Characterization and tentative identification of new flunitrazepam metabolites in authentic human urine specimens using liquid chromatography-Q exactive-HF hybrid quadrupole-Orbitrap-mass spectrometry (LC-QE-HF-MS).

Flunitrazepam (FNZ) is a potent hypnotic, sedative, and amnestic drug used to treat severe insomnia. In our recent study, FNZ metabolic profiles were investigated carefully. Six authentic human urine samples were purified using solid phase extraction (SPE) without enzymatic hydrolysis, and urine extracts were then analyzed by liquid chromatography-Q exactive-HF hybrid quadrupole-Orbitrap-mass spectrometry (LC-QE-HF-MS), using the full scan positive ion mode and targeted MS/MS (ddms2) technique to make accurate mass measurements. There were 25 metabolites, including 13 phase I and 12 phase II metabolites, which were detected and tentatively identified by LC-QE-HF-MS. In addition, nine previously unreported phase II glucuronide conjugates and four phase I metabolites are reported here for the first time. Eight metabolic pathways, including N-reduction and O-reduction, N-glucuronidation, O-glucuronidation, mono-hydroxylation and di-hydroxylation, demethylation, acetylation, and combinations, were implicated in this work, and 2-O-reduction together with dihydroxylation were two novel metabolic pathways for FNZ that were identified tentatively. Although 7-amino FNZ is widely considered to be the primary metabolite, a previously unreported metabolites (M12) can also serve as a potential biomarker for FNZ misuse.

Withdrawn: Hair Analysis for Drug-Facilitated Crime: The Critical Role of Hair Growth Rate.

Hair analysis is increasingly used in detecting drug-facilitated crime (DFC) claiming success in identifying even single dose exposures. The calculation of accurate deposition time of the drug in hair is typically based on the assumption of mean hair growth of 1 cm/month. We describe a case of potential exposure to flunitrazepam. Assuming the literature average hair growth rate of 1 cm/month, the alleged victim had measurable amounts of the 7 amino flunitrazepam a month after the alleged drug exposure. However, in this case, due to hair dying, the true growth rate could be quantified at 1.5 cm/month. This difference has led to different interpretation from the one based on the average assumed hair growth of 1 cm/month. In conclusion, hair growth rate can be a critical variable in verifying the alleged time of drug exposure.

Quantification of 7-aminoflunitrazepam in human urine by polymeric monolith-based capillary liquid chromatography coupled to tandem mass spectrometry.

Using a simple liquid-liquid extraction (LLE) procedure for sample pretreatment, 7-Aminoflunitrazepam (7-aminoFM2), a major metabolite of flunitrazepam (FM2), was determined in urine samples by polymeric monolith-based capillary liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The linearity was found in the range of 0.1-50ngmL-1 with a method detection limit (signal-to-noise ratio of 3) estimated at 0.05ngmL-1. Using the proposed method, good precision and recovery were also found in spiked urine samples at the levels of 0.5, 5.0, and 50ngmL-1 (intra-day/inter-day precision: 0.6-1.8% / 0.1-0.8%; post-spiked/pre-spiked recovery: 95.4-102.9% / 96.3-102.5%). In addition, acceptable relative differences (-24.2 - 0.8%) were observed by analyzing clinical urine samples using this monolith-based capillary LC-MS/MS method compared with the results obtained by the routine GC-MC method. Using the monolithic column, no noticeable deterioration of separation efficiency or carry-over was observed for more than 200 injections of urine samples. The applicability of the developed monolith-based capillary LC-MS/MS method was demonstrated by quantifying 7-aminoFM2 in various clinical urine samples. Based on these experimental results, the proposed LLE-monolith-based capillary LC-MS/MS method shows the potential for routine determination of drug metabolites in human urine for clinical and forensic applications.

Postmortem distribution of flunitrazepam and its metabolite 7-aminoflunitrazepam in body fluids and solid tissues in an autopsy case: Usefulness of bile for their detection.

We experienced an autopsy case of a woman in her 70s, in which the direct cause of her death was judged as asphyxia due to the occlusion of food in the trachea. The postmortem interval was estimated at about 2days. The specimens dealt with were femoral vein blood, right heart blood, left heart blood, bile, brain, lung, heart muscle, liver, spleen, kidney, pancreas, skeletal muscle, and adipose tissue. By tentative drug screening, we found a high concentration of 7-aminoflunitrazepam in the femoral vein blood, which lead us to examine the postmortem distribution of flunitrazepam and its metabolite 7-aminoflunitrazepam in her body fluids and solid tissues. The extraction of flunitrazepam, 7-aminoflunitrazepam and internal standard nimetazepam was performed by a modified QuEChERS method, followed by the analysis by liquid chromatography-tandem mass spectrometry. Because this study included various kinds of human matrices with quite different properties, we used the standard additional method to overcome the matrix effects. The concentration of 7-aminoflunitrazepam were generally much higher than those of the parent drug flunitrazepam for most specimens except for the adipose tissue, showing that flunitrazepam is readily metabolized to its 7-amino metabolite after absorption into the body both antemortem and postmortem. The outstandingly highest concentration of 7-animoflunitrazepam was found in the bile, followed by the kidney, pancreas, left heart blood, spleen and liver. Although a majority of flunitrazepam was converted to 7-aminoflunitrazepam, the flunitrazepam concentration was highest in the pancreas, followed by the spleen, bile, left heart blood, and brain. In contrast to the results on synthetic cannabinoids, the levels of flunitrazepam and 7-animoflunitrazepam in the adipose tissue were relatively low. The present study showed that the bile may be a useful specimen for detection of unchanged benzodiazepines/their metabolites to be collected at autopsy.

Identification and quantification of 35 psychotropic drugs and metabolites in hair by LC-MS/MS: application in forensic toxicology.

Despite a non-invasive sampling, hair samples are generally collected in limited amounts for an obvious esthetic reason. In order to reduce the required quantity of samples, a multianalytes method allowing simultaneous identification and quantification of 35 psychoactive drugs was developed. After incubation of 50 mg of hair in a phosphate buffer pH 5 for one night at room temperature, the substances of interest were extracted by a simple liquid-liquid extraction step, with a dichloromethane/ether mixture (70:30, v/v). After evaporation under a gentle stream of nitrogen and reconstitution in formate buffer (2 mM, pH 3)/acetonitrile (90:10, v/v), twenty microliter were injected into the LC-MS/MS system for a chromatographic run of 29 min using an Atlantis T3 column (150 × 2.1 mm, 3 µm) (Waters Corp, Milford, USA) and a gradient mixture of 2 mM, pH 3.0 ammonium formate, and 2 mM, pH 3.0 ammonium formate/acetonitrile. The data acquisition was performed in scheduled MRM mode. Intra- and inter-day precisions, estimated using the coefficient of variation and relative bias, were lower than 20 % for all concentration levels, except for two compounds. The limits of detection and quantification ranged from 0.5 to 10 pg/mg. After complete validation, this method has been successfully used in several forensic cases, three of which are reported.

Comprehensive automation of the solid phase extraction gas chromatographic mass spectrometric analysis (SPE-GC/MS) of opioids, cocaine, and metabolites from serum and other matrices.

The analysis of opioids, cocaine, and metabolites from blood serum is a routine task in forensic laboratories. Commonly, the employed methods include many manual or partly automated steps like protein precipitation, dilution, solid phase extraction, evaporation, and derivatization preceding a gas chromatography (GC)/mass spectrometry (MS) or liquid chromatography (LC)/MS analysis. In this study, a comprehensively automated method was developed from a validated, partly automated routine method. This was possible by replicating method parameters on the automated system. Only marginal optimization of parameters was necessary. The automation relying on an x-y-z robot after manual protein precipitation includes the solid phase extraction, evaporation of the eluate, derivatization (silylation with N-methyl-N-trimethylsilyltrifluoroacetamide, MSTFA), and injection into a GC/MS. A quantitative analysis of almost 170 authentic serum samples and more than 50 authentic samples of other matrices like urine, different tissues, and heart blood on cocaine, benzoylecgonine, methadone, morphine, codeine, 6-monoacetylmorphine, dihydrocodeine, and 7-aminoflunitrazepam was conducted with both methods proving that the analytical results are equivalent even near the limits of quantification (low ng/ml range). To our best knowledge, this application is the first one reported in the literature employing this sample preparation system.

A rapid UPLC-MS/MS method for simultaneous determination of flunitrazepam, 7-aminoflunitrazepam, methadone and EDDP in human, rat and rabbit plasma.

A simple, high-throughput, sensitive LC-ESI-MS/MS method is presented for the simultaneous determination of methadone (MET), flunitrazepam (FNZ) and their major metabolites, EDDP (2-ethilidene-1,5-dimethyl-3,3-diphenylpyrrolidone) and 7-aminoflunitrazepam (7-AFNZ), respectively, in human, rat and rabbit plasma. The isolation of the selected compounds involved a liquid-liquid extraction with ethyl acetate at a basic pH. Good chromatographic separation was achieved on a HSS T3 column (1.8 µm particle size), with a 3 min gradient elution using a mixture of acetonitrile with 0.1% formic acid (solvent A) and 5mM ammonium acetate (solvent B) as the mobile phase. The tandem mass spectrometric detection was performed in multiple reaction monitoring (MRM) mode with ionization of the analytes in positive mode. The assay was fully validated according to current acceptance criteria for bioanalytical methods validation. It was proved to be linear in the range of 0.5-250 ng/mL, with adequate accuracy and precision over this range. Based on accuracy and CV% values the LOQ and ULOQ values were set at 0.509 ng/mL and 2036 ng/mL for MET, 0.520 ng/mL and 2080 ng/mL for EDDP, 0.524 ng/mL and 2096 ng/mL for FNZ and 0.528 ng/mL and 2114 ng/mL for 7-AFNZ, respectively. The method was tested for potential matrix effects, without observing significant ion suppression. The investigated compounds stability was examined in plasma at room temperature and after three freeze-thaw cycles and in the final extract when maintained at 4 °C in the autosampler. Potential stability issues were observed only for FNZ at room temperature. The method was successfully applied to quantify the selected compounds in human, rat and rabbit plasma samples, after exposure to FNZ or simultaneous exposure to FNZ and MET.

Simultaneous analysis of some club drugs in whole blood using solid phase extraction and gas chromatography-mass spectrometry.

The use of psychoactive substances to improve social relations and increase body energy, in Rave Culture, has raised many legal and health public concerns, both for illicit trade and consumption. Therefore, forensic toxicology plays an important role in this area, mainly linked to the detection and quantitation of these substances, both in vivo and in post-mortem samples. In fact, at the moment, forensic sciences have been under public authorities' scrutiny and critical look, due to the increasing attention of the media and public opinion, always applying for the use of scientific knowledge to help solving forensic cases. However, forensic toxicology results are only reliable to solve legal cases if all the analytical methodologies used are appropriately validated. In this work, a methodology for the extraction and analysis of 7-aminoflunitrazepam, buprenorphine, flunitrazepam, ketamine, methadone, phencyclidine (PCP) and d-propoxyphene was developed for whole blood samples, with solid phase extraction (SPE), using OASIS(®) MCX SPE columns, and gas chromatography coupled to mass spectrometry. The procedure presented here proved to be reliable, specific, selective and sensitive, with good LODs and LOQs and good precision.The adoption of a SPE procedure with an automatic SPE extraction device, allowed an increased level of automation in sample treatment, being contemporarily less time-consuming, increasing productiveness, and allowing good recovery and appropriate selectivity being, also, simple and reproducible. The simultaneous detection and quantitation of all compounds by the same extraction and detection methodology is crucial and has a great potential for forensic toxicology and clinical analysis.

Acute intoxication caused by overdose of flunitrazepam and triazolam: high concentration of metabolites detected at autopsy examination.

A 52-year-old woman was found dead on the floor of the living room on the first floor of a house, which belonged to the man with whom she shared the house. On visiting the site, her clothes were found to be undisturbed. Packages of flunitrazepam (Silece, 2 mg/tablet) and triazolam (Halcion, 0.25 mg/tablet) were found strewn around the victim. Toxicological analysis was performed, and the concentrations of flunitrazepam, triazolam, and their metabolites in the victim's blood and urine were measured by high-performance liquid chromatography coupled with photodiode array and mass spectrometry. A high blood concentration of 7-aminoflunitrazepam was detected (1,270 ng/g), and further metabolites such as 7-acetamidoflunitrazepam, 7-acetamidodesmethylflunitrazepam, and 7-aminodesmethylflunitrazepam were detected in the blood and urine samples. In addition, 4-hydroxytriazolam and α-hydroxytriazolam were detected in her urine at a concentration of 950 and 12,100 ng/mL, respectively.On the basis of the autopsy findings and toxicology results of high concentrations of both flunitrazepam and triazolam derivatives, the cause of death was determined to be acute intoxication from flunitrazepam and triazolam.

Segmental hair analysis can demonstrate external contamination in postmortem cases.

Excluding laboratory mistakes, a false positive hair result can be observed in case of contamination from environmental pollution (external contamination) or after drug incorporation into the hair from the individual body fluids, such as sweat or putrefactive fluid (post mortem artifact). From our 20 years experience of hair testing, it appears that artifact(s) cannot be excluded in some post mortem cases, despite a decontamination procedure. As a consequence, interpretation of the results is a challenge that deserves particular attention. Our strategy will be reviewed in this paper, based on six cases. In all cases, a decontamination procedure with two washes of 5 ml of dichloromethane for 5 min was performed and the last dichloromethane wash was negative for each target drug. From the histories, there was no suspicion of chronic drug use. In all six cases, the concentrations detected were similar along the hair shaft, irrespective of the tested segment. We have considered this as indicative of external contamination and suggested to the forces or the judges that it is not possible to indicate exposure before death. In contrast to smoke, it seems that contamination due to aqueous matrices (sweat, putrefactive fluid, blood) is much more difficult to remove. To explain potential incorporation of 7-aminoflunitrazepam via putrefactive material, the author incubated negative hair strands in blood spiked at 100 ng/ml and stored at +4°C, room temperature and +40 °C for 7, 14 and 28 days. After routine decontamination, 7-aminoflunitrazepam tested positive in hair, irrespective of the incubation temperature, as early as after 7 days (233-401 pg/mg). In all periods, maximum concentrations were observed after incubation at room temperature. The highest concentration (742 pg/mg) was observed after 28 days incubation at room temperature. It is concluded that a standard decontamination procedure is not able to completely remove external contamination in case of post mortem specimens. Homogenous segmental analyses can be probably indicative of external contamination and therefore a single hair result should not be used to discriminate long-term exposure to a drug. Nor should the presence of a metabolite be considered as a discrimination tool, as it can also be present in putrefactive material.

Nanoparticle-assisted MALDI-TOF MS combined with seed-layer surface preparation for quantification of small molecules.

Despite the advantages of simplicity and high-throughput detection that matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has over other methods, quantitative analysis of low-molecular-weight analyte is hampered by interference from matrix-derived background noise and signal fluctuation due to the inhomogeneous MALDI sample surface. Taking advantage of improved sample homogeneity through matrix-conjugated magnetic nanoparticles (matrix@MNP) and the seed-layer method, we report a new strategy for the rapid identification and quantification of drugs in urine samples, using morphine and 7-aminoflunitrazepam (7-aminoFM2) as model compounds. To our knowledge, this is the first attempt using the seed-layer method for small molecule analysis. By applying the proposed seed-layer method, which was specifically optimized for the 2,5-dihydroxybenzoic acid@MNP (DHB@MNP) matrix, homogeneous sample crystallization examined by microscopy analysis was obtained that generated reproducible MALDI signals (RSD<10.0%). For urine sample analysis, simple liquid-liquid extraction as a sample pretreatment step effectively reduced the ion suppression effect caused by the endogenous components in urine; good recoveries (82-90%) were obtained with a small ion suppression effect (<14% of signal decrease). This newly developed method demonstrated good quantitation linearity over a range of 50-2000 ng mL(-1) (R(2)>0.996) with reduced signal variation (RSD<10.0%). The detection limit is 30 ng mL(-1) with good precision (intra-day, 2.0-9.3%; inter-day, 5.0-10.0%) and accuracy (intra-day, 95.0-106.0%; inter-day, 103.0-115.5%). The nanoparticle-assisted MALDI-TOF MS combined with seed-layer surface preparation provides a rapid, efficient and accurate platform for the quantification of small molecules in urine samples.

Characterization and evaluation of two-dimensional microfluidic chip-HPLC coupled to tandem mass spectrometry for quantitative analysis of 7-aminoflunitrazepam in human urine.

Microfluidic chip-based high-performance-liquid-chromatography coupled to mass spectrometry (chip-HPLC-MS) has been widely used in proteomic research due to its enhanced sensitivity. We employed a chip-HPLC-MS system for determining small molecules such as drug metabolites in biological fluids. This chip-HPLC-MS system integrates a microfluidic switch, a 2-dimensional column design including an enrichment column (160 nL) for sample pre-concentration and an analytical column for chromatographic separation, as well as a nanospray emitter on a single polyimide chip. In this study, a relatively large sample volume (500 nL) was injected into the enrichment column for pre-concentration and an additional 4 µL of the initial mobile phase was applied to remove un-retained components from the sample matrix prior to chromatographic separation. The 2-dimensional column design provides the advantages of online sample concentration and reducing matrix influence on MS detection. 7-Aminoflunitrazepam (7-aminoFM2), a major metabolite of flunitrazepam (FM2), was determined in urine samples using the integrated chip-HPLC-MS system. The linear range was 0.1-10 ng mL(-1) and the method detection limit (signal-to-noise ratio of 3) was 0.05 ng mL(-1) for 7-aminoFM2. After consecutive liquid-liquid extraction (LLE) and solid-phase extraction (SPE), the chip-HPLC-MS exhibited high correlation between 7-aminoFM2 spiked Milli-Q water and 7-aminoFM2 spiked urine samples. This system also showed good precision (n = 5) and recovery for spiked urine samples at the levels of 0.1, 1.0, and 10 ng mL(-1). Intra-day and inter-day precision were 2.0-7.1% and 4.3-6.0%, respectively. Clinical urine samples were also analyzed by this chip-HPLC-MS system and acceptable relative differences (-1.3 to -13.0%) compared with the results using a GC-MC method were determined. Due to its high sensitivity and ease of operation, the chip-HPLC-MS system can be utilized for the determination of small molecules such as drug metabolites and neurotransmitters in biological fluids for clinical diagnosis.

Simultaneous determination and quantification of 12 benzodiazepines in serum or whole blood using UPLC/MS/MS.

The benzodiazepines are a large, commonly prescribed family of psychoactive drugs. We describe a method permitting the simultaneous detection and quantification of 12 benzodiazepines in serum using ultra-performance liquid chromatography (UPLC) coupled with tandem mass spectrometry (MS/MS). Analytes included alprazolam, temazepam, oxazepam, nordiazepam, clonazepam, lorazepam, diazepam, chlordiazepoxide, midazolam, flunitrazepam, 7-aminoclonazepam, and 7-aminoflunitrazepam. Sample pretreatment is simple consisting of protein precipitation using cold acetonitrile (ACN) mixed with the deuterated internal standards. Samples were capped and vortexed for 5 min to ensure maximum precipitation. Following a 5-min centrifugation period, 400 microL of the supernatant was transferred to a clean tube and evaporated down under nitrogen. Samples were reconstituted in 200 microL of a deionized water:ACN (80:20) mixture and transferred to appropriate vials for analysis. Chromatographic run time was 7.5 min, and the 12 analytes were quantified using multiple reaction monitoring (MRM) and 6-point calibration curves constructed for each analyte at concentrations covering a clinically significant range.

Urinary detection times and excretion patterns of flunitrazepam and its metabolites after a single oral dose.

We investigated the excretion profiles of flunitrazepam metabolites in urine after a single dose. Sixteen volunteers received either 0.5 or 2.0 mg flunitrazepam. Urine samples were collected after 2, 4, 6, 8, 12, 24, 48, 72, 96, 120, 240, and 336 h. Samples were screened using CEDIA (300 microg/L cutoff) and quantitated using liquid chromatography-tandem mass spectrometry. The cutoff was 0.5 microg/L for flunitrazepam, N-desmethylflunitrazepam, 7-aminoflunitrazepam, 7-aminodesmethylflunitrazepam, 7-acetamidoflunitrazepam, and 7-acetamidodesmethylflunitrazepam. None of the subjects receiving 0.5 mg were screened positive, and only 23 of 102 samples from the subjects given 2.0 mg were positive with CEDIA. The predominant metabolites were 7-aminoflunitrazepam and 7-aminodesmethylflunitrazepam. For all subjects given the low dose, 7-aminoflunitrazepam was detected up to 120 h, and for two subjects for more than 240 h. Seven subjects given the high dose were positive up to 240 h for 7-aminoflunitrazepam. We conclude that the ratio 7-aminodesmethylflunitrazepam to 7-aminoflunitrazepam increased with time, independent of dose, and may be used to estimate the time of intake. For some low-dose subjects, the metabolite concentrations in the early samples were low and a chromatographic method may fail to detect the intake. We think laboratories should consider this when advising police and hospitals about sampling as well as when they set up strategies for analysis.

Determination of 7-aminoflunitrazepam in urine by dispersive liquid-liquid microextraction with liquid chromatography-electrospray-tandem mass spectrometry.

Dispersive liquid-liquid microextraction (DLLME) and liquid chromatography-electrospray-tandem mass spectrometry (LC-ES-MS/MS) procedure was presented for the extraction and determination of 7-aminoflunitrazepam (7-aminoFM2), a biomarker of the hypnotic flunitrazepam (FM2) in urine sample. The method was based on the formation of tiny droplets of an organic extractant in the sample solution using water-immiscible organic solvent [dichloromethane (DCM), an extractant] dissolved in water-miscible organic dispersive solvent [isopropyl alcohol (IPA)]. First, 7-aminoFM2 from basified urine sample was extracted into the dispersed DCM droplets. The extracting organic phase was separated by centrifuging and the sedimented phase was transferred into a 300 microl vial insert and evaporated to dryness. The residue was reconstituted in 30 microl mobile phase (20:80, acetonitrile:water). An aliquot of 20 microl as injected into LC-ES-MS/MS. Various parameters affecting the extraction efficiency (type and volume of extraction and dispersive solvent, effect of alkali and salt) were evaluated. Under optimum conditions, precision, linearity (correlation coefficient, r(2)=0.988 over the concentration range of 0.05-2.5 ng/ml), detection limit (0.025 ng/ml) and enrichment factor (20) had been obtained. To our knowledge, DLLME was applied to urine sample for the first time.

The detection of various opiates and benzodiazepines by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry.

A technique using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOFMS) is applied to qualitative and quantitative drug testing. Human serum was 'spiked' with known quantities of benzodiazepines and a 'street heroin' mixture including some of the major metabolites and impurities. The sample components were extracted from the matrix by solid-phase extraction (SPE). Constituents containing polar hydroxyl and/or secondary amine groups were derivatised with N-methyl-N-(tert-butyldimethyl)trifluoroacetamide (MTBSTFA) to improve the chromatographic performance. An orthogonal separation of the matrix constituents was achieved by coupling a DB-5ms (5% phenyl) to a BPX50 (50% phenyl) GC column. The eluant was focused onto the second column by a twin-stage cryo-modulator. Rapid 6 s modulation times were achieved by transfer from a 30 m x 0.25 mm (length x internal diameter) to a 2 m x 0.1 mm column. TOFMS with rapid spectral acquisition (< or =500 spectra/s) was employed in the mass range m/z 40-650. A clean mass spectrum was obtained for each analyte using mass spectral deconvolution software. The sensitivity and repeatability of the method were evaluated by the preparation of calibration standards for two benzodiazepines, flunitrazepam and its major metabolite 7-aminoflunitrazepam (7-amino-FN), in the concentration range 5-1000 ng/mL. The limits of detection (LODs) and limits of quantitation (LOQs), calculated by repeat injections (x10) of the lowest standard, were 1.6 and 5.4 ng/mL (flunitrazepam); 2.5 and 8.5 ng/mL (7-amino-FN), respectively. There is scope to extend this protocol to screen a large number of drugs and metabolites stored in a library database.

Buprenorphine alters desmethylflunitrazepam disposition and flunitrazepam toxicity in rats.

High-dosage buprenorphine (BUP) consumed concomitantly with benzodiazepines (BZDs) including flunitrazepam (FZ) may cause life-threatening respiratory depression despite a BUP ceiling effect and BZDs' limited effects on ventilation. However, the mechanism of BUP/FZ interaction remains unknown. We hypothesized that BUP may alter the disposition of FZ active metabolites in vivo, contributing to respiratory toxicity. Plasma FZ, desmethylflunitrazepam (DMFZ), and 7-aminoflunitrazepam (7-AFZ) concentrations were measured using gas chromatography-mass spectrometry. Intravenous BUP 30 mg/kg pretreatment did not alter plasma FZ and 7-AFZ kinetics in Sprague-Dawley rats infused with 40 mg/kg FZ over 30 min, whereas resulting in a three-fold increase in the area under the curve (AUC) of DMFZ concentrations compared with control (p < 0.01). In contrast, BUP did not significantly modify plasma DMFZ concentrations after intravenous infusion of 7 mg/kg DMFZ, whereas resulting in a similar peak concentration to that generated from 40 mg/kg FZ administration. Regarding the effects on ventilation, BUP (30 mg/kg) as well as its combination with FZ (0.3 mg/kg) significantly increased PaCO(2), whereas only BUP/FZ combination decreased PaO(2) (p < 0.001). Interestingly, FZ (40 mg/kg) but not DMFZ (40 mg/kg) significantly increased PaCO(2) (p < 0.05), whereas DMFZ but not FZ decreased PaO(2) (p < 0.05). Thus, decrease in PaO(2) appears related to BUP-mediated effects on DMFZ disposition, although increases in PaCO(2) relate to direct BUP/FZ additive or synergistic dynamic interactions. We conclude that combined high-dosage BUP and FZ is responsible for increased respiratory toxicity in which BUP-mediated alteration in DMFZ disposition may play a significant role.

Long-term stability of various drugs and metabolites in urine, and preventive measures against their decomposition with special attention to filtration sterilization.

The long-term stability of drugs and metabolites of forensic interest in urine, and preventive measures against their decomposition have been investigated, with special attention to filtration sterilization. An aseptic urine collection kit, which was recently developed based on filtration sterilization, was utilized for the aseptic collection and storage of urine samples. For evaluating preservation measures, methamphetamine (MA), amphetamine (AP), nitrazepam (NZ), estazolam (EZ), 7-aminoflunitrazepam (7AF), cocaine (COC), and 6-acetylmorphine (6AM) were spiked into urine at 500 ng/mL each, and were monitored for 6 months at 25, 4, and -20 degrees C, after the addition of NaN(3) and/or filtration sterilization using the aseptic collection kit. In severely contaminated urine with bacteria, there were significant losses of 7AF and NZ, and slight decomposition of MA and AP at 25 degrees C. However, such degradation was successfully suppressed by the use of the kit, though the use of the kit and NaN(3) were preferred for 7AF. The kit was also effective in preventing the hydrolyses of COC and 6AM, while it was suggested that the common preservative NaN(3) can accelerate the hydrolysis of such ester-type drugs and metabolites.

Sweeping technique combined with micellar electrokinetic chromatography for the simultaneous determination of flunitrazepam and its major metabolites.

A sweeping technique, in conjunction with micellar electrokinetic chromatography, for the simultaneous determination of flunitrazepam and its major metabolites, 7-aminoflunitrazepam and N-desmethylflunitrazepam, is described. The optimized conditions for the sweeping and separation were a pH 9.5 buffer, 25mM borate, 50mM cetyltrimethylammonium bromide, 30% MeOH (v/v), and a 151-mm injection length. The calibration functions were all linear with the coefficient of determination (r(2)) exceeding 0.996 for the three target compounds. Using the sweeping procedure, the limits of detection were determined to be 13.4, 5.6, and 12.0ng/mL for flunitrazepam, 7-aminoflunitrazepam, and N-desmethylflunitrazepam, respectively, and the sensitivity enhancement for each compound was within the range of 110-200 fold. The RSDs for the retention time and the peak area were less than 4.10%. The optimized sweeping method was also used to examine a spiked urine sample. We conclude that sweeping with micellar electrokinetic chromatography has considerable potential use in clinical and forensic analyses of flunitrazepam and its metabolites.