Characterization and <i>in vitro</i> phase I microsomal metabolism of designer benzodiazepines — an update comprising adinazolam, cloniprazepam, fonazepam, 3‐hydroxyphenazepam, metizolam and nitrazolam

The misuse of benzodiazepines as new psychoactive substances is an increasing problem around the world. Basic physicochemical and pharmacokinetic data is required on these substances to interpret and predict their effects upon humans. Experimental log D , pK and plasma protein binding values were determined for 11 benzodiazepines that have recently appeared as new psychoactive substances (3-hydroxyphenazepam, 4'-chlorodiazepam, desalkylflurazepam, deschloroetizolam, diclazepam, etizolam, flubromazepam, flubromazolam, meclonazepam, phenazepam, and pyrazolam) and compared with values generated by various software packages (ACD/I-lab, MarvinSketch, ADMET Predictor and PreADMET). ACD/I-LAB returned the most accurate values for log D and plasma protein binding while ADMET Predictor returned the most accurate values for pK . Large variations in predictive errors were observed between compounds. Experimental values are currently preferable and desirable as they may aid with the future 'training' of predictive models for these new psychoactive substances.

Section: Introductionmentioning

confidence: 99%

Experimental versus theoretical log D_7.4, pK_a and plasma protein binding values for benzodiazepines appearing as new psychoactive substances

Manchester

Maskell

Waters

2018

“…NMR spectra, recorded in CDCl 3 have previously been reported for clonazolam (7a) and nitrazolam (7b) 15,16. 3.45 Å) and CH…N π (C4…N13 triazole, ca.…”

mentioning

confidence: 90%

“…Hydrogen atoms were assigned to calculated positions using a riding model with appro- This investigation describes a novel approach for preparing NPS reference standards using a microscale synthesis procedure and polymer-supported reagents. [10][11][12]15,16 The quantitative analysis of clonazolam tablet samples (reported to contain 0.5 mg), using the synthesized material as a reference standard, yielded a value of 0.52 mg clonazolam per tablet (Supporting Information 5). In addition, both clonazolam and nitrazolam were synthesized on a preparative scale using methods that have previously been described in the literature.…”

Section: X-ray Crystallography For Clonazolammentioning

confidence: 99%

An approach to shortening the timeframe between the emergence of new compounds on the drugs market and the availability of reference standards: The microscale syntheses of nitrazolam and clonazolam for use as reference materials, utilizing polymer‐supported reagents

Dowling

Kavanagh

Eckhardt³

et al. 2018

Nitrazolam and clonazolam are 2 designer benzodiazepines available from Internet retailers. There is growing evidence suggesting that such compounds have the potential to cause severe adverse events. Information about tolerability in humans is scarce but typically, low doses can be difficult to administer for users when handling bulk material. Variability of the active ingredient in tablet formulations can also be of a concern. Customs, toxicology and forensic laboratories are increasingly encountering designer benzodiazepines, both in tablet and powdered form. The unavailability of reference standards can impact on the ability to identify these compounds. Therefore, the need arises for exploring in-house approaches to the preparation of new psychoactive substances (NPS) that can be carried out in a timely manner. The present study was triggered when samples of clonazolam were received in powdered and tablet form at a time when reference material for this drug was commercially unavailable. Therefore, microscale syntheses of clonazolam and its deschloro analog nitrazolam were developed utilizing polymer-supported reagents starting from 2-amino-2'-chloro-5-nitrobenzophenone (clonazolam) and 2-amino-5-nitrobenzophenone (nitrazolam). The final reaction step forming the 1,2,4-triazole ring moiety was performed within a gas chromatography-mass spectrometry (GC-MS) injector. A comparison with a preparative scale synthesis of both benzodiazepine derivatives showed that microscale synthesis might be an attractive option for a forensic laboratory in terms of time and cost savings when compared with traditional methods of synthesis and when qualitative identifications are needed to direct forensic casework. The reaction by-product profiles for both the micro and the preparative scale syntheses are also presented.

“…1 Since the appearance of pyrazolam on the drug market in 2012, 2 internet shops continue to offer either modifications of popular, licensed benzodiazepines or metabolites thereof. 4,5 Appearance of highly potent triazolo-compounds such as flubromazolam as pure powder may lead to the abuse of such compounds in a drug-facilitated crime context and can easily lead to severe intoxications due to dosing errors. 3 In particular, offer of metabolites [eg, norflunitrazepam ('fonazepam') and 3-hydroxyphenazepam] or designer benzodiazepines metabolizing to licensed benzodiazepines (eg, diclazepam and cloniprazepam) pose challenges for correct interpretation of analytical findings.…”

Section: Introductionmentioning

confidence: 99%

“…5,17 In The second compound investigated in this study was 4′chlorodiazepam (Ro5-4864) (7-chloro-5-(4-chlorophenyl)-1-methyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one) which is a positional isomer of the designer benzodiazepine diclazepam (Ro5-3448, 2′chlorodiazepam). 5,17 In The second compound investigated in this study was 4′chlorodiazepam (Ro5-4864) (7-chloro-5-(4-chlorophenyl)-1-methyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one) which is a positional isomer of the designer benzodiazepine diclazepam (Ro5-3448, 2′chlorodiazepam).…”

Section: Introductionmentioning

confidence: 99%

Characterization and in vitro phase I microsomal metabolism of designer benzodiazepines: An update comprising flunitrazolam, norflurazepam, and 4'‐chlorodiazepam (Ro5–4864)

Moosmann

Bisel

Westphal³

et al. 2019

Self Cite

The number of newly appearing benzodiazepine derivatives on the new psychoactive substances (NPS) drug market has increased over the last couple of years totaling 23 'designer benzodiazepines' monitored at the end of 2017 by the European Monitoring Centre for Drugs and Drug Addiction. In the present study, three benzodiazepines [flunitrazolam, norflurazepam, and 4′-chlorodiazepam (Ro5-4864)] offered as 'research chemicals' on the Internet were characterized and their main in vitro phase I metabolites tentatively identified after incubation with pooled human liver microsomes. For all compounds, the structural formula declared by the vendor was confirmed by gas chromatography−mass spectrometry (GC-MS), liquid chromatography−tandem mass spectrometry (LC MS/MS), liquid chromatography−quadrupole time of flight−mass spectrometry (LC−QTOF−MS) analysis and nuclear magnetic resonance (NMR) spectroscopy. The metabolic steps of flunitrazolam were monohydroxylation, dihydroxylation, and reduction of the nitro function. The detected in vitro phase I metabolites of norflurazepam were hydroxynorflurazepam and dihydroxynorflurazepam. 4'-Chlorodiazepam biotransformation consisted of N-dealkylation and hydroxylation. It has to be noted that 4′-chlorodiazepam and its metabolites show almost identical LC-MS/MS fragmentation patterns to diclazepam and its metabolites (delorazepam, lormetazepam, and lorazepam), making a sufficient chromatographic separation inevitable. Sale of norflurazepam, the metabolite of the prescribed benzodiazepines flurazepam and fludiazepam, presents the risk of incorrect interpretation of analytical findings.