Western blot results showed the overexpression of cyp3a2 and P-gp in rat liver and brain capillaries tissues. We propose that cyp3a2 and P-gp could be upregulated in the liver and blood-brain barrier (BBB) when using DEX. Further experiments suggest that DEX may serve as the ligand of PXR to induce P-gp expression.

High-Precision Quantitation of Biofluid Samples Using Direct Mass Spectrometry Analysis.

The transition of mass spectrometry for clinical analysis is highly desirable, and major progress has been made with direct sampling ionization for operation simplification. High-precision quantitation, however, remains a major challenge in this transition. Herein, a novel method was developed for direct quantitation of biofluid samples, using an extremely simplified procedure for incorporation of internal standards selected against the traditional rules. Slug flow microextraction was used for the development, with conditions predicted by a theoretical model, viz., using internal standards of partition coefficients very different from the analytes and large sample-to-extraction solvent volume ratios. Direct quantitation of drug compounds in urine and blood samples was demonstrated. This development enabled an extremely simplified protocol that is expected to have a significant impact on on-site or clinical analysis.

QTc Time Correlates with Amitriptyline and Venlafaxine Serum Levels in Elderly Psychiatric Inpatients.

INTRODUCTION: Many antidepressants cause QT prolongation but the classification of cardiac risk of these drugs varies markedly in different published lists. This retrospective study analyzed the correlation of QTc time with amitriptyline and venlafaxine serum level in elderly psychiatric inpatients. METHODS: Elderly inpatients aged≥65 years for whom venlafaxine or amitriptyline serum level had been measured were selected retrospectively from a therapeutic drug monitoring database and screened for an electrocardiogram measurement at the time of blood withdrawal. The correlation of amitriptyline or venlafaxine serum levels with QTc time was examined by using Pearson's correlation analysis. RESULTS: Amitriptyline serum levels (n=11) correlated significantly with QTc time (r=0.918, p<0.001, CI 95%). Venlafaxine serum levels (n=27) also correlated significantly with QTc time (r=0.382, p<0.05, CI 95%). DISCUSSION: Amitriptyline and venlafaxine induce QT prolongation depending on drug concentrations in blood. Its extent, however, is very low when drug serum levels are within the therapeutic range. Future pharmacokinetic studies that correlate drug serum level and QT time should classify the cardiac risk of drugs based on the grade of the regression line in relation to the therapeutic range.

High-throughput paper spray mass spectrometry via induced voltage.

RATIONALE: Paper spray (PS) has been developed as a method of choice for point-of-care analysis in many real cases, where its applications can be further expanded with delicate high-throughput design. To achieve this goal, we developed a new PS regime, with the assembly of an induced high voltage into the ion source. Compared with regular DC high voltage, the newly developed setup is capable of high-throughput, simple configuration and rapid switching between individual papers without complicated electric/mechanic design. METHODS: A device of high-throughput induced PS (IPS) was designed by using a two-dimensional (2D) rotating platform equipped with a circular glass plate. The paper substrate was placed on the circular glass plate and separated from the electrode. The method avoids physical contact between the electrode and the sample. Charged droplets were generated at the paper tip once an induced high voltage was applied to a wet paper. RESULTS: A relatively rapid analytical speed of 2.6 s per sample was achieved via IPS-MS. Rapid quantification of amitriptyline (AMT) in complicated matrices was obtained within 1 min using an isotope internal standard method. Limits of detection for AMt in urine, FBS and blood were calculated to be 1.04, 0.84 and 1.33 ng/mL, respectively. In addition, high-throughput IPS-MS can be used for chemical reaction monitoring. CONCLUSIONS: We have demonstrated the versatility of high-throughput IPS-MS in ambient ionization, which successfully simplified the experimental installation and facilitated the experimental operation. Therefore, we believe that high-throughput IPS-MS analysis will be widely used for discovering drugs and screening reactions, and the present design has the potential for applications in paper chip-MS analysis.

Analysis of smoking behavior on the pharmacokinetics of antidepressants and antipsychotics: evidence for the role of alternative pathways apart from CYP1A2.

Smoking is common among psychiatric patients and has been shown to accelerate the metabolism of different drugs. We aimed to determine the effect of smoking on the serum concentrations of psychopharmacological drugs in a naturalistic clinical setting. Dose-corrected, steady-state serum concentrations of individual patients were analyzed retrospectively by linear regression including age, sex, and smoking for amitriptyline (n=503), doxepin (n=198), mirtazapine (n=572), venlafaxine (n=534), clozapine (n=106), quetiapine (n=182), and risperidone (n=136). Serum levels of amitriptyline (P=0.038), clozapine (P=0.02), and mirtazapine (P=0.002) were significantly lower in smokers compared with nonsmokers after correction for age and sex. In addition, the ratios of nortriptyline/amitriptyline (P=0.001) and nordoxepin/doxepin (P=0.014) were significantly higher in smokers compared with nonsmokers. Smoking may not only induce CYP1A2, but may possibly also affect CYP2C19. Furthermore, CYP3A4, UGT1A3, and UGT1A4 might be induced by tobacco smoke. Hence, a different dosing strategy is required among smoking and nonsmoking patients. Nevertheless, the clinical relevance of the results remained unclear.

Dried blood spots and parallel artificial liquid membrane extraction-A simple combination of microsampling and microextraction.

In this paper, parallel artificial liquid membrane extraction (PALME) was used for the first time to clean-up dried blood spots (DBS) prior to ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Fundamental studies exploring amongst others desorption from the DBS in alkaline or acidic aqueous conditions, total extraction time and absolute recoveries were executed. Desorption and PALME were performed using a set of two 96-well plates, one of them housing the sample and the other comprising the supported liquid membrane (SLM) and the acceptor solution. In one procedure, amitriptyline and quetiapine (basic model analytes) were desorbed from the DBS using 250 µL of 10 mM sodium hydroxide solution (aqueous), and subsequently extracted through the SLM consisting of 4 µL of 1% trioctylamine in dodecyl acetate, and further into an acceptor solution consisting of 50 µL of 20 mM formic acid. In a second procedure, ketoprofen, fenoprofen, flurbiprofen, and ibuprofen (acidic model analytes) were desorbed from the DBS into 20 mM formic acid, extracted through an SLM with dihexyl ether, and further into an acceptor solution of 25 mM ammonia. Within 60 min of PALME, both basic and acidic model analytes were effectively desorbed from the DBS and extracted into the acceptor solution, which was injected directly into the analytical instrument. Recoveries between 63 and 85% for the six model analytes were obtained. PALME provided excellent clean-up from the DBS samples, and acceptor solutions were free from phospholipids. Linearity was obtained with r2 > 0.99 for five of the six analytes. Accuracy, precision and UHPLC-MS/MS matrix effects were in accordance with the European Medicines Agency (EMA) guideline. Based on these experiments, PALME shows great potential for future processing of DBS in a short and simple way, and with the presented setup, up to 96 DBS can be processed within a total extraction time of 60 min.

Advanced Electrocardiogram Analysis in the Amitriptyline-poisoned Pig Treated with Activated Charcoal Haemoperfusion.

Coated activated charcoal haemoperfusion (CAC-HP) does not reduce the plasma concentration in amitriptyline (AT)-poisoned pigs. The aim of this non-blinded, randomized, controlled animal trial was to determine if CAC-HP reduces the pathological ECG changes caused by AT poisoning. Fourteen female Danish Landrace pigs (mean weight 27.7 kg, range 20-35 kg (CAC-HP) and 24.4 kg, range 18-30 kg (control group, CG), n = 7 in each group) were included. After randomization, the pigs were anaesthetized and intravenously poisoned with AT. The intervention group underwent 4 hr of CAC-HP plus standard care (oral activated charcoal). Intervention was compared to standard care alone. From each pig, a 12-lead ECG and haemodynamic variables were obtained at baseline, at full AT loading dose, before and during CAC-HP. Baseline ECG variables (RR, PR, QRS, QTc, QTp, QTe, TpTe and TpTe/QT) for lead II, v2 and v5 were not significantly different (F = 0.035-0.297, p-values 0.421-0.919). Differences within groups over time and between groups were tested by anova repeated measures. For all variables, the time-plus-group level of significance revealed a p-value > 0.05. Severe cardiovascular arrhythmias occurred in both groups with 3 in the CAC-HP group versus 1 incident with premature death in the CG. The attenuating effect of CAC-HP to orally instilled activated charcoal alone on AT-induced ECG alterations did not differ significantly. We conclude that the use of modern CAC-HP as an adjunctive treatment modality in AT-poisoned pigs is inadequate.

Magnetic micro-solid-phase extraction based on magnetite-MCM-41 with gas chromatography-mass spectrometry for the determination of antidepressant drugs in biological fluids.

A new facile magnetic micro-solid-phase extraction coupled to gas chromatography and mass spectrometry detection was developed for the extraction and determination of selected antidepressant drugs in biological fluids using magnetite-MCM-41 as adsorbent. The synthesized sorbent was characterized by several spectroscopic techniques. The maximum extraction efficiency for extraction of 500 µg/L antidepressant drugs from aqueous solution was obtained with 15 mg of magnetite-MCM-41 at pH 12. The analyte was desorbed using 100 µL of acetonitrile prior to gas chromatography determination. This method was rapid in which the adsorption procedure was completed in 60 s. Under the optimized conditions using 15 mL of antidepressant drugs sample, the calibration curve showed good linearity in the range of 0.05-500 µg/L (r2  = 0.996-0.999). Good limits of detection (0.008-0.010 µg/L) were obtained for the analytes with good relative standard deviations of <8.0% (n = 5) for the determination of 0.1, 5.0, and 500.0 µg/L of antidepressant drugs. This method was successfully applied to the determination of amitriptyline and chlorpromazine in plasma and urine samples. The recoveries of spiked plasma and urine samples were in the range of 86.1-115.4%. Results indicate that magnetite micro-solid-phase extraction with gas chromatography and mass spectrometry is a convenient, fast, and economical method for the extraction and determination of amitriptyline and chlorpromazine in biological samples.