Norephedrines as metabolites of ( 14 C)amphetamine in urine in man

Detection of emerging patterns of drug misuse in sports via wastewater monitoring: A mini-review and potential strategies

Biological testing is a key component of the current anti-doping programme implemented by the authorities to detect doping in sports. Strategies such as longitudinal individualised data analysis and sport-specific analysis have been developed to increase the comprehensiveness of the testing. However, the trends of drug misuse in sports might not be effectively captured through today's testing plan. Wastewater testing, assembling individual-level data of a designated group to produce population-level results in one single aggregated sample, can be employed to as a complementary strategy offering added value for doping control. This paper presents an updated summary of the status of anti-doping testing and analytical methodologies for wastewater. The available literature on wastewater-based analyses of drugs prohibited in sports is reviewed. Publications surrounding sporting activities or competitions and others relevant to sports doping are selected. We debate between potential strategies and major limitations of using wastewater monitoring in anti-doping. Knowledge gaps and research directions, specifically on metabolites, stability, sensitivity, and ethical and legal considerations, are discussed. Choosing different wastewater sampling sites allows target sub-population that involved competing athletes and potentially reveal sport-specific or athlete-level-specific behaviour. Sampling from on-board toilets or athlete villages could target international-level athletes, sampling from the dormitories of national training centres allows monitoring of national-level athletes on a daily basis, and sampling from sports stadiums provides a full picture of drug use in the general population during an event. Confounding occurs as (i) the presence of non-athlete composition and the difficulty of analyses to be completely selective to the athlete population; and (ii) the identification of compounds prescribed legitimately with Therapeutic Use Exemptions, only banned in-competition, and naturally occurring. The practicalities of the approach are contextualised in monitoring the non-threshold substances such as anabolic agents, selective androgen receptor modulators, metabolic modulators, and hypoxia-inducible factor activators.

Enantioselective Quantification of Amphetamine and Metabolites in Serum Samples: Forensic Evaluation and Estimation of Consumption Time

In forensic toxicology, amphetamine intoxications represent one of the most common case groups and present difficult questions for toxicologists. Estimating the time of consumption and the current influence of the stimulant is particularly difficult when only total amphetamine concentrations are considered. Stereoselective analysis and the consideration of metabolites can provide valuable information to facilitate interpretation. An enantioselective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for detection of amphetamine, norephedrine and 4-hydroxyamphetamine was developed. Validation showed satisfactory selectivity, sensitivity, linearity (0.5-250 ng/mL), precision and accuracy for all enantiomers. The method was applied to a collective of 425 forensic serum samples and 30 serum samples from psychiatric inpatients stating their last time of amphetamine consumption. Norephedrine and 4-hydroxyamphetamine were detected more frequently at higher amphetamine concentrations and at lower amphetamine (R)/(S) concentration ratios, possibly indicating recent consumption. Mean (R)/(S) ratio of amphetamine was 1.14, whereas higher ratios (mean 1.36) were found for amphetamine concentrations below 100 ng/mL. The (R)/(S) ratios of psychiatric inpatients significantly correlated with the reported time intervals to last consumption. The use of amphetamine (R)/(S) ratios and the simultaneous detection of metabolites are promising factors that can facilitate estimation of consumption time and current impairment.

Wastewater-based tracing of doping use by the general population and amateur athletes

The present study investigates the applicability of the chemical analysis of wastewater to assess the use of doping substances by the general population and amateur athletes. To this end, an analytical methodology that can identify and quantify a list of 15 substances from the groups of anabolic steroids, weight loss products, and masking agents in wastewater has been developed. The method uses solid phase extraction to increase the detection sensitivity of the target analytes, expected to be present at very low concentrations (ng L⁻¹ range), and decrease possible matrix interferences. Instrumental analysis is performed by liquid chromatography coupled to high-resolution mass spectrometry, allowing data acquisition in both full scan and tandem MS mode. The method has been successfully validated at two concentration levels (50 and 200 ng L⁻¹) with limits of quantification ranging between 0.7 and 60 ng L⁻¹, intra- and inter-day precision expressed as relative standard deviation below 15%, procedural recoveries between 60 and 160% and matrix effects ranging from 45 to 121%. The stability of the analytes in wastewater was evaluated at different storage temperatures illustrating the importance of freezing the samples immediately after collection. The application of the method to 24-h composite wastewater samples collected at the entrance of three wastewater treatment plants and one pumping station while different sport events were taking place revealed the presence in wastewater, and hence the use, of the weight loss substances ephedrine, norephedrine, methylhexanamine, and 2,4-dinitrophenol. The use of these stimulants was visible just prior and during the event days and in greater amounts than anabolic steroids or masking agents.

Graphical abstract

Intermolecular interactions between DNA and methamphetamine, amphetamine, ecstasy and their major metabolites

In this work, we carried out a theoretical investigation regarding amphetamine-type stimulants, which can cause central nervous system degeneration, interacting with human DNA. These include amphetamine, methamphetamine, 3,4-Methylenedioxymethamphetamine (also known as ecstasy), as well as their main metabolites. The studies were performed through molecular docking and molecular dynamics simulations, where molecular interactions of the receptor-ligand systems, along with their physical-chemical energies, were reported. Our results show that 3,4-Methylenedioxymethamphetamine and 3,4-Dihydroxymethamphetamine (ecstasy) present considerable reactivity with the receptor (DNA), suggesting that these molecules may cause damage due to human-DNA. These results were indicated by free Gibbs change of bind (ΔG_bind) values referring to intermolecular interactions between the drugs and the minor grooves of DNA, which were predominant for all simulations. In addition, it was observed that 3,4-Dihydroxymethamphetamine (ΔG_bind = -13.15 kcal/mol) presented greater spontaneity in establishing interactions with DNA in comparison to 3,4-Methylenedioxymethamphetamine (ΔG_bind = -8.61 kcal/mol). Thus, according with the calculations performed our results suggest that the 3,4-Methylenedioxymethamphetamine and 3,4-Dihydroxymethamphetamine have greater probability to provide damage to human DNA fragments.

Evaluation of postmortem drug concentrations in cerebrospinal fluid compared with blood and pericardial fluid

In forensic toxicology, body fluids are important materials not only as alternatives to blood but also for investigation of postmortem drug redistributions and pharmaco-/toxicokinetic analysis; however, there are limited data on postmortem drug distributions in cerebrospinal fluid (CSF). The present study reviewed toxicological data of autopsy cases (n=103), in which drugs were detected in CSF using gas chromatography/mass spectrometry (GC/MS), to investigate drug concentrations in CSF, compared with blood and pericardial fluid (PCF) concentrations. Oral/injected amphetamines (n=23) showed similar CSF and blood/PCF concentrations with partly lower CSF concentrations (about ×0.5-1.1). CSF concentrations of the venous anesthetic midazolam (n=7) were lower with poor correlations. Oral caffeine (n=15), acetaminophen (n=7), chlorpheniramine (n=6), dihydrocodeine (n=6), and phenobarbital (n=21) showed equivalent to lower CSF concentrations (about ×0.2-1.2), compared with blood and PCF concentrations; however, CSF phenobarbital concentrations were high in a fatal intoxication case. CSF concentrations of phenothiazine derivatives (n=29) were markedly lower (about ×0.1) than blood/PCF concentrations. The distribution of the local anesthetic lidocaine used in critical medical care (n=49) markedly varied by case. These findings suggest that CSF is useful in routine forensic toxicology as an alternative to blood as well as for investigating pharmaco-/toxicokinetics and postmortem redistributions.

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.

Stereoselectivity of the aliphatic hydroxylation of 6-n-propylchromone-2-carboxylic acid in rat and guinea pig

Following administration of 6-n-propylchromone-2-carboxylic acid (6-n-PCCA) (500 mumol/kg) to male rats, three metabolic products were detected and isolated from the 0-24 h urine. All were identified as resulting from oxidation exclusively along the 6-n-propyl moiety. Some 66% of the dose was excreted in the 0-24 h urine, 55% of which was 6-PCCA, with 15% as (6-1'-hydroxypropyl)chromone-2-carboxylic acid (6-1'-HPCCA), 22% as 6-(2'-hydroxypropyl)chromone-2-carboxylic acid (6-2'-HPCCA), and 4% as 6-3'-carboxypropyl)chromone-2-carboxylic acid (6-3'-CPCCA). Derivatization of the methyl esters of the hydroxylated metabolites with S-alpha-methoxy-alpha-(trifuloromethyl)-phenylacetyl chloride (Mosher's reagent) allowed the evaluation of urinary enantiomeric composition by HPLC and assignment of their absolute configurations by NMR. This was found to be 90:10 (R/S) for 6-2'-HPCCA, and 7:93 (R/S) for 6-1'-HPCCA. When rats were dosed with the racemic 1'- and 2-hydroxy metabolites; no stereoselective metabolism or excretion was observed. Administration of 6-n-PCCA to male guinea pigs revealed that this species was unable to metabolise this compound.

Rats become acutely tolerant to cathine after amphetamine or cathinone administration

The drug discrimination paradigm was used to evaluate in rats the ability of the discriminate response to either 0.8 mg/kg d-amphetamine or 0.8 mg/kg l-cathinone to generalize to 2.4-6.0 mg/kg of the active cathinone metabolite d-norpseudoephedrine, also known as cathine. When tested 24 h after vehicle administration, cathine generalized in a dose-related fashion in rats (n = 6) trained with cathinone (ED50 = 3.03 mg/kg) and in rats (n = 8) trained with amphetamine (ED50 = 2.93 mg/kg). In contrast, when cathine was tested 24 h after the administration of either amphetamine or cathinone, it produced significantly decreased discriminative performance. The possibility that this acute tolerance may have been produced by release, and subsequent depletion, of brain dopamine was tested by pretreating rats with the dopamine release inhibitor CGS 10746B. When CGS 10746B was administered prior to cathinone it significantly decreased cathinone discrimination. In addition, acute tolerance to cathine at 24 h after vehicle-cathinone co-administration was reversed when cathine was tested 24 h after CGS 10746B-cathinone co-administration. The results suggest that cathinone-produced discriminative stimulus, as well as the acute tolerance to cathine, may be dopaminergically mediated.

P-hydroxy-norephedrine as a possible mediator causing the reduction of oral intake of D-amphetamine in rats

In rats D-amphetamine is predominantly metabolized by hydroxylation to p-hydroxy-norephedrine (p-HNE); in guinea pigs, however, by deamination to benzoic acid. After 2-3 days on dosages of 1 mg/kg per day and more rats begin to reduce their oral intake of the stimulant whereas guinea pigs do not. In the present study we examined the hypothesis that the formation of p-HNE in the CNS is partially responsible for this aversion. To determine the elimination of D-amphetamine and the increase in p-HNE, groups of male Wistar rats were given various doses (0.5-5 mg/kg per day) of D-amphetamine in their drinking water intragastrically and intravenously. D-Amphetamine in the brain was determined by radioimmunoassay, p-HNE by high performance liquid chromatography followed by electrochemical detection. In contrast to the concentration of D-amphetamine, the p-HNE-content is independent of the route of administration; after oral treatment it showed a linear increase. The results reveal that p-HNE induces the aversion to the stimulant and that the ratio of D-amphetamine to its metabolite determines the onset of this aversion. No p-HNE was found in the brain of guinea pigs. Guinea pigs do not show any aversion to drinking D-amphetamine solutions, even in high dosages.

Identification of phenolic acids in human urine by ion monitoring

1. Two-different double derivatization techniques and two different g.l.c. systems were used to separate isomeric phenolic carboxylic acids in normal human urine. 2. Carboxylic acids were converted into n-butyl esters and phenolic functions into trifluoroacetic acid esters. 3. n-Butyl trifluoroacetoxybenzoates were separated by g.l.c. and detected by mass spectrometric single-ion monitoring. 4. Trifluoroacetates were hydrolysed under mild conditions, and liberated phenolic groups were subjected to flash methylation. 5. n-Butyl methoxybenzoates were separated by g.l.c. and detected by flame ionization. 6. All derivatives were identified by comparison of retention times and mass spectra with those of authentic reference standards. 7. The urine of a normal vegetarian volunteer was examined. 8. The presence of meta- and para-hydroxybenzoic acids, vanillic acid and isovanillic acid was confirmed by unambiguous techniques.

The synthesis of tritium-labelled human corticotropin of high specific radioactivity

Human [[3,5-3H2]Tyr23]corticotropin-(1-39)-nonatriacontapeptide of specific radioactivity 25.2 Ci/mmol, identical with unlabelled human corticotropin by several criteria, was prepared via the fully protected di-iodotyrosine compound. The latter was synthesized by classical procedures.

Comparative effects of d-amphetamine, l-amphetamine, and methylphenidate on mood in man

The comparative effects of d-amphetamine, l-amphetamine, and methylphenidate were assessed in 16 normal subjects, using a double-blind, crossover placebo-controlled design. Within the dose range tested, the efficacy ratio of d-amphetamine:l-amphetamine was about 2:1, and graphic presentation of dose response scores indicated a relatively small difference in potency between the amphetamine isomers. Methylphenidate was intermediate in efficacy between d-amphetamine and l-amphetamine. The efficacy ratios for d-amphetamine:l-amphetamine on increasing euphoric mood in man were similar to the previously reported ratios of there two isomers in inducing or exacerbating psychosis in humans. These findings do not support the suggestion, made by Snyder and others, that the differential effects of d-amphetamine vs. l-amphetamine on a specific type of behavior in man could be utilized to infer the predominance of noradrenergic vs. dopaminergic mediation of amphetamine's effects on this behavior.

The in vitro metabolism of 2-nitroso-1-phenylpropane dimer by fortified 9000g supernatants from rabbit liver

2-Nitroso-1-phenylpropane dimer, a postulated metabolic product of amphetamine, was metabolized by fortified 9000 g supernatants from rabbit liver, mainly by oxidation on the carbon beta to the nitrogen to form a "beta-hydroxylated nitroso dimer'. The corresponding nitro compound, ketone and alcohol were also products, the latter two but not the former being cofactor dependent. The nitroso compound was not metabolically reduced under the conditions used.

The metabolism of (-)-ephedrine in man

The metabolic fate of orally administered (-)-[14C]-ephedrine has been studied in 3 human subjects and the urinary excretion of metabolites determined quantitatively by solvent extraction, paper chromatography and reverse isotope dilution procedures. Following an oral dose of the drug (0.35 mg/kg, 1.6 muCi), 97% of the dose was excreted in the urine within 48 h, 88% in the first 24 h. Unchanged drug was the major urinary excretory product (53-74%), with N-demethylation occurring to a variable extent (8-20%) although there was little interindividual variation in urine pH. Oxidative deamination was also variable (4-13%); the main identified products of this were benzoic acid (free and conjugated) and 1,2-dihydroxy-1-phenylpropane (free and conjugated). No phenolic metabolites could be detected, and thus it would appear that these compounds cannot be implicated in the acquisition of tolerance to ephedrine which can occur on repeated dosage.

Metabolic N- and alpha-C-oxidation of norephedrine by rabbit liver microsomal fractions and synthesis of the metabolic pdocuts

The products of metabolism of norephedrine by 10 000 g fractions of rabbit liver microsomes have been shown to be norephedrine hydroxylamine, l-hydroxy-2-oxo-l-phenylpropane oxime, 1-hydroxy-2-oxo-1-phenylpropane, 1,2-dihydroxy-l-phenylpropane (erythro). N-Oxidation was at least as important as α-C-oxidation. The synthesis and properties of the metabolic products are described.

Species differences in the metabolism of norephedrine in man, rabbit and rat

1. (+/-)-2-Amino-1-phenyl[1-(14)C]propan-1-ol ([(14)C]norephedrine) was administered orally to man, rat and rabbit and the metabolites excreted in the urine were identified and measured. Pronounced species differences in the metabolism of the drug were found. 2. Three male human subjects, receiving 25mg each of [(14)C]norephedrine hydrochloride, excreted over 90% of the (14)C in the first day. The main metabolite was the unchanged drug (86% of the dose) and minor metabolites were hippuric acid and 4-hydroxynorephedrine. 3. In rats given 12mg of the drug/kg almost 80% of the (14)C administered was excreted in the first day. The major metabolites in the urine were the unchanged drug (48% of the dose), 4-hydroxynorephedrine (28%) and trace amounts of side-chain degradation products. 4. Rabbits given 12mg of the drug/kg excreted 85-95% of the dose of (14)C in the urine in the first 24h after dosing. The major metabolites in the urine were conjugates of 1,2-dihydroxy-1-phenylpropane (31% of the dose) and of 1-hydroxy-1-phenylpropan-2-one (27%) and hippuric acid (20%). The unchanged drug was excreted in relatively small amounts (8%).

Metabolism of ( 14 C)methamphetamine in man, the guinea pig and the rat

1. The metabolites of (+/-)-2-methylamino-1-phenyl[1-(14)C]propane ([(14)C]methamphetamine) in urine were examined in man, rat and guinea pig. 2. In two male human subjects receiving the drug orally (20mg per person) about 90% of the (14)C was excreted in the urine in 4 days. The urine of the first day was examined for metabolites, and the main metabolites were the unchanged drug (22% of the dose) and 4-hydroxymethamphetamine (15%). Minor metabolites were hippuric acid, norephedrine, 4-hydroxyamphetamine, 4-hydroxynorephedrine and an acid-labile precursor of benzyl methyl ketone. 3. In the rat some 82% of the dose of (14)C (45mg/kg) was excreted in the urine and 2-3% in the faeces in 3-4 days. In 2 days the main metabolites in the urine were 4-hydroxymethamphetamine (31% of dose), 4-hydroxynorephedrine (16%) and unchanged drug (11%). Minor metabolites were amphetamine, 4-hydroxyamphetamine and benzoic acid. 4. The guinea pig was injected intraperitoneally with the drug at two doses, 10 and 45mg/kg. In both cases nearly 90% of the (14)C was excreted, mainly in the urine after the lower dose, but in the urine (69%) and faeces (18%) after the higher dose. The main metabolites in the guinea pig were benzoic acid and its conjugates. Minor metabolites were unchanged drug, amphetamine, norephedrine, an acid-labile precursor of benzyl methyl ketone and an unknown weakly acidic metabolite. The output of norephedrine was dose-dependent, being about 19% on the higher dose and about 1% on the lower dose. 5. Marked species differences in the metabolism of methamphetamine were observed. The main reaction in the rat was aromatic hydroxylation, in the guinea pig demethylation and deamination, whereas in man much of the drug, possibly one-half, was excreted unchanged.