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.

A green and low-cost method employing switchable hydrophilicity solvent for the simultaneous determination of antidepressants in human urine by gas chromatography - mass spectrometry detection.

In this study, the use of switchable hydrophilicity solvent with a simple and low-cost lab-made device for the extraction procedure in homogeneous liquid-liquid microextraction is proposed for the first time in the determination of antidepressants in human urine. The antidepressants studied consisted of fluoxetine, amitriptyline, nortriptyline, imipramine, desipramine and sertraline. The optimization of the main parameters that can influence on the extraction efficiency was performed through multivariate approaches. The analytes were separated and identified by gas chromatography coupled to mass spectrometry (GC-MS). The optimal extraction conditions consisted of using N,N-dimethylcyclohexylamine (DMCHA) as the switchable hydrophilicity solvent (SHS), 500 µL of urine sample previously diluted with ultrapure water at 1:1 ratio (v/v), 200 µL of a mixture of SHS:HCl 6 mol L-1 (1:1 v/v), 600 µL of NaOH 10 mol L-1 and 3 min of extraction time. A volume of 40 µL of diphenylamine at concentration of 500 µg L-1 (20 ng) was used as internal standard. The method developed was in-house validated, providing coefficients of determination higher than 0.995 for all analytes, limits of detection (LOD) from 0.02 to 0.88 µg L-1, limits of quantification (LOQ) from 0.05 to 2.92 µg L-1, relative recoveries of 68 to 102%, intra-day precision from 0.5 to 15.9%, inter-day precision from 4.2 to 19.3%, selectivity and robustness. The method proposed was successfully applied in five human urine samples from a Toxicological Information Center located in Porto Alegre (Brazil). The results demonstrated that the µP-SHS-HLLME approach is highly cost-effective, rapid, simple and environmentally-friendly with satisfactory analytical performance.

Supramolecular microextraction combined with paper spray ionization mass spectrometry for sensitive determination of tricyclic antidepressants in urine.

This work describes a novel methodology to analyze four tricyclic antidepressants (amitriptyline, doxepin, imipramine and, nortriptyline) in urine samples by combining supramolecular microextraction and paper spray ionization mass spectrometry (PS-MS). The proposed method uses a supramolecular solvent in which reverse micelles of 1-decanol are dispersed in tetrahydrofuran (THF)/water. The extraction of the tricyclic antidepressants at pH 9.0 requires a sample volume of 10.0 mL, short extraction time (1.0 min of extraction and 5 min of centrifugation), low amounts of organic solvent (50 µL of 1-decanol and 200 µL of THF), and provides high preconcentration factors: 96.9 to amitriptyline, 93.6 to doxepin, 71.3 to imipramine, and 146.9 to nortriptyline. The quantification by PS-MS is fast and straightforward because chromatographic separation is not required and all analytes were determined simultaneously. The limits of detection (LOD), quantification (LOQ), and the precision (RSD, %) of the developed method ranged between 5.2 and 8.6 µg L-1, 17.4-28.7 µg L-1 and 1.3-12.9%, respectively. Urine samples of five individuals (three males and two females) were used for accuracy evaluation. The accuracy obtained in these spiked urine samples at µg L-1 levels varied from 95.3 to 112.0%. The method also provided clean mass spectra with a high signal-to-noise ratio, which demonstrates the analytical appeal combination of supramolecular microextraction with determination by paper spray mass spectrometry.

Storage of urine specimens in point of care (POC) urine drug testing cups reduces concentrations of many drugs.

BACKGROUND: Many clinical toxicology laboratories receive urine specimens in urine cups that contain point of care (POC) drug testing strips. We conducted this study to evaluate the effect on the stability of commonly measured drugs in the clinical toxicology laboratory when urine is exposed to POC urine drug testing cups. METHODS: Drug free urine was spiked with 85 drugs that were measured by a validated liquid chromatography mass spectrometry (LCMS) method after exposure to POC urine drug testing cups at ambient and 2-6 °C temperatures. Alterations ≥20% were defined as significant changes in the drugs concentration. RESULTS: Concentrations of amitriptyline, cyclobenzaprine, fentanyl, fluoxetine, flunitrazepam, nortriptyline, paroxetine, and sertraline were significantly reduced when urine specimens were stored inside POC urine drug testing cups for 24 h at ambient temperature. Storage of urine in urine chemistry dipsticks reduced the concentration of several drugs. When spiked urine was exposed to an increasing number of POC urine drug testing strips, the concentrations of some drugs were reduced in a dose-dependent manner. The drugs that were absorbed by POC urine drug testing strips were partially back extracted from the strips. CONCLUSION: Exposure of urine specimens to POC urine drug testing strips reduces the concentration of several drugs measured by LCMS method.

Pharmacokinetic determination and analysis of nortriptyline based on GC-MS coupled with hollow-fiber drop-to-drop solvent microextraction technique.

AIM: A simple, sensitive and robust technique of hollow-fiber drop-to-drop solvent microextraction coupled with GC-MS has been successfully developed for the detection of antidepressant drug nortriptyline in human blood and urine samples. The recoveries of the drug from the spiked samples are found to be well within the range and appropriate to support the method. RESULTS: The LOD for the drug was obtained to be 0.007, 0.009 and 0.021 µg ml-1 in deionized water, urine and blood samples of human subjects, respectively. Linearity was obtained over the concentration range of 0.5-5.0 mg l-1 in deionized water with correlation coefficient 0.99672.

Direct Analysis of Free Aqueous and Organic Operational Solutions as a Tool for Understanding Fundamental Principles of Electromembrane Extraction.

Aqueous and organic phases in microelectromembrane extraction (µ-EME) were formed as adjacent plugs of free immiscible solutions in narrow-bore polymeric tubing, and each single phase was recovered and analyzed after µ-EME. A three-phase µ-EME setup was employed for investigation of time-dependent distribution of model basic drugs among aqueous and organic phases. Exact concentrations of nortriptyline and papaverine in donor solution, acceptor solution, and free liquid membrane (FLM) were determined by capillary electrophoresis with ultraviolet detection (CE-UV). At typical µ-EME conditions (acceptor, 1 µL of 25 mM HCl; FLM, 1 µL of 4-nitrocumene; donor, 1 µL of basic drugs in 10 mM HCl; and extraction potential, 250 V), experimentally determined distribution of the drugs confirmed the kinetic model for electrically mediated transfer of charged analytes. Rapid depletion of the drugs from donor solution (0-180 s) and rapid saturation of FLM with the drugs (15-60 s) were followed by gradual transfer of the drugs across FLM and gradual liberation into acceptor solution (30-240 s). Exhaustive transfer of the drugs from donor to acceptor solution was obtained in 15 min. A good correlation between the analytes' distribution and µ-EME electric currents was observed; the currents increased during drugs' transfer across FLM, were concentration dependent, and demonstrated transfer of the drugs across FLM in their ionized forms. Proper understanding of the fundamental principles of µ-EME transfer enabled further fine-tuning of the µ-EME process. Transfer of the drugs across FLM was controlled by optimizing the composition and pH of acceptor solution, and quantitative fractionation of nortriptyline into aqueous acceptor (96%) and of papaverine into organic FLM (95%) was achieved based on their different pKa values. µ-EME fractionation of the two drugs was compatible with raw human urine and excellent repeatability (RSD ≤ 3.9%), linearity (r2 ≥ 0.9989), and limits of detection (≤ 0.15 µg/mL) were achieved for µ-EME-CE-UV of the drugs in standard solutions and urine samples.

Dynamic electromembrane extraction: Automated movement of donor and acceptor phases to improve extraction efficiency.

In the present research, dynamic electromembrane extraction (DEME) was introduced for the first time for extraction and determination of ionizable species from different biological matrices. The setup proposed for DEME provides an efficient, stable, and reproducible method to increase extraction efficiency. This setup consists of a piece of hollow fiber mounted inside a glass flow cell by means of two plastics connector tubes. In this dynamic system, an organic solvent is impregnated into the pores of hollow fiber as supported liquid membrane (SLM); an aqueous acceptor solution is repeatedly pumped into the lumen of hollow fiber by a syringe pump whereas a peristaltic pump is used to move sample solution around the mounted hollow fiber into the flow cell. Two platinum electrodes connected to a power supply are used during extractions which are located into the lumen of the hollow fiber and glass flow cell, respectively. The method was applied for extraction of amitriptyline (AMI) and nortriptyline (NOR) as model analytes from biological fluids. Effective parameters on DEME of the model analytes were investigated and optimized. Under optimized conditions, the calibration curves were linear in the range of 2.0-100µgL(-1) with coefficient of determination (r(2)) more than 0.9902 for both of the analytes. The relative standard deviations (RSD %) were less than 8.4% based on four replicate measurements. LODs less than 1.0µgL(-1) were obtained for both AMI and NOR. The preconcentration factors higher than 83-fold were obtained for the extraction of AMI and NOR in various biological samples.

[The determination of amitriptyline and its metabolite, nortriptyline, in the biological objects of the corpse by the high-performance liquid chromatography technique].

Tricyclic antidepressants are among the preparations that most frequently cause intoxication in adults and children; moreover, poisoning with these substances not infrequently has a fatal outcome. Medications belonging to this group, such as amitriptyline, are extensively used to manage manifestations of depression, anxiety, migraine, neuropathic pain, and hyperactivity syndrome. Amitriptyline overdosage causes non-specific symptoms of intoxication, and its clinical picture does not allow to identify the nature of a psychotropic xenobiotic. Of primary importance in connection with this is to establish the cause of intoxication or death by the clinical toxicological and forensic medical methods based on the results of the fast identification and quantitation of amitriptyline in biological materials including blood, urine, hepatic tissues, etc. The authors describe the method for the determination of amitriptyline and its principal physiological metabolite nortriptyline in biological objects with the help of high performance liquid chromatography (HPLC).

Tricyclic antidepressants: is your patient taking them? Observations on adherence and unreported use using prescriber-reported medication lists and urine drug testing.

OBJECTIVE: Tricyclic antidepressants (TCAs) are first-line treatment for neuropathic pain. Despite widespread use, many health care providers do not know which patients are currently taking TCAs. The objective of this retrospective data analysis was to determine adherence rates to amitriptyline, nortriptyline, or imipramine. The rate at which patients used TCAs (confirmed by presence of TCA in the urine) but did not inform their health care provider is also reported (non-informed prescriber rate). Finally, the effects of age, sex, and number of prescriptions on adherence and non-informed prescriber rates were assessed. METHODS: Urinary excretion data were obtained from 55,296 patients with pain and were analyzed using liquid chromatography tandem mass spectrometry in a multiplex assay which included amitriptyline, nortriptyline, and imipramine. RESULTS: The adherence rate was 66% (1,407/2,137); the rate of non-informed prescribers was 3% (1,547/55,296) among the general population, and 52% (1,547/2,954) when only TCA users were considered. While adherence was higher among older and female subjects, the number of other medications did not affect adherence rate. CONCLUSIONS: This analysis reveals that many prescribers are not informed when patients start and stop using TCAs.

Liquid-phase microextraction and desorption electrospray ionization mass spectrometry for identification and quantification of basic drugs in human urine.

Hollow fibre liquid-phase microextraction (LPME) and desorption electrospray ionization mass spectrometry (DESI-MS) were evaluated for the identification and quantification of basic drugs in human urine samples. The selective extraction capabilities of three-phase LPME provided a significant reduction in the matrix effects otherwise observed in direct DESI-MS analysis of urine samples. Aqueous LPME extracts (in 10 mM HCl) were deposited on porous Teflon, dried at room temperature, and the dried spots were then analyzed directly with DESI-MS in full scan mode. Pethidine, diphenhydramine, nortriptyline, and methadone were used as model compounds for identification, and their limits of identification were determined to be 100, 25, 100, and 30 ng/mL, respectively. In a reliability test with 19 spiked urine samples, 100% of the positive samples containing the model drugs in concentrations at or above the limit of identification were identified. Diphenhydramine was used as a model compound for quantitative analysis with diphenhydramine-d(5) as an internal standard. The calibration curve was linear in the range 50-2000 ng/mL (R(2) = 0.992) with a limit of quantification at approximately 140 ng/mL. The intra- and inter-day relative standard deviations were <9.5%. In a reliability test with six spiked urine samples, deviations between the measured and the true values for diphenhydramine were in the range 0.2-22.9%.

Liquid-phase microextraction for rapid AP-MALDI and quantitation of nortriptyline in biological matrices.

A liquid-phase microextraction (LPME) method using a micropipette with disposable tips was demonstrated for coupling to atmospheric pressure MALDI-MS (AP-MALDI/MS) as a concentrating probe for rapid analysis and quantitative determination of nortriptyline drug from biological matrices including human urine and human plasma. This technique was named as micropipette extraction (MPE). The best optimized parameters of MPE coupled to AP-MALDI/MS experiments were extraction solvent, toluene; extraction time, 5 min; sample agitation rate, 480 rpm; sample pH, 7; salt concentration, 30%; hole size of micropipette tips, 0.61 mm (id); and matrix concentration, 1000 ppm using alpha-cyano-4-hydroxycinnamic acid (CHCA) as a matrix. Three detection modes of AP-MALDI/MS analysis including full scan, selective ion monitor (SIM), and selective reaction monitor (SRM) of MS/MS were also compared for the MPE performance. The results clearly demonstrated that the MS/MS method provides a wider linear range and lower LODs but poor RSDs than the full scan and SIM methods. The LOD values for the MPE under SIM and MS/MS modes in water, urine, and plasma were 6.26, 47.5, and 94.9 nM, respectively. The enrichment factors (EFs) of this current approach were 36.5-43.0 fold in water. In addition, compared to single drop microextraction (SDME) and LPME using a dual gauge microsyringe with a hollow fiber (LPME-HF) technique, the LODs acquired by the MPE method under MS/MS modes were comparable to those of LPME-HF and SDME but it is more convenient than both methods. The advantages of this novel method are simple, easy to use, low cost, and no contamination between experiments since disposable tips were used for the micropipettes. The MPE has the potential to be widely used in the future because it only requires a simple micropipette to perform all extraction processes. We believe that this technique can be a powerful tool for MALDI/MS analysis of biological samples and clinical applications.

Sample preparation with fiber-in-tube solid-phase microextraction for capillary electrophoretic separation of tricyclic antidepressant drugs in human urine.

Solid-phase microextraction (SPME) is a solvent-free sample preparation technique using a thin coating attached to the surface of a fused silica-fiber as the extraction medium, which has been successfully applied to the analysis of a wide variety of compounds by coupling to gas chromatography (GC). In recent years, in-tube SPME using GC capillary column as the extraction medium has also been developed and coupled with liquid chromatography (LC) for the preconcentration of nonvolatile compounds. In this study, an on-line interface between the fiber-in-tube SPME and capillary electrophoresis (CE) has been developed, and the preconcentration and separation of four tricyclic antidepressant (TCA) drugs, amitriptyline, imipramine, nortriptyline, and desipramine, were performed with the hyphenated system. Under the optimized condition, a better extraction performance than conventional in-tube SPME was obtained, even the length of the extraction medium was much shorter. The results clearly indicated that the fiber was working effectively as an extraction medium. For the separation of these four TCAs, capillary electrophoretic separation with beta-cyclodextrin as the buffer additive has been employed and the application of the developed system to the analysis of complex sample mixtures in a biological matrix is also demonstrated.

Time course of enzyme induction in humans: effect of pentobarbital on nortriptyline metabolism.

To study the effect of induction we gave six male volunteers 10 mg nortriptyline three times a day for 4 weeks and 0.2 gm pentobarbital on days 8 to 21. Plasma and urinary levels of nortriptyline and metabolites were measured. The rate and extent of induction of the enzyme(s) were estimated by a model with use of nortriptyline concentrations. There was a marked decrease of nortriptyline levels after 2 days of pentobarbital treatment. Total clearance of nortriptyline increased more than twofold (range, 1.6-fold to 4.1-fold). Apparent metabolic clearance by 10-hydroxylation increased markedly. The decrease in nortriptyline levels was more rapid than the increase after pentobarbital cessation, fitting with the theory of the model. The induction of nortriptyline metabolism is probably mainly the result of an increase in a non-CYP 2D6 P450 isozyme, possibly CYP 3A4 or a CYP 2C form. More knowledge of induction characteristics of drugs should lead to better predictions of decreased effects and appearance of adverse effects. The kinetic model used for analysis of our data could then be useful.

Possible markers for postmortem drug redistribution.

The possibility that postmortem biochemical changes in blood might parallel drug redistribution and thus serve as markers was explored in a detailed case study. Eighteen blood and 14 tissue and fluid samples were taken at autopsy 16 h after the death of a 34-year-old female from amitriptyline overdose. Ranges of drug concentrations in blood were amitriptyline 1.8 to 20.2 micrograms/mL, nortriptyline 0.6 to 7.3 micrograms/mL, levels were lowest in femoral vein and highest in pulmonary vein blood. Corresponding levels of 17 amino acids showed markedly different patterns of site-to-site variability. There was a strong positive correlation between individual amino acid and drug concentrations in pulmonary blood samples (n = 5), particularly for glycine, leucine, methionine, serine, and valine. In blood samples from the great veins and right heart (n = 10), the correlation was less strong (r = 0.6 to 0.7). Methionine showed a strong positive correlation in pulmonary samples (r = 0.93), and negative correlation in great veing samples (r = -0.68). Lactic acid showed a strong negative correlation in pulmonary samples (r = -0.93) but a positive correlation in great vein samples (r = 0.71). Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, gamma-glutamyl transferase, glucose, and bilirubin had a weak positive correlation with drug levels in great vein samples but not pulmonary samples. The results suggest that hepatic enzymes are relatively poor markers for postmortem hepatic drug shifts but that amino acids, particularly methionine, may be useful markers for pulmonary drug shifts.

Enantioselective amitriptyline metabolism in patients phenotyped for two cytochrome P450 isozymes.

In 26 hospitalized patients with depression, a combined pharmacogenetic test with dextromethorphan, a substrate of cytochrome P450IID6, and mephenytoin, the S-form of which is hydroxylated by a P450IIC isozyme, was carried out before amitriptyline therapy. Metabolites were determined in 24-hour urine samples collected on treatment day 8, and the contributions of individual compounds, including the four isomers of 10-hydroxyamitriptyline and 10-hydroxynortriptyline to total excretion were calculated. Formation of (-)-E-10-hydroxyamitriptyline and (-)-E-10-hydroxynortriptyline apparently depends on the activity of cytochrome P450IID6 because negative correlations existed between the log metabolic ratio of dextromethorphan and the relative quantities of these enantiomers. In contrast, correlations were positive for nortriptyline, (+)-E-10-hydroxynortriptyline, (-)-Z-10-hydroxynortriptyline, and (+)-Z-10-hydroxynortriptyline. The mephenytoin hydroxylase seems to participate in side-chain demethylation to the secondary and primary amines, because the log metabolic ratio of mephenytoin correlated negatively with the relative quantity of E-10-hydroxydidesmethylamitriptyline and positively with that of amitriptyline and its N-glucuronide.

Column switching and high-performance liquid chromatography in the analysis of amitriptyline, nortriptyline and hydroxylated metabolites in human plasma or serum.

A column-switching system for the direct injection of plasma or serum samples, followed by isocratic high-performance liquid chromatography and ultraviolet detection, is described for the simultaneous quantitation of the tricyclic antidepressant amitriptyline, its demethylated metabolite nortriptyline and the E- and Z-isomers of 10-hydroxyamitriptyline and 10-hydroxynortriptyline. The method included adsorption of amitriptyline and metabolites on a reversed-phase C8 clean-up column (10 microns; 20 mm x 4.6 mm I.D.), washing of unwanted material to waste and, after on-line column-switching, separation on a cyanopropyl analytical column (5 microns; 250 mm x 4.6 mm I.D.). The compounds of interest were separated and eluted using acetonitrile-methanol-0.01 M phosphate buffer (pH 6.8) (578:188:235, v/v) within less than 20 min. Various drugs frequently co-administered with amitriptyline or other antidepressants did not interfere with the determinations. In plasma samples spiked with 25-300 ng/ml, the recoveries were between 84 and 112% and the inter-assay coefficients of variation were 3-11%. After a minor modification, as little as 5 ng/ml could be quantitated. There were linear correlations (r greater than 0.99) between drug concentrations of 5-500 ng/ml and the detector signal. The method allows routine measurements of amitriptyline, nortriptyline and hydroxylated metabolites in blood plasma or serum of patients treated with amitriptyline or nortriptyline, and enables the results to be reported within 1 h.

Stereoselective inhibition of nortriptyline hydroxylation in man by quinidine.

1. Four volunteers phenotyped as extensive metabolizers of sparteine took 25 mg nortriptyline hydrochloride and collected urine for 72-80 h. Total free and conjugated 10-hydroxynortriptyline (10-OH-NT) accounted for 54-58% of the dose and it was reduced to 25-40% when 50 mg quinidine sulphate was ingested on the first and second day. 2. Of the four isomers of 10-OH-NT, (-)-E-10-OH-NT was selectively decreased in quantity by quinidine coadministration, while the (+)-isomer and (-)- and (+)-Z-10-OH-NT were found in unchanged or slightly increased quantities. The contribution of (-)-E-10-OH-NT to total E-10-OH-NT and the E-/Z-ratio in total 10-OH-NT were significantly reduced. 3. The quantity of the phenol, 2-hydroxynortriptyline in urine was decreased by quinidine; the relative amounts of metabolites with a primary amino group were not affected. 4. Liver microsomes from a donor in which cytochrome P450IID6 was shown to be present by in vitro phenotyping metabolized NT to E-10-OH-NT containing 86% of the (-)-isomer. Quinidine reduced the hydroxylation rate in (-)-E-10-position much more than that in (+)-E-10-position. 5. Since quinidine selectively impairs the function of cytochrome P450IID6, it is concluded that this isoform catalyses NT hydroxylation predominantly in (-)-E-10- and in 2-position.

Enantioselective hydroxylation of nortriptyline in human liver microsomes, intestinal homogenate, and patients treated with nortriptyline.

The enantioselectivity of hydroxylation of nortriptyline (NT) to E-10-hydroxynortriptyline (E-10-OH-NT) was studied in human liver microsomes, intestinal homogenate, and patients treated with NT. The rate of formation of (-)-E-10-OH-NT was higher than that of (+)-E-10-OH-NT both in the liver microsomes and in the intestinal homogenate. Quinidine, a prototype competitive inhibitor of the cytochrome P450IID6 ("debrisoquin hydroxylase"), inhibited the formation of (-)-E-10-OH-NT in a concentration-dependent manner in liver microsomes, while the formation of (+)-E-10-OH-NT was hardly affected. This indicates that P450IID6 catalyzes the hydroxylation of NT in a highly enantioselective manner to (-)-E-10-OH-NT in the liver. Another P450 isozyme besides IID6 seems to be responsible for the formation of the (+)-enantiomer in the liver. In intestinal homogenate, the formation of both enantiomers of E-10-OH-NT was inhibited to about the same extent by quinidine, the maximum inhibition being much less than in the liver. In the urine of six patients treated with NT, the (-)-enantiomer accounted for 91 +/- 2% of the unconjugated E-10-OH-NT, and for 78 +/- 6% of the glucuronide conjugates. The study shows that NT is hydroxylated in a highly enantioselective way, probably catalyzed by the polymorphic P450IID6, to (-)-E-10-OH-NT both in vitro in human liver as well as in vivo in patients treated with the drug.

[Plasma and urine kinetics of amitriptyline oxide and its metabolites. Comparison of intravenous infusion and oral administration in volunteers]. / Plasma- und Urinkinetik von Amitriptylinoxid und seiner Metaboliten. Vergleich einer intravenösen Infusion mit einer oralen Einmalgabe bei Probanden.

The study objective was to obtain detailed information on the plasma and urine kinetics of amitriptylinoxide (CAS 4317-14-0) and its metabolites. For this reason, 60 mg of amitriptylinoxide was administered to 12 subjects, both by intravenous infusion and by oral dosage, in a study performed according to a randomized two-way cross-over design. In plasma, we succeeded in analyzing the metabolites amitriptyline and nortriptyline in addition to the parent substance amitriptyloxide. The tests for the parent substance amitriptylinoxide revealed maximum plasma levels of 721 and 686 ng/ml at 1.96 h (i.v. infusion) and 0.82 h (oral formulation), respectively. Mean values of 2331 (infusion) and 1714 h.ng/ml (oral formulation) were determined for the area under the curve from time 0 to infinity AUC (0-infinity). We also produced a comprehensive evaluation of amitriptyline, however, this was not possible for the metabolite nortriptyline. In urine, we succeeded in a reliable quantification of 4 metabolites, namely cis-OH-amitriptylinoxide, trans-OH-amitriptylinoxide, amitriptyline and OH-nortriptyline, in addition to the parent substance amitriptylinoxide. In individual samples, nortriptyline, cis-OH-amitriptyline and trans-OH-amitriptyline were additionally identified. In the course of the study, there were no reports or observations of any adverse reactions in addition to the side effects known for amitriptylinoxide from literature. There were no clinically relevant differences in tolerability observed between these two preparations.

Use of the EMITtox serum tricyclic antidepressant assay for the analysis of urine samples.

The EMITtox serum tricyclic antidepressant (TCA) assay is intended for use with serum or plasma. Currently, there are no commercially available immunoassay kits available for the detection of TCAs in urine. The proposed method utilizes the EMITtox serum TCA assay for the direct analysis of urine samples. The minimum detectable concentration of nortriptyline in urine is 25 ng/mL. The within-run CV was determined to be 0.6% and the between-run CV was 2.6%. The TCA assay cross-reacts with phenothiazines and antihistamines. The proposed methodology should be applicable to other EMIT serum assays to allow their use with urine.