The metabolism of 1-phenyl-2-(N-methyl-N-benzylamino)propane (benzphetamine) and 1-phenyl-2-(N-methyl-N-furfurylamino)propane (furfenorex) in man

Sewer epidemiology mass balances for assessing the illicit use of methamphetamine, amphetamine and tetrahydrocannabinol

In sewer epidemiology, mass balances are used to back-extrapolate measurements of wastewater influent concentrations of appropriate drug residues to assess the parent illicit drug's level of use in upstream populations. This study focussed on developing and refining mass balances for the use of illicit methamphetamine, amphetamine and tetrahydrocannabinol. As a first step, a multi-criteria evaluation was used to select unchanged methamphetamine, unchanged amphetamine and 11-nor-9-carboxy-tetrahydrocannabinol as the most appropriate drug residues to track a selected population's use of illicit methamphetamine, amphetamine and tetrahydrocannabinol, respectively. For each of these selected drug residues, mass balances were developed by utilizing all disposition data available for their release from all their respective sources, incorporating route-of-administration considerations where relevant, and accounting for variations in the metabolic capacity of users of the various relevant licit and illicit sources. Further, since the selected drug residues for the use of methamphetamine and amphetamine cannot only result from their use but numerous other licit and illicit sources, comprehensive general source models were developed for their enantiomeric-specific release to sewers. The relative importance of the sources identified in the general source model was evaluated by performing national substance flow analyses for a number of countries. Results suggested that licit sources of methamphetamine are expected to be only of significance in populations where its illicit use is minor. Similarly, in populations where the use of illicitly produced amphetamine is currently of relevance, licit contributions to the sewer loads of amphetamine are likely to be of negligible importance. Lastly, the study of tetrahydrocannabinol back-extrapolation mass balances suggested that further research is required to assess the importance of fecal elimination of 11-nor-9-carboxy-tetrahydrocannabinol.

Molecular modeling of human cytochrome P450 2W1 and its interactions with substrates

The human cytochrome P450 2W1 (CYP2W1) was categorized into the so-called "orphan" CYPs because of its unknown enzymatic function. However, recent studies showed that the recombinant CYP2W1 exhibited broad catalytic activity towards several chemicals. Furthermore, this enzyme was selectively expressed in some forms of cancers, whereas a very low expression was found in human normal issues. These render CYP2W1 as a potential drug target for cancer therapy. At present, however, little information is available on the active site topology and the substrate binding modes of CYP2W1. In this study, the three-dimensional model of CYP2W1 was constructed using the homology modeling method. Two known substrates, benzphetamine and indole, were then docked into the active site, and refined by molecular dynamics simulations. The interaction energy between the substrates and the enzyme was calculated and analyzed by using the MM-GBSA method. The results indicated that the constructed CYP2W1 model can account for the regioselectivity of this enzyme towards the known substrates and van der Waals interactions were the driving force for the substrate binding. Several key residues were identified to be responsible for the binding of indole and benzphetamine with CYP2W1. These findings provide useful information for the detailed characterization of the biological roles of CYP2W1 and structure-based drug design of this enzyme.

Simultaneous determination of amphetamine and methamphetamine enantiomers in urine by simultaneous liquid–liquid extraction and diastereomeric derivatization followed by gas chromatographic–isotope dilution mass spectrometry

A simple, rapid, reliable, and economic analytical scheme starting with in situ liquid-liquid extraction and asymmetric (or diastereomeric) chemical derivatization (ChD) followed by gas chromatography (GC)-isotope dilution mass spectrometry (MS) is described for the simultaneous determination of D- and L-amphetamine (AP) and methamphetamine (MA) in urine which could have resulted from the administration of various forms of questioned amphetamines or amphetamines-generating drugs. By using L-N-trifluoroacetyl-1-prolyl chloride (L-TPC) as chiral derivatizing agent, resolutions of 2.2 and 2.0 were achieved for the separation of AP and MA enantiomeric pairs, respectively, on an ordinary HP-5MS capillary column. The GC-MS quantitation was carried out in the selected ion monitoring (SIM) mode using m/z 237 and 251 as the quantifier ions for the respective diastereomeric pairs of AP-L-TPC and MA-L-TPC. The calibration curves plotted for the two pairs of analytes stretch with good linearity down to 45 ng/mL, and the limits of detection and quantitation determined were as low as 40 and 45 ng/mL, respectively. Also, a comparative study using 10 real-case urine specimens previously screened as positive for MA administration showed mostly tolerable biases between the two sums (of concentration) of D- and L-MA obtained via an asymmetric L-TPC-ChD approach and via an ordinary pentafluoropropionylation (PFPA-ChD) approach, respectively, as well as between the two sums of D- and L-AP obtained thereupon, thus validating the proposed analytical scheme as a promising forensic protocol for the detailed analysis of enantiomeric amphetamines in urine.

Clinical pharmacokinetics of amfetamine and related substances: monitoring in conventional and non-conventional matrices

Consumption of amfetamine-type stimulants, including classical amfetamines and 'designer drugs', has been recognised as one of the most significant trends in drug abuse at the end of the past century and at the beginning of the current one. The first cause is the increasing consumption amongst youth of methylenedioxy- and methoxy-substituted amfetamines, of which the pharmacology in humans is currently under investigation. Secondly, the abuse of more classical amfetamines, such as amfetamine itself and metamfetamine, continues to be highly prevalent in some geographical regions. Amfetamines are powerful psychostimulants, producing increased alertness, wakefulness, insomnia, energy and self-confidence in association with decreased fatigue and appetite as well as enhanced mood, well-being and euphoria. From a clinical pharmacokinetic perspective, amfetamine-type stimulants are rather homogeneous. Their oral bioavailability is good, with a high distribution volume (4 L/kg) and low binding to plasma proteins (less than 20%). The elimination half-life is 6-12 hours. Both hepatic and renal clearance contribute to their elimination from the body. Hepatic metabolism is extensive in most cases, but a significant percentage of the drug always remains unaltered. Amfetamine and related compounds are weak bases, with a pKa around 9.9, and a relatively low molecular weight. These characteristics allow amfetamine-type stimulants to diffuse easily across cell membranes and lipid layers and to those tissues or biological substrates with a more acidic pH than blood, facilitating their detection in alternative matrices at relatively high concentrations. In most cases, the concentrations found are higher than expected from the Henderson-Hasselbach equation. Drug monitoring in non-conventional biological matrices (e.g. saliva, hair, nails, sweat) has recently gained much attention because of its possible applications in clinical and forensic toxicology. An individual's past history of medication, compliance or drug abuse can be obtained from testing of hair and nails, whereas data on current status of drug use can be provided by analysis of sweat and saliva. Because of the physicochemical properties of amfetamine-type stimulants, this group of drugs is one of the most suitable for drug testing in non-conventional matrices.

Preparation of immunoaffinity columns for direct enantiomeric separation of amphetamine and/or methamphetamine

Immunoaffinity chromatographic columns were prepared for direct enantiomeric determination of racemic methamphetamine and amphetamine in this study. The stationary phase was synthesized by covalently bonding an anti-D-methamphetamine monoclonal antibody onto a pre-activated support (e.g. silica, sepharose 4B). Chromatographic results revealed that the immunoaffinity columns achieved enantiomeric separation of racemic amphetamine and methamphetamine. The immunoaffinity columns also have the ability to directly extract D-methamphetamine from urine by changing the pH of the mobile phase, this ability making it practical for the columns to determine a very low concentration of D-methamphetamine in urine.

Precursor medications as a source of methamphetamine and/or amphetamine positive drug testing results

Medical Review Officer interpretation of laboratory results is an important component of drug testing programs. The clinical evaluation of laboratory results to assess the possibility of appropriate medical use of a drug is a task with many different facets, depending on the drug class considered. This intercession prevents the reporting of positive results unless it is apparent that drugs were used illicitly. In addition to the commonly encountered prescribed drugs that yield positive drug testing results, other sources of positive results must be considered. This review describes a series of compounds referred to as "precursor" drugs that are metabolized by the body to amphetamine and/or methamphetamine. These compounds lead to positive results for amphetamines even though neither amphetamine nor methamphetamine were used, a possibility that must be considered in the review of laboratory results. Description of the drugs, their clinical indications, and results seen following administration are provided. This information allows for the informed evaluation of results with regard to the potential involvement of these drugs.

Analysis of benzphetamine and its metabolites in rat urine by liquid chromatography-electrospray ionization mass spectrometry

An analytical method to identify and determine benzphetamine (BMA) and its five metabolites in urine was developed by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) using the solid-phase extraction column Bond Elut SCX. Deuterium-labeled compounds, used as internal standards, were separated chromatographically from each corresponding unlabeled compound in the alkaline mobile phase with an alkaline-resistant ODS column. This method was applied to the identification and determination of BMA and its metabolites in rat urine collected after oral administration of BMA. Under the selected ion monitoring mode, the limit of quantitation (signal-to-noise ratio 10) for BMA, N-benzylamphetamine (BAM), p-hydroxybenzphetamine (p-HBMA), p-hydroxy-N-benzylamphetamine (p-HBAM), methamphetamine (MA) and amphetamine (AM) was 700 pg, 300 pg, 500 pg, 1.4 ng, 6 ng and 10 ng in 1 ml of urine, respectively. This analytical method for p-HBMA, structurally closer to the unchanged drug of all the metabolites, was very sensitive, making this a viable metabolite for discriminating the ingestion of BMA longer than the parent drug or other metabolites in rat.

Simultaneous determination of dimethylamphetamine and its metabolites in rat hair by gas chromatography-mass spectrometry

In order to study the disposition of dimethylamphetamine (DMAP) and its metabolites, DMAP N-oxide, methamphetamine (MA) and amphetamine (AP), from plasma to hair in rats, a simultaneous determination method for these compounds in biological samples using gas chromatography-mass spectrometry with selected ion monitoring (GC-MS-SIM) was developed. As DMAP N-oxide partially degrades to DMAP and MA during GC-MS analysis, it was necessary to avoid conditions which co-extract the N-oxide in the sample preparation so as to assure no contribution of artifactual products from DMAP N-oxide in the detection of the other compounds. For confirmation of the satisfactory separation of DMAP N-oxide from the others, the internal standards used for quantification were labeled with different numbers of deuterium atoms. Determination of unchanged DMAP was performed without any derivatization, that of DMAP N-oxide was carried out after conversion into trifluoroacetyl-MA by reaction with trifluoroacetic anhydride, and MA and AP were quantified after trifluoroacetyl-derivatization. After intraperitoneal administration of DMAP HCI to pigmented hairy rats (5 mgkg(-1) day(-1), 10 days, n=3), concentrations of DMAP and its metabolites in urine, plasma and hair were measured by GC-MS-SIM. The area under the concentration versus time curves (AUCs) of DMAP, DMAP N-oxide, MA and AP in the plasma were 397.2+/-97.5, 279.7+/-68.3, 18.4+/-1.2 and 15.9+/-2.2 microg min ml(-1), while their concentrations in the hair newly grown for 4 weeks after administration were 4.82+/-0.67. 0.45+/-0.09, 3.25+/-0.36 and 0.89+/-0.05 ng mg(-1), respectively. This fact suggested that the incorporation tendency of DMAP N-oxide from plasma into hair was distinctly low in comparison with the other compounds.

Illegal or legitimate use? Precursor compounds to amphetamine and methamphetamine

The interpretation of methamphetamine and amphetamine positive test results in biological samples is a challenge to clinical and forensic toxicology for several reasons. The effects of pH and dilution of urine samples and the knowledge about legitimate and illicit sources have to be taken into account. Besides a potentially legal prescription of amphetamines, many substances metabolize to methamphetamine or amphetamine in the body: amphetaminil, benzphetamine, clobenzorex, deprenyl, dimethylamphetamine, ethylamphetamine, famprofazone, fencamine, fenethylline, fenproporex, furfenorex, mefenorex, mesocarb, and prenylamine. Especially the knowledge of potential origins of methamphetamine and amphetamine turns out to be very important to prevent a misinterpretation of the surrounding circumstances and to prove illegal drug abuse. In this review, potential precursor compounds are described, including their medical use and major clinical effects and their metabolic profiles, as well as some clues which help to identify the sources.

Development of a method for the quantitation of benzphetamine metabolites in human urine by high-performance liquid chromatography

We developed a high-performance liquid chromatography (HPLC) method for quantitating p-hydroxy-N-benzylamphetamine glucuronide (pHBAG) and p-hydroxy-benzphetamine glucuronide (pHBZG), which are urinary metabolites of benzphetamine, in humans. Urine samples were hydrolysed with beta-glucuronidase (EC 3.2.1.31) at 37 degrees C overnight and the treated urine was applied to a solid phase extraction column. After washing the column with water, 0.01 mol/L acetic acid and methanol, pHBA and pHBZ were eluted with dichloromethane:isopropanol:28% ammonium hydroxide (78.4:19.6:2.0 v/v). The eluate was evaporated and the residue was dissolved in acetonitrile: 5 mmol/L 1-pentane sulphonic acid (5:95 v/v) and analysed by HPLC with gradient elution. The amounts of urinary pHBAG and pHBZG excreted by two human subjects after oral administration of 10 mg benzphetamine hydrochloride were determined. About 10-15% of benzphetamine was found to be excreted as pHBAG and pHBZG, and almost all of these metabolites were excreted within 24 h. Urine samples should be collected as early as possible after ingestion of benzphetamine to detect pHBAG and pHBZG.

Current research and case work activities of criminalistics in Japan

The current research and case work activities of criminalistics in Japan are described. The selected forensic science disciplines are forensic osteology including specialized technology of skull identification, forensic serology, forensic DNA analysis of poisonous materials, forensic hair and fiber analysis, trace evidence analysis, document analysis, forensic psychology mainly concerned with the so-called lie-detector, forensic image analysis, voice print analysis, fire and explosion analysis, forensic engineering, firearm and toolmark analysis. The current activity of the Training Institute of Forensic Science at the National Research Institute of Police Science is also briefly described with special regard to the education and training course of forensic DNA typing analysis. Instruments for analytical and methodological use are listed according to the availability in evidence sample analyses.

Direct high-performance liquid chromatographic and high-performance liquid chromatographic-thermospray-mass spectrometric determination of enantiomers of methamphetamine and its main metabolites amphetamine and p-hydroxymethamphetamine in human urine

For the identification of drug abuse, a simple and rapid method which allows us to distinguish enantiomers of methamphetamine (MA) and its metabolites amphetamine (AP) and p-hydroxymethamphetamine (p-OHMA) in human urine was explored by coupling direct HPLC and HPLC-thermospray-mass spectrometry (HPLC-TSP-MS) both of which employ a beta-cyclodextrin phenylcarbamate-bonded silica column. HPLC analysis was performed after the solid-phase extraction from the urine sample with Bond Elut SCX, and D- and L-enantiomers of MA, AP and p-OHMA could be separated well. The proposed conditions are as follows: eluent, acetonitrile-methanol-50 mM potassium phosphate buffer (pH 6.0) (10:30:60, v/v) flow-rate, 1.0 ml/min temperature, 25 degrees C. The linear calibration curves were obtained for D- and L- MA and AP in the concentration range from 0.2 to 20 micrograms/ml; the relative standard deviation for D- and L-AP and D- and, L-MA ranged from 1.67 to 2.35% at 2 micrograms/ml and the detection limits were 50 ng/ml for D- and L-AP and D-MA and 100 ng/ml for L-MA. For the verification of the direct HPLC identification, HPLC-TSP-MS was also carried out under the same conditions except that acetonitrile-methanol-100 mM ammonium acetate (pH 6.0) (10:30:60, v/v) was used as an eluent. Upon applying the scan mode, 10 ng/ml for D- and L-AP and D-MA and 20 ng/ml for L-MA were the detection limits. Using the selected ion monitoring mode, 0.5 ng/ml, 0.8 ng/ml and 1 ng/ml could be detected for D- and L-AP, D-MA and L-MA, respectively.

Abuse of smoking methamphetamine mixed with tobacco. III. Urinary metabolites of N-cyanomethylmethamphetamine, a pyrolysis product formed by smoking methamphetamine in tobacco, and species difference in its metabolism between rat and mouse

1. N-cyanomethylmethamphetamine (CMMA) or methamphetamine (MA) was given intraperitoneally to rat and mouse (1, 3, 10 mg/kg). The basic urinary metabolites of CMMA were determined by mass spectrometry (MS) and compared with those of MA. 2. N-formylmethamphetamine (FMA), a specific metabolite of CMMA, was found in both rat and mouse urine. However, the dose percentage of FMA excreted in mouse urine was less than one-quarter of that in rat urine. 3. No CMMA was detected in rat or mouse urine collected within 72 h after dosing. All other basic metabolites of CMMA except FMA, i.e. MA, amphetamine (AP), p-hydroxymethamphetamine (OHMA) and p-hydroxyamphetamine (OHAP), were the same as those of MA in both species. 4. The excretion pattern of the urinary metabolites of CMMA was similar to that of MA except FMA in both species, though the amount of each metabolite of MA administration was larger than that of CMMA administration. However, in urinary excretion of FMA and hydroxylated metabolites, definite species differences were observed between rat and mouse. 5. A trace amount of FMA was identified in the urine of an abuser who had smoked MA with tobacco.

The metabolism of dimethylamphetamine in rat and man

1. Urinary metabolites of dimethylamphetamine after oral administration to rat and healthy human volunteers have been studied. 2. Six metabolites and unchanged drug were detected in rat urine and the same metabolites except p-hydroxyamphetamine were found in human urine. The major metabolite was dimethylamphetamine N-oxide in both cases, and methamphetamine and amphetamine were also excreted as minor metabolites. 3. Metabolites excreted in three days after administration of the drug to rat amounted to about 57% of the dose and those after administration to man, 53-56%.