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Purpose N-tert-Butoxycarbonylmethamphetamine (BocMA), a masked derivative of methamphetamine (MA), converts into MA under acidic condition and potentially acts as a precursor to MA following ingestion. To investigate the metabolism and excretion of BocMA, metabolism tests were conducted using human liver microsomes (HLM), rat liver microsomes (RLM) and rat. Methods BocMA metabolites were analyzed after 1000-ng/mL BocMA incubation with microsomes for 3, 8, 13, 20, 30, and 60 min. Rats were administered intraperitoneal injections (20 mg/kg) of BocMA and their urine was collected in intervals for 72 h. Metabolites were detected by liquid chromatography–tandem mass spectrometry with five authentic standards. Results Several metabolites including 4-hydroxy-BocMA, N-tert-butoxycarbonylephedrine and N-tert-butoxycarbonyl-cathinone were detected for HLM and RLM. In the administration test, three glucuronides of hydroxylated metabolites were detected. The total recovery values of BocMA and the metabolites during the first 72 h accounted for only 0.3% of the administered dose. Throughout the microsomal and administration experiments, MAs were not detected. Conclusion Hydroxylation, carbonylation and N-demethylation were proposed as metabolic pathways. However, BocMA and phase I metabolites were hardly detected in urine. This study provides useful information to interpret the possibility of BocMA intake as the cause of MA detection in biological sample.

In order to investigate the incorporation behavior of drugs into hair in early stage (within 24 h) after intake, time-course changes in drug distribution in black hair were carefully analyzed after a single oral administration of methoxyphenamine (MOP), a non-regulated analog of methamphetamine. Single-hair specimens collected by plucking with the roots intact at appropriate intervals post-intake were each divided into 1-mm segments from the proximal end, and MOP in each segment was determined by a validated liquid chromatography–tandem mass spectrometry procedure. At 10 min after intake, MOP was not detected in any of the segments. MOP became detectable 30 min after intake in the hair bulb (0–1-mm segment from the proximal end) and 1 h after intake in the upper dermis zone (1–2-mm to 4–5-mm segments). The amount of MOP in the hair bulb increased rapidly over 3 h after intake and reached a maximum concentration of ∼100–900 pg/1-mm single hair (11–95 ng/mg) around 3–10 h after intake, whereas that in the upper dermis zone increased at a more gradual pace over 24 h and reached a plateau at ∼30–100 pg/1-mm hair (3–11 ng/mg). These differences can be attributed to the different incorporation mechanisms of the drug. Results from this study can further elucidate the drug incorporation mechanism, which is crucial for accurately interpreting results in hair analyses. Our findings also suggest that hair drug analysis with special attention to the hair root can serve as a useful complementary approach to urine- and blood-based testing in the field of forensic toxicology.

Various cathinone-derived designer drugs (CATs) have recently appeared on the drug market. This study examined the mechanism for the generation of dehydrated ions for CATs during electrospray ionization collision-induced dissociation (ESI-CID). The generation mechanism of dehydrated ions is dependent on the amine classification in the cathinone skeleton, which is used in the identification of CATs. The two hydrogen atoms eliminated during the dehydration of cathinone (primary amine) and methcathinone (secondary amine) were determined, and the reaction mechanism was elucidated through the deuterium labeling experiments. The hydrogen atom bonded to the amine nitrogen was eliminated with the proton added during ESI, in both of the tested compounds. This provided evidence that CATs with tertiary amine structures (such as dimethylcathinone and α-pyrrolidinophenones [α-PPs]) do not undergo dehydration. However, it was shown that the two major tertiary amine metabolites (1-OH and 2″-oxo) of CATs generate dehydrated ions in ESI-CID. The dehydration mechanisms of the metabolites of α-pyrrolidinobutiophenone (α-PBP) belongs to α-PPs were also investigated. Stable-isotope labeling showed the dehydration of the 1-OH metabolite following a simple mechanism where the hydroxy group was eliminated together with the proton added during ESI. In contrast, the dehydration mechanism of the 2″-oxo metabolite involved hydrogen atoms in three or more locations along with the carbonyl group oxygen, indicating that dehydration occurred via multiple mechanisms likely including the rearrangement reaction of hydrogen atoms. These findings presented herein indicate that the dehydrated ions in ESI-CID can be used for the structural identification of CATs.

The influence of lipophilicity and functional groups of synthetic cannabinoids (SCs) on their blood concentrations and urinary excretion has been studied by analyzing blood and urine specimens sampled from drivers who were involved in a car crashes under the influence of SCs. A total of 58 specimens (26 urine and 31 blood specimens), sampled within 13h of the occurrence, were analyzed by liquid chromatography-tandem mass spectrometry. Fifteen SCs were detected in those specimens; the SCs detected were categorized as follows: Class 1, Naphthoyl/Benzoyl indole (EAM2201 and three other analogs); Class 2, Indole-3-carboxylate/carboxamide containing naphthol/quinol (5F-PB-22 and four other analogs); and Class 3, Indazole-3-carboxamide containing valine/tert-leucine derivative (5F-AMB and five other analogs). The calculated lipophilicity index log P, the octanol/water participation coefficient, of those SCs in Classes 1, 2, and 3 ranged between 5.01-8.14, 5.80-6.74 and 2.29-3.81, respectively. Class 3 SCs were detectable in 12 out of 13 urine specimens, but those in Classes 1 and 2 were not detected in urine. Our analytical results indicated that the boundary line for their detectability in urine lies between log P 4 and 5. The blood concentrations of Class 3 SCs varied widely (0.0036-31ng/ml) depending on their log P, while much smaller variation was observed among those in Class 2 (0.10-5.0ng/ml).

In order to investigate the influence of pigmentation on the incorporation of drugs into hair, time-course changes in drug distribution along non-pigmented (white) hairs as well as pigmented (black) hairs plucked from the same subject was observed following single administrations of two basic drugs with different properties, zolpidem and methoxyphenamine. These drugs in 1-mm sections of single hair specimens were each determined by a liquid chromatography–tandem mass spectrometric procedure. During the early stage (12–36 h) after intake, for black hairs, both drugs were detected over the entire area of hair root (4–5 mm in length), in which notable concentration of these drugs in the hair bulb (0–1-mm segment from the bottom of hair root, Region 1) and lower concentrations in the upper dermis zone (1–2-mm to 3–4-mm or to 4–5-mm segments, Region 2) were commonly observed. Meanwhile, for white hairs, high drug concentrations in Region 1 as detected in black hairs were not observed although only small amounts of these drugs were detected over Region 2. Subsequent time-course changes in the concentration of drugs in hair demonstrated that the drugs once incorporated into white hair via Region 2 decreased gradually over the period from 24 h to 35 days after intake, but those of black hairs remained almost unchanged. These findings revealed here suggest that hair pigments have two important roles in the distribution of drugs: (1) incorporation of drugs into hair via Region 1, and (2) retention of already incorporated drugs in the hair tissue. These findings would be useful for discussing individual drug-use history based on hair analysis in the forensic fields.

Recently, thienyl derivatives of cathinones have appeared on the market as new psychoactive substances (NPS). In this study, identification and characterization of 2-(pyrrolidin-1-yl)-1-(thiophen-2-yl)pentan-1-one (α-PVT), 2-(pyrrolidin-1-yl)-1-(thiophen-2-yl)butan-1-one (α-PBT), and their bromothienyl analogs disclosed in illicit products are described. In our analysis, some analogous compounds of α-PVT, which had a bromine substitution on the thiophene ring, were identified in the samples containing α-PVT; 1-(4-bromothiophen-2-yl)-2-(pyrrolidin-1-yl)pentan-1-one, 1-(5-bromothiophen-2-yl)-2-(pyrrolidin-1-yl)pentan-1-one, and 1-(4,5-dibromothiophen-2-yl)-2-(pyrrolidin-1-yl)pentan-1-one by comparing the analytical data with synthetic reference standards. We also observed 1-(4-bromothiophen-2-yl)-2-(pyrrolidin-1-yl)butan-1-one and 1-(5-bromothiophen-2-yl)-2-(pyrrolidin-1-yl)butan-1-one from a powder product, in which α-PBT was detected. The brominated α-PVTs were also found when overbrominated 1-(thiophen-2-yl)pentan-1-one reacted with pyrrolidine, and they are suspected to be the by-products of α-PVT synthesis. In Japan, cathinone derivatives with a phenyl group as the aromatic ring have been widely controlled by generic scheduling. To escape from such a regulation, analogs with different aromatic groups such as α-PVT and α-PBT appeared on the illicit market of psychoactive compounds. To our knowledge, this is the first report describing identification of α-PBT, and bromothienyl analogs of both α-PVT and α-PBT in illicit drug products. The synthetic method and analytical data shown in this study will be useful for identification of the thienyl derivatives of cathinone analogs.

1-Phenyl-2-(pyrrolidin-1-yl)octan-1-one (PV9) and 16 metabolites, including diastereomers and conjugates, were identified or tentatively detected in human urine by gas chromatography–mass spectrometry and liquid chromatography–high-resolution tandem mass spectrometry. These urinary metabolites indicated that the metabolic pathways of PV9 include: (1) the reduction of ketone groups to their corresponding alcohols; (2) oxidation of the pyrrolidine ring to the corresponding pyrrolidone; (3) aliphatic oxidation of the terminal carbon atom to the corresponding carboxylate form, possibly through an alcohol intermediate (not detected); and (4) hydroxylation at the penultimate carbon atom to the corresponding alcohols followed by further oxidation to ketones, and combinations of these steps. In addition, results from the quantitative analyses of five phase-I metabolites using newly synthesized authentic standards suggested that the main metabolic pathway includes the aliphatic oxidation of terminal and/or penultimate carbons. Human metabolism of PV9 differed significantly from those of α-pyrrolidinovalerophenone and α-pyrrolidinobutiophenone, suggesting that the main metabolic pathways of α-pyrrolidinophenones significantly change depending on the alkyl chain length of the parent molecule.

Urinary metabolites of α-pyrrolidinovalerophenone (α-PVP) in humans were investigated by analyzing urine specimens obtained from abusers. Unambiguous identification and accurate quantification of major metabolites were realized using gas chromatography–mass spectrometry and liquid chromatography-tandem mass spectrometry with newly synthesized authentic standards. Two major metabolic pathways were revealed: (1) the reduction of the β-keto moiety to 1-phenyl-2-(pyrrolidin-1-yl)pentan-1-ol (OH-α-PVP, diastereomers) partly followed by conjugation to its glucuronide, and (2) the oxidation at the 2″-position of the pyrrolidine ring to α-(2″-oxo-pyrrolidino)valerophenone (2″-oxo-α-PVP) via the putative intermediate α-(2″-hydroxypyrrolidino)valerophenone (2″-OH-α-PVP). Of the metabolites retaining the structural characteristics of the parent drug, OH-α-PVP was most abundant in most of the specimens examined.

Cathinone-derived designer drugs have recently grown to be popular as drugs of abuse. 3,4-Dimethylmethcathinone (DMMC) has recently been abused as one of the alternatives to controlled cathinones. In the present study, DMMC and its major metabolites, 3,4-dimethylcathinone (DMC), 1-(3,4-dimethylphenyl)-2-methylaminopropan-1-ol (β-OH-DMMC, diastereomers), and 2-amino-1-(3,4-dimethylphenyl)propan-1-ol (β-OH-DMC, diastereomers), have been identified and quantified in a DMMC user’s urine by gas chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry using newly synthesized authentic standards. Other putative metabolites including oxidative metabolites of the xylyl group and conjugated metabolites have also been detected in urine. The identified and putative phase I metabolites indicated that the metabolic pathways of DMMC include its reduction of the ketone group to the corresponding alcohols, N-demethylation to the primary amine, oxidation of the xylyl group to the corresponding alcohol and carboxylate forms, and combination of these steps. Concentrations of the identified metabolites were found to increase slightly after enzymatic hydrolysis, suggesting that these compounds are partially metabolized to the respective conjugates.

In order to investigate the incorporation of drugs into hair, matrix-assisted laser desorption/ionization-time-of-flight tandem mass spectrometry (MS/MS) imaging was performed on the longitudinal sections of single scalp hair shafts sampled from volunteers after a single oral administration of methoxyphenamine (MOP), a noncontrolled analogue of methamphetamine. Hair specimens were collected by plucking out with the roots intact, and these specimens were prepped by an optimized procedure based on freeze-sectioning to detect the drug inside the hair shaft and hair root. Time-course changes in the imaging results, with confirmatory quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis for each 1-mm segment of single hair strands, revealed a substantial concentration of the drug first onto the hair bulbs after ingestion, while only a small portion appeared to be incorporated into the hair matrix, forming a 2-3 mm distinctive drug band with tailing. Comparable amount of the drug also appeared to be incorporated into the keratinized hair shaft in the upper dermis zone, forming another distinct drug band of about 2 mm, which both moved toward the distal side, following the strand's growth rate. These findings provide forensically crucial information: there are two major drug incorporation sites, at least for MOP, which cause overlap of the recordings and deteriorates its chronological resolution down to about 11 days or perhaps longer.

Urinary phase I metabolites of α-pyrrolidinobutiophenone (α-PBP) in humans were investigated by analyzing urine specimens obtained from drug abusers. Unequivocal identification and accurate quantification of major metabolites were realized using gas chromatography–mass spectrometry and liquid chromatography–tandem mass spectrometry with newly synthesized authentic standards. Two major phase I metabolic pathways were revealed: (1) reduction of the ketone group to 1-phenyl-2-(pyrrolidin-1-yl)butan-1-ol (OH-α-PBP, diastereomers) partly followed by conjugation to its glucuronide and (2) oxidation at the 2″-position of the pyrrolidine ring to α-(2″-oxo-pyrrolidino)butiophenone (2″-oxo-α-PBP) via the putative intermediate α-(2″-hydroxypyrrolidino)butiophenone (2″-OH-α-PBP). Of the phase I metabolites retaining the structural characteristics of the parent drug, OH-α-PBP was the most abundant in all specimens examined. Comparison of the phase I metabolism of α-PBP and α-pyrrolidinovalerophenone (α-PVP) suggested a relationship between the aliphatic side chain length and the metabolic pathways in α-pyrrolidinophenones: the shorter aliphatic side chain (1) led to more extensive metabolism via reduction of the ketone group than via the oxidation at the 2″-position of the pyrrolidine ring and (2) influenced the isomeric ratio of a pair of diastereomers.

A rapid and convenient extraction method has been developed for the determination of various drugs and metabolites of forensic interest in blood by modifying the dispersive solid-phase extraction method "QuEChERS". The following 13 analytes with various chemical properties were used for the method development and its validation: amphetamine, methamphetamine, zolpidem, the carboxylate-form major metabolite of zolpidem M-1, flunitrazepam, 7-aminoflunitrazepam, phenobarbital, triazolam, α-hydroxytriazolam, brotizolam, α-hydroxybrotizolam, chlorpromazine, and promethazine. The modification of the QuEChERS method includes the use of relatively large amounts of inorganic salts in order to coagulate blood, which allows easy isolation of the organic extract phase. A combination of 100 mg anhydrous magnesium sulfate as a dehydrating agent, 50mg sodium chloride as a salting-out agent, and 500 μL acetonitrile containing 0.2% acetic acid as the organic solvent provided the optimum conditions for processing a 100 μL whole blood sample. The recoveries of the analytes spiked into whole blood at 0.5 μg/mL ranged between 59% and 93%. Although the addition of the graphitized carbon Envi-carb for cleanup decreased the recoveries of zolpidem and its carboxylate-form metabolite M-1, it was very effective in avoiding interferences by cholesterol. The present method can provide a rapid, effective, user-friendly, and relatively hygienic method for the simultaneous extraction of a wide range of drugs and metabolites in whole blood specimens.