Toxicity and behavioural effects of ocfentanil and 2-furanylfentanyl in zebrafish larvae and mice.

The introduction of the so-called New Psychoactive Substances represents a problem of global concern due to several factors, including multiplicity of structures, poorly known activity, short half-life in the market, lack of pure standards etc. Among these problems, of the highest relevance is also the lack of information about metabolism and adverse effects, which must be faced using simple and low-cost animal models. On these grounds, the present work has been carried out on 5 days post fertilization zebrafish (Danio rerio) larvae in comparison with adult mice (Mus musculus). Ocfentanil and 2-furanylfentanyl were administered at different concentrations to zebrafish larvae (1, 10 µM) and mice (0.1, 1, 6, 15 mg/kg). The behavioural assay showed a decrease in basal locomotor activity in zebrafish, whereas in mice this effect was evident only after the mechanical stimulus. Larva extracts and mice urine were analysed by using liquid chromatography coupled to high resolution mass spectrometry to identify the metabolic pathways of the fentanyl analogs. For 2-furanylfentanyl, the most common biotransformations observed were hydroxylation, hydration and oxidation in zebrafish larvae, whereas mice produced mainly the dihydrodiol metabolite. Hydroxylation was the major route of metabolism for ocfentanil in zebrafish larvae, while in mice the O-demethylated derivative was the main metabolite. In addition, a study was conducted to evaluate morphological effects of the two drugs on zebrafish larvae. Malformations were noticeable only at the highest concentration of 2-furanylfentanyl, whereas no significant damage was observed with ocfentanil. In conclusion, the two animal models show similarities in behavioral response and in metabolism, considering the different biological investigated.

Sensorimotor Alterations Induced by Novel Fentanyl Analogs in Mice: Possible Impact on Human Driving Performances.

Operating a vehicle is a complex task that requires multiple cognitive functions and psychomotor skills to cooperate. Driving might be impaired by licit or illicit drugs, including novel psychoactive substances (NPS) and novel synthetic opioids (NSO), the effects of which are still yet to be elucidated in humans. In the present work, a revision of the literature regarding the psychomotor impairing effects of Fentanyl (FENT) and three analogues (Acrylfentanyl, Ocfentanyl and Furanylfentanyl) is presented, as emerged by experimental studies on humans, driving under the influence of a drug (DUID) and intoxication cases. An experimental study on a mouse model evaluated the sensorimotor alterations induced by FENT and the three fentalogs. Acute systemic administration of the four opioids (0.01-15 mg/kg i.p.) dose-dependently decreased the visual object and placing tests, the acoustic and the tactile responses of mice. The preclinical data are in accordance with the data that emerged from the revision of the literature regarding experimental data on humans, driving under the influence of drugs and intoxication cases, suggesting that novel synthetic opioids might affect the psychomotor performances on daily human tasks with a particular focus on driving.

The Genotoxicity of Acrylfentanyl, Ocfentanyl and Furanylfentanyl Raises the Concern of Long-Term Consequences.

Three fentanyl analogues Acrylfentanyl, Ocfentanyl and Furanylfentanyl are potent, rapid-acting synthetic analgesics that recently appeared on the illicit market of new psychoactive substances (NPS) under the class of new synthetic opioids (NSO). Pharmacotoxicological data on these three non-pharmaceutical fentanyl analogues are limited and studies on their genotoxicity are not yet available. Therefore, the aim of the present study was to investigate this property. The ability to induce structural and numerical chromosomal aberrations in human lymphoblastoid TK6 cells was evaluated by employing the flow cytometric protocol of the in vitro mammalian cell micronucleus test. Our study demonstrated the non-genotoxicity of Fentanyl, i.e., the pharmaceutical progenitor of the class, while its illicit non-pharmaceutical analogues were found to be genotoxic. In particular, Acrylfentanyl led to a statistically significant increase in the MNi frequency at the highest concentration tested (75 µM), while Ocfentanyl and Furanylfentnyl each did so at both concentrations tested (150, 200 µM and 25, 50 µM, respectively). The study ended by investigating reactive oxygen species (ROS) induction as a possible mechanism linked to the proved genotoxic effect. The results showed a non-statistically significant increase in ROS levels in the cultures treated with all molecules under study. Overall, the proved genotoxicity raises concern about the possibility of serious long-term consequences.

Use of fentanyl, butyrfentanyl and furanylfentanyl as discussed on Polish online forums devoted to 'designer drugs'. / Uzywanie fentanylu, butyrylofentanylu i furanylofentanylu w opinii uzytkowników polskich forów internetowych poswieconych "dopalaczom".

OBJECTIVES: The study was aimed to analyze information posted by users of synthetic opioids on Polish online drug discussion forums. Special emphasis was given to sources of drugs and their availability, routes of administration, dosages, expected and toxic effects. METHODS: 6,143 reports related to synthetic opioids, posted between 2005 and mid 2019 on three widely available popular Polish online forums devoted to psychoactive substances, i.e., hyperreal.info/talk, dopek.info and forum.dopalamy, were collected and analyzed. The article presents data on three most popular opioids, i.e., fentanyl, butyrfentanyl and furanylfentanyl. RESULTS: Fentanyl was the most widely used and relatively easily accessible synthetic opioid in Poland. Butyrfentanyl and furanylfentanyl were far less popular. The main source of fentanyl was diversion of medicines, notably transdermal patches. Fentanyl, butyrfentanyl and furanylfentanyl are administered orally, buccally, sublingually, intranasally, by inhalation and intravenously. Concomitant use of fentanyl and its derivatives with other psychoactive compounds increases the risk of severe adverse effects. CONCLUSIONS: Our study contributed to amore comprehensive understanding of problems related to abuse of fentanyl, butyrfentanyl and furanylfentanyl in Poland. In the light of the relatively high popularity of pharmaceutical fentanyl used for non-medical purposes, there is an urgent need for more strict control over illegal sales of fentanyl transdermal preparations via the Internet, as well as disposal of used patches. Furthermore, patients using fentanyl should be warned that giving it to another person is against the law, and may lead to development of addiction and other serious health consequences. It is important to educate the society in order to increase awareness of the problem of opioid use, especially by young people, and to pay attention to signals which may indicate addiction among family members.

In vitro and in vivo pharmaco-dynamic study of the novel fentanyl derivatives: Acrylfentanyl, Ocfentanyl and Furanylfentanyl.

Fentanyl derivatives (FENS) belongs to the class of Novel Synthetic Opioids that emerged in the illegal drug market of New Psychoactive Substances (NPS). These substances have been implicated in many cases of intoxication and death with overdose worldwide. Therefore, the aim of this study is to investigate the pharmaco-dynamic profiles of three fentanyl (FENT) analogues: Acrylfentanyl (ACRYLF), Ocfentanyl (OCF) and Furanylfentanyl (FUF). In vitro, we measured FENS opioid receptor efficacy, potency, and selectivity in calcium mobilization studies performed in cells coexpressing opioid receptors and chimeric G proteins and their capability to promote the interaction of the mu receptor with G protein and ß-arrestin 2 in bioluminescence resonance energy transfer (BRET) studies. In vivo, we investigated the acute effects of the systemic administration of ACRYLF, OCF and FUF (0.01-15 mg/kg i.p.) on mechanical and thermal analgesia, motor impairment, grip strength and cardiorespiratory changes in CD-1 male mice. Opioid receptor specificity was investigated in vivo using naloxone (NLX; 6 mg/kg i.p) pre-treatment. In vitro, the three FENS were able to activate the mu opioid receptor in a concentration dependent manner with following rank order potency: FUF > FENT=OCF > ACRYLF. All compounds were able to elicit maximal effects similar to that of dermorphin, with the exception of FUF which displayed lower maximal effects thus behaving as a partial agonist. In the BRET G-protein assay, all compounds behaved as partial agonists for the ß-arrestin 2 pathway in comparison with dermorphin, whereas FUF did not promote ß-arrestin 2 recruitment, behaving as an antagonist. In vivo, all the compounds increased mechanical and thermal analgesia with following rank order potency ACRYLF = FENT > FUF > OCF and impaired motor and cardiorespiratory parameters. Among the substances tested, FUF showed lower potency for cardiorespiratory and motor effects. These findings reveal the risks associated with the use of FENS and the importance of studying the pharmaco-dynamic properties of these drugs to better understand possible therapeutic interventions in the case of toxicity.

Challenges Related to Three Cases of Fatal Intoxication to Multiple Novel Synthetic Opioids.

In the last two decades, a large increase in opioid overdose death rates has been recorded in North America. This phenomenon, related to the misuse of prescription opioids, has been dubbed an "opioids crisis". Recent years have seen the entrance of novel synthetic opioids (NSO) on the market, compounding the fatal intoxications issue. This brings several challenges for forensic toxicology laboratories: an increased number of cases, a large number of novel structurally similar compounds to include in screening analytical methods, the low concentration of drugs in biological fluids, and the challenging interpretation in the absence of sufficient literature. Three cases of fatal intoxication highlighting those challenges are presented, complete with post-mortem concentrations in cardiac blood, femoral blood and urine. Toxicological screening and quantitative analyses were performed on the biological specimens. In the first and second cases, furanylfentanyl, U-47700 and 4-anilino-N-phenethylpiperidine (4-ANPP) were detected at similar concentrations in cardiac blood. In the third case, a total of seventeen different NSO were detected. All intoxications showed a combination of NSO and other drugs. These three cases appear to be the harbinger of an increased NSO prevalence in the province of Québec, Canada.

Single-calibrant quantification of seized synthetic opioids by liquid chromatography-chemiluminescence nitrogen detection.

Drug seizures involving a wide variety of emerging new psychoactive substances (NPS) call for new approaches for instant quantification and valuation. Liquid chromatography-chemiluminescence nitrogen detection (LC-CLND) was used in the quantification of opioids with a single secondary standard (caffeine), utilizing the detector's equimolar response to nitrogen. The mean N-equimolarity of CLND for ten fentanyl derivatives and U-47700 by the present LC-CLND method was 96.4% (range 91-101%). The furanylfentanyl samples consisted of 112 powdery samples with a mean (median, range) hydrochloride purity of 13% (4.9%, 0.08-100%). The purity distribution of the furanylfentanyl samples was distinctly bipartite, showing only lower than 9% (N=98) and higher than 60% (N=14) purities. The carfentanil samples consisted of eight brownish sticky samples with a mean (median, range) hydrochloride purity of 0.064% (0.063%, 0.052-0.092%). The U-47700 samples consisted of seven powdery samples with a mean (median, range) hydrochloride purity of 89.0% (100%, 51-100%). The present application to synthetic opioid analysis widens the scope of the established LC-CLND method, previously found useful for single-calibrant quantification of stimulant/hallucinogenic and cannabinoid type of NPS.

Highly potent fentanyl analogs: apnea from exposure to small quantities of ß-hydroxyfentanyl and furanylfentanyl.

Context: Fentanyl analogs are synthetic opioids that bind to mu receptors with high potency. We report two cases where users developed apnea and required naloxone reversal after exposure to small quantities of the fentanyl analogs, furanylfentanyl and ß-hydroxyfentanyl. Case details: A 19 year-old woman reported insufflating a small number of granules of "fentanyl" powder and developed apnea. A 22 year-old woman touched her tongue to powdered "fentanyl" to treat a migraine headache and became apneic. Results: Furanylfentanyl was identified in the first patient's serum (3.6 ng/mL furanylfentanyl), urine (17.6 ng/mL furanylfentanyl) , and in the product (109mg/g powder). ß-hydroxyfentanyl was detected in the second patient's serum (6.5 ng/mL ß-hydroxyfentanyl) and in the product (120 mg/g powder). Discussion: In both cases, furanylfentanyl and ß-hydroxyfentanyl were identified in the serum/plasma and urine. Fentanyl analogs were detected in the product at 109-120mg per gram of powder, which suggests that a 500mcg dose of fentanyl analog is the equivalent to 4.17-4.59mg of powder, or about the mass in 1/500th of a packet of sugar. Unique aspects of these cases are the rarely reported use of furanylfentanyl and ß-hydroxyfentanyl, intentional insufflation of "fentanyl" for therapeutic and recreational use, the small quantities of powder ingested, and the use of non-targeted analysis to identify the fentanyl analogs.

A GC-MS method for the determination of furanylfentanyl and ocfentanil in whole blood with full validation.

PURPOSE: Fentanyl analogues are popular in recent years among drug addicts and have been related to many overdoses and deaths worldwide. Furanylfentanyl, ocfentanil, acetylfentanyl and butyrfentanyl are among the most common of these drugs. Methods for the determination of furanylfentanyl and ocfentanil by gas chromatography-mass spectrometry (GC-MS) in biological samples do not exist, and therefore, their development would be extremely useful for routine toxicological analysis. METHODS: A GC-MS method was developed and fully validated for the determination of furanylfentanyl and ocfentanil in whole blood. This method was also suitable for the determination of acetylfentanyl and butyrfentanyl. The method included solid-phase extraction after protein precipitation using acetonitrile, and it was applied during the toxicological investigation of forensic cases. Methadone-d 3 was used as internal standard for the quantification of the analytes. RESULTS: The limit of detection and limit of quantification values were 0.30 and 1.0 ng/mL for furanylfentanyl and ocfentanil and 0.15 and 0.50 ng/mL for acetylfentanyl and butyrfentanyl, respectively. The calibration curves were linear (R 2 ≥ 0.993) from 1.00 to 100 ng/mL for furanylfentanyl and ocfentanil and from 0.50 to 50.0 ng/mL for acetylfentanyl and butyrfentanyl. The recoveries were not lower than 85%, while accuracies and precisions were not greater than 6.0% (% error) and 8.0% (% relative standard deviation), respectively, for all four fentanyl analogues. CONCLUSIONS: The developed method is the first one in the literature for the detection of furanylfentanyl and ocfentanil in biological fluids by GC-MS, and it provides very high sensitivity comparable to that by liquid chromatography-tandem mass spectrometry.

In vitro Characterization of NPS Metabolites Produced by Human Liver Microsomes and the HepaRG Cell Line Using Liquid Chromatographyhigh Resolution Mass Spectrometry (LC-HRMS) Analysis: Application to Furanyl Fentanyl.

BACKGROUND: Identification of metabolites is of importance in the challenge of new psychoactive substances (NPS) as it could improve the detection window in biological matrices in clinical and forensic cases of intoxication. Considering the numerous and diverse NPS reported each year, producers increasingly appear today to be targeting non-controlled synthetic opioids, involving fentanyl derivatives such as furanyl fentanyl (Fu-F). OBJECTIVE: This work aims to investigate and compare metabolites of Fu-F using two in vitro experimental approaches. METHODS: CYP- and UGT-dependent metabolites of Fu-F were investigated by means of analyses of both human liver microsome (HLM) and hepatic (HepaRG) cell line incubates using liquid chromatography with high-resolution mass detection and, subsequently, compared and confronted to recently published data. RESULTS: Seventeen Fu-F metabolites were produced and several metabolic pathways can be postulated. HLMs and HepaRG cultures appear to be complementary: HepaRG cells produced 9 additional metabolites, but which appear to be minor in vivo metabolites. Specific* and/or abundant Fu-F metabolites are dihydrodiol-Fu-F*, norFu-F* and despropionylfentanyl. However, norFu-F seems to be inconstantly observed in in vivo cases. Furthermore, a sulfate metabolite presents at significant rate in urine obtained from FU-F users was not identified here, as in another in vitro study. CONCLUSION: HLMs represent an acceptable first choice tool for a single NPS metabolism study in forensic laboratories. Dihydrodiol-Fu-F and despropionylfentanyl could be proposed as reliable metabolites to be recorded in HRMS libraries in order to improve detection of Fu-F users. Nevertheless, additional verifications of in vivo data remain necessary to confirm relevant blood and urinary metabolites of Fu-F.

Intoxications involving acrylfentanyl and other novel designer fentanyls - results from the Swedish STRIDA project.

BACKGROUND: The number of new psychoactive substances (NPS) introduced through the online recreational drugs market increases continuously. This report from the Swedish STRIDA project describes analytically confirmed intoxications involving the novel fentanyl analogs acrylfentanyl, 4-chloroisobutyrfentanyl (4Cl-iBF), 4-fluoroisobutyrfentanyl (4F-iBF), and tetrahydrofuranfentanyl (THF-F), and cyclopentylfentanyl in a drug product. METHODS: Patients with suspected NPS exposure presenting in emergency departments (ED) or intensive care units (ICU) in Sweden and requiring hospital care are invited to the STRIDA project. NPS analysis of serum and urine samples was performed by multi-component liquid chromatography-mass spectrometry. Data on clinical features were retrieved from telephone consultations with the Swedish Poisons Information Centre and from medical records. RESULTS: Between April and October 2016, eleven intoxications involving acrylfentanyl (8 cases), acrylfentanyl together with 4Cl-iBF (1), 4F-iBF (1), and THF-F (1) were analytically confirmed. Patients were aged 19-51 (median 28) years and 91% were men. Six (55%) were monitored at the ED, and five admitted to the ICU. Typical clinical features were decreased consciousness, respiratory depression, and miosis. In 8 cases, the antidote naloxone was administered to counter the opioid effects. The 4F-iBF positive patient eventually died of brain edema. The serum acrylfentanyl concentration (n = 8) ranged 0.5-2.1 (median 0.9) ng/mL, and in urine (n = 9) 0.2-10.5 (mean 4.6, median 5.2) µg/mmol creatinine. For 4Cl-iBF, 4F-iBF, and THF-F (n = 1 each), higher serum (5-45 ng/mL) and urine (11-136 µg/mmol creatinine) concentrations were found. Other NPS (e.g., flunitrazolam) and/or classical drugs were detected in five cases. In early 2016, nasal sprays with a claimed content of acrylfentanyl brought to hospital by patients or obtained by test purchase were demonstrated to instead contain fentanyl. CONCLUSIONS: Potentially life-threatening opioid toxicity was seen in 11 acute intoxications involving the fentanyl analogs acrylfentanyl, 4Cl-iBF, 4F-iBF, and THF-F, which are available through open Internet trading. All patients were supported with acute and intensive hospital care, and naloxone was effective to reverse the opioid symptoms. One patient died of brain edema.

Intoxications involving the fentanyl analogs acetylfentanyl, 4-methoxybutyrfentanyl and furanylfentanyl: results from the Swedish STRIDA project.

BACKGROUND: Potent and potentially harmful new psychoactive substances (NPS) are continuously introduced on the recreational drugs market. This report from the Swedish STRIDA project describes analytically confirmed cases of intoxication involving the fentanyl analogs acetylfentanyl, 4-methoxybutyrfentanyl, and furanylfentanyl. METHODS: Patients with suspected NPS exposure presenting in emergency departments and intensive care units in Sweden and requiring hospital care are invited to the STRIDA project. Toxicological analysis of serum and urine samples was performed by multi-component liquid chromatographic-mass spectrometric methods. Data on clinical features were retrieved from telephone consultations with the Swedish Poisons Information Centre and from medical records. RESULTS: Between April and November 2015, 14 analytically confirmed intoxications involving acetylfentanyl (nine cases), 4-methoxybutyrfentanyl (3), furanylfentanyl (1), and 4-methoxybutyrfentanyl together with furanylfentanyl (1) were identified. The patients were aged 20-40 (mean 28.5) years and 86% were men. Twelve patients (86%) were admitted to intensive care, where two required intubation and mechanical ventilation. Typical clinical features were decreased consciousness, respiratory depression, and miosis. In eight cases, the antidote naloxone was administered to counter the effects. The serum acetylfentanyl concentration (N = 7) was 0.6-51.6 (mean 18.3 and median 14.8) ng/mL, and in urine (N = 8) 0.1-686 (mean 155 and median 66.6) ng/mmol creatinine. The serum 4-methoxybutyrfentanyl concentration (N = 2) was 1.3 and 3.1 ng/mL, and 5.1-51.3 ng/mmol creatinine in urine (N = 3). For furanylfentanyl, the serum concentrations were 4.4 and 148 ng/mL and in urine 9.2 and 85 ng/mmol creatinine, respectively. In 13 cases (93%), other NPS and/or classical drugs were also detected. Drug products brought to hospital by patients contained acetylfentanyl (nasal spray and pink tablet), 4-methoxybutyrfentanyl (green tablet), furanylfentanyl/traces of 4-methoxybutyrfentanyl (nasal spray), and 4-fluorobutyrfentanyl (purple tablet). CONCLUSION: Potentially life-threatening opioid toxicity was seen in acute intoxications involving acetylfentanyl, 4-methoxybutyrfentanyl, and furanylfentanyl. Intensive care treatment for one month was necessary in one acetylfentanyl case and one acetylfentanyl patient died from cerebral hemorrhage.