Death after smoking of fentanyl, 5F-ADB, 5F-MDMB-P7AICA and other synthetic cannabinoids with a bucket bong

PURPOSE

We report a case of a polydrug user who consumed various synthetic cannabinoids and fentanyl from a transdermal patch via a bucket bong. Toxicological results from postmortem matrices with special focus on synthetic cannabinoids are discussed in terms of their relevance to the death.

METHODS

The samples were analyzed by toxicological screening procedures involving immunoassays and gas chromatography-mass spectrometry (GC-MS) as well as quantitative analyses by means of GC-MS and high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

At the autopsy, coronary artery disease and signs of liver congestion were noted, in the absence of acute myocardial ischemic changes. Femoral blood concentrations of fentanyl and pregabalin were 14 ng/mL and 3,200 ng/mL, respectively. In addition, 2.7 ng/mL 5F-ADB and 13 ng/mL 5F-MDMB-P7AICA were detected together with relatively low amounts of 5 other synthetic cannabinoids in cardiac blood. A total number of up to 17 synthetic cannabinoids were detected in kidney, liver, urine and hair. Fentanyl and 5F-ADB were also detected in the water of the bucket bong.

CONCLUSIONS

The cause of death could be attributed to an acute mixed intoxication by fentanyl and 5F-ADB (both Toxicological Significance Score (TSS) = 3) with a contribution of pregabalin and 5F-MDMB-P7AICA (TSS = 2), in a subject suffering from pre-existing heart damage. The most plausible mechanism of death consists in a respiratory depression. This case report demonstrates that use of opioids in combination with synthetic cannabinoids might be particularly dangerous.

Rapid determination of plasma vigabatrin by LC-ESI-MS/MS supporting therapeutic drug monitoring in children with infantile spasms

Vigabatrin is one of the second-generation anti-seizure medications (ASMs) designated orphan drugs by the FDA for monotherapy for pediatric patients with infantile spasms from 1 month to 2 years of age. Vigabatrin is also indicated as the adjunctive therapy for adults and pediatric patients 10 years of age and older with refractory complex partial seizures. Ideally, the vigabatrin treatment entails achieving complete seizure freedom without significant adverse effects, and the therapeutic drug monitoring (TDM) will make a significant contribution to this aim, which provides a pragmatic approach to such epilepsy care in that the dose tailoring can be undertaken for uncontrollable seizures and in cases of clinical toxicity guided by the drug concentrations. Thus, reliable assays are mandatory for TDM to be valuable, and blood, plasma, or serum are the matrixes of choice. In this study, a simple, rapid, and sensitive LC-ESI-MS/MS method for the measurement of plasma vigabatrin was developed and validated. The sample clean-up was performed by an easy-to-use method, i.e., protein precipitation using acetonitrile (ACN). Chromatographic separation of vigabatrin and vigabatrin-¹³C,d₂ (internal standard) was achieved on the Waters symmetry C18 column (4.6 mm × 50 mm, 3.5 μm) with isocratic elution at a flow rate of 0.35 mL min^-1. The target analyte was completely separated by elution with a highly aqueous mobile phase for 5 min, without any endogenous interference. The method showed good linearity over the 0.010-50.0 μg mL^-1 concentration range with a correlation coefficient r² = 0.9982. The intra-batch and inter-batch precision and accuracy, recovery, and stability of the method were all within the acceptable parameters. Moreover, the method was successfully used in pediatric patients treated with vigabatrin and also provided valuable information for clinicians by monitoring plasma vigabatrin levels in our hospital.

Derivatization of γ-Amino Butyric Acid Analogues for Their Determination in the Biological Samples and Pharmaceutical Preparations: A Comprehensive Review

γ-Aminobutyric acid (GABA) plays an important role in regulating neuronal excitability. Four structurally related drugs to GABA including pregabalin (PGB), gabapentin (GBP), vigabatrin (VGB), and baclofen are used for the treatment of central nervous system disorders. These drugs are small aliphatic molecules having neither fluorescent nor strong absorbance in the ultraviolet/visible region; therefore, direct determination of these analytes by optical methods is difficult. Additionally, their high boiling point makes gas chromatography impossible. Accordingly, the amine or acid moiety in these drugs is derivatized in order to improve their selectivity and sensitivity during determination in the biological samples. This review focuses on derivatization based methods and their different reactions for determination of PGB, GBP, VGB, and baclofen in the biological samples and pharmaceutical preparations reported between 1980 and 2020. High-performance liquid chromatography methods coupled with different detectors are a commonly used methods for determination of GABA analogs after derivatization. These methods cover 38.89% of all developed methods for determination of GABA analogs.

Determination of three antiepileptic drugs in pharmaceutical formulations using microfluidic chips coupled with light-emitting diode induced fluorescence detection

In this study, a facile, sensitive, and precise lab-on-a-chip electrophoretic method coupled with light-emitting diode induced fluorescence (LED-IF) detection was developed to assay three antiepileptic drugs, namely, vigabatrin, pregabalin, and gabapentin, in pharmaceutical formulations. The analytes were derivatised offline for the first time with fluorescine-5-isothiocyanate (FITC) to yield highly fluorescent derivatives with λ_ex/em of 490/520nm. The FITC-labelled analytes were injected, separated, and quantitated by a microfluidic electrophoresis device using fluorescence detection. The labelled analytes were monitored using a blue LED-IF system. The separation conditions were significantly optimised adding specific concentrations of heptakis-(2,6-di-O-methyl)-β-cyclodextrin (HDM-β-CD) and methylcellulose to the buffer solution (40mM borate buffer). HDM-β-CD acted as a selective host for the studied antiepileptic drugs, rendering a high separation efficiency. Methylcellulose was used as an efficient dynamic coating polymer to prevent the labelled drugs from being adsorbed on the inner surfaces of the poly (methylmethacrylate) microchannels. A laboratory-prepared ternary mixture of the three antiepileptic drugs was separated within 100s with acceptable resolution between all the three analytes (R_s>3) and a high number of theoretical plates (N) for each analyte (N≈10⁶ plates/m). The sensitivity of the method was enhanced approximately 80-fold by stacking to yield a detection limit below 0.6ngmL^-1 in the concentration range of 2.0-200.0ngmL^-1. The method was successfully validated for analysing the studied drugs in their pharmaceutical formulations.

A Critical Review on Analytical Methods for Recently Approved FDC Drugs: Pregabalin and Etoricoxib

Fixed-dose combinations (FDCs) refer to products containing two or more active ingredients combined in a single dosage form. The FDCs are justified because of several advantages. These are a) potentiating therapeutic efficacy, b) reducing the incidences of adverse drug effects, c) having pharmacokinetic advantages, d) reducing pills burden, e) reducing the dose of individual drugs and f) decreasing the drug resistance development. A recently approved FDC of Pregabalin IP (75 mg) and Etoricoxib (60 mg) recommended to control neuropathic chronic back pain. Analytical methods are available for individual quantitation of pregabalin (PGB) and etoricoxib (ETC), but an effective and reliable analytical method has not been reported for their combination. Thus, the objective of this literature survey was to gather information on various analytical instrumental methods used so far for the individual quantitation of PGB and ETC in various matrices. Such data would be useful to the scientific community to develop a novel analytical method for the analysis of recently approved FDC of PGB and ETC. Various scientific databases were explored to meet the objectives, and the information is synchronized. The reported methods are high-performance liquid chromatography (48% & 53%), hyphenated techniques (54% & 21%), spectroscopy (50% & 34%), and high-performance thin-layer chromatography, or thin-layer chromatography (6% & 13%) for pregabalin and etoricoxib, respectively. All these methods were specific and selective for the analysis of individual drugs.

Large volume sample stacking of antiepileptic drugs in counter current electrophoresis performed in PAMAPTAC coated capillary

Electrophoretic stacking is developed for sensitive determination of three zwitterionic antiepileptics, namely vigabatrin, pregabalin and gabapentin, in human serum. CE separation is performed in a 25 μm fused silica capillary covalently coated with the copolymer of acrylamide with 5% content of permanently charged 3-acrylamidopropyl trimethylammonium chloride (PAMAPTAC). In background electrolyte of 500 mM acetic acid, the 5% PAMAPTAC generates an anodic electro-osmotic flow with a magnitude of (-18.6 ± 0.5) · 10^-9 m²V^-1s^-1, which acts against the direction of the electrophoretic migration of the analytes. A sample of the antiepileptic prepared in a 25% v/v infusion solution and 75% v/v acetonitrile is injected into the capillary in a large volume attaining a zone length of up to 270 mm. After turning on the separation voltage, the antiepileptics are isotachophoretically focussed behind the zone of Na⁺ ions with a sensitivity enhancement factor of 78. For the clinical determination of antiepileptics, the human serum is diluted with acetonitrile in a ratio of 1:3 v/v and a zone with a length of 90 mm is injected into the capillary. The method is linear in the 0.025-2.5 μg/mL concentration range; the attained limit of quantification is in the range 18.3-22.8 nmol/L; the within-day precision for the migration time is 0.8-1.2% and for the peak area 1.5-2.4%.

Simple mix-and-read assays for the determination of baclofen in pharmaceutical formulation

This study demonstrates three simple and inexpensive spectrophotometric mix-and-read assays for the determination of the skeletal muscle relaxant, baclofen (BAC) in pharmaceutical formulations. The proposed methods are based on the reaction of the primary amine group of BAC with various derivatizing reagents to yield different colored products. Method I depends on the reaction of BAC with vanillin in borate buffer pH 11.5 to give a yellow colored product with maximum absorbance at 401 nm. While method II describes the reaction with eosin Y in citric-phosphate buffer pH 2.2 forming an orange-red product measured at 548 nm. Method III depends on Hantzsch condensation reaction that yields a yellow product measured at 339 nm. Different experimental variables influencing development and stability of the obtained colored product are optimized. Validation of the three methods regarding linearity, ranges, precision, accuracy and limits of detection and quantification was performed. Regression analysis showed good linearity over the concentration ranges of 10-35, 5-20 and 5-25 μg/mL for methods I, II and III, respectively with correlation coefficient values not less than 0.999. Additionally, detection limits of BAC are 1.58, 0.94 and 0.79 μg/mL for methods I, II and III, respectively. Finally, the suggested procedures are successfully used for assay of BAC in its tablets. The main advantages of the proposed mix-and-read assays are being inexpensive and rapid with no requirement for laborious extraction techniques with equivalent or superior sensitivity compared to other published spectrophotometric procedures. Such advantages promote the suggested methods for the high throughput assay of BAC dosage forms, a critical component in quality control studies for pharmaceutical industries.

Determination of baclofen and vigabatrin by microchip electrophoresis with fluorescence detection: application of field-enhanced sample stacking and dynamic pH junction

A novel microchip gel electrophoretic method for the assay of baclofen and vigabatrin for the first time.

A Validated Fluorometric Method for the Rapid Determination of Pregabalin in Human Plasma Applied to Patients With Pain

BACKGROUND

Pregabalin has been used for the treatment of pain. A clinically accepted method applied to patients with pain has not been published for the determination of pregabalin in human plasma. This study developed a fluorometric ultrahigh-performance liquid chromatography (UHPLC) method to measure pregabalin concentration in patients with pain.

METHODS

After plasma pretreatment involving protein precipitation, pregabalin and gabapentin as an internal standard were derivatized with 4-fluoro-7-nitrobenzofurazan (NBD-F) under the following reaction conditions: 1 minute, pH 10, and 60°C. The UHPLC separation was performed using a 2.3-μm particle size octadecylsilyl column. The fluorescence detector was set at excitation and emission wavelengths of 470 and 530 nm, respectively. The predose blood samples were collected from 40 patients with pain who have been treated with 75 mg of pregabalin twice daily.

RESULTS

The chromatographic run time was 1.25 minutes. No interfering peaks were observed in the blank plasma at the retention times of NBD derivatives. The calibration curve of pregabalin was linear at a range of 0.05-10 mcg/mL (r > 0.999). The lower limit of quantification was 0.05 mcg/mL. The intra-assay accuracy and precision were 98.3%-99.8% and within 4.3%, respectively. The inter-assay accuracy and precision were 103.2%-107.1% and within 4.1%, respectively. The predose plasma concentration of pregabalin in patients with pain ranged from 0.14 to 8.5 mcg/mL.

CONCLUSIONS

This study provides a validated fluorometric UHPLC method with fast analytical performance for the determination of pregabalin in human plasma. The present method could be applied to patients with pain and be used for the clinical research or therapeutic drug monitoring of pregabalin.

Gabapentin, Pregabalin and Vigabatrin Quantification in Human Serum by GC-MS After Hexyl Chloroformate Derivatization

A simple, sensitive and robust method for simultaneous determination of antiepileptic drugs (gabapentin, pregabalin and vigabatrin) in human serum using GC-MS was developed and validated for clinical toxicology purposes. This method employs an emerging class of derivatization agents - alkyl chloroformates allowing the efficient and rapid derivatization of both the amino and carboxylic groups of the tested antiepileptic drugs within seconds. The derivatization protocol was optimized using the Design of Experiment statistical methodology, and the entire sample preparation requires less than 5 min. Linear calibration curves were obtained in the concentration range from 0.5 to 50.0 mg/L, with adequate accuracy (97.9-109.3%) and precision (<12.1%). The method was successfully applied to quantification of selected γ-aminobutyric acid analogs in the serum of patients in both therapeutic and toxic concentration ranges.

Targeted toxicological screening for acidic, neutral and basic substances in postmortem and antemortem whole blood using simple protein precipitation and UPLC-HR-TOF-MS

A broad targeted screening method based on broadband collision-induced dissociation (bbCID) ultra-performance liquid chromatography high-resolution time-of-flight mass spectrometry (UPLC-HR-TOF-MS) was developed and evaluated for toxicological screening of whole blood samples. The acidic, neutral and basic substances covered by the method were identified in postmortem and antemortem whole blood samples from forensic autopsy cases, clinical forensic cases and driving under the influence of drugs (DUID) cases by a reverse target database search. The screening method covered 467 substances. Validation was performed on spiked whole blood samples and authentic postmortem and antemortem whole blood samples. For most of the basic drugs, the established cut-off limits were very low, ranging from 0.25ng/g to 50ng/g. The established cut-off limits for most neutral and acidic drugs, were in the range from 50ng/g to 500ng/g. Sample preparation was performed using simple protein precipitation of 300μL of whole blood with acetonitrile and methanol. Ten microliters of the reconstituted extract were injected and separated within a 13.5min UPLC gradient reverse-phase run. Positive electrospray ionization (ESI) was used to generate the ions in the m/z range of 50-1000. Fragment ions were generated by bbCID. Identification was based on retention time, accurate mass, fragment ion(s) and isotopic pattern. A very sensitive broad toxicological screening method using positive electrospray ionization UPLC-HR-TOF-MS was achieved in one injection. This method covered basic substances, substances traditionally analyzed in negative ESI (e.g., salicylic acid), small highly polar substances such as beta- and gamma-hydroxybutyric acid (BHB and GHB, respectively) and highly non-polar substances such as amiodarone. The new method was shown to combine high sensitivity with a very broad scope that has not previously been reported in toxicological whole blood screening when using only one injection.

Application of high-resolution mass spectrometry to determination of baclofen in a case of fatal intoxication

The study focused on the application of high-resolution mass spectrometry (HRMS) to postmortem toxicological analysis. Fast and simple sample preparation involved precipitation with acetonitrile, removal of phospholipids using special columns and filtration. Qualitative and quantitative analyses were performed using ultra-performance liquid chromatography coupled with quadrupole time-of–flight mass spectrometry. The method was validated by determining the limit of quantification, precision, recovery and matrix effect. The use of a high-resolution spectrometer allowed us to determine the precise masses of the fragments of interest and to suggest the fragmentation pathway of baclofen. The usefulness, effectiveness and assets of the procedure were confirmed by an authentic case of a 25-year-old woman fatally intoxicated with baclofen who was found dead in her apartment. Toxicological analysis of postmortem blood samples demonstrated that the baclofen concentration was 30.7 μg/mL. In only one published case describing fatal baclofen intoxication were no other xenobiotics (that could interact with baclofen) found. To our knowledge, this is the first report dealing with analysis of baclofen by HRMS.

Validated Method for the Quantification of Baclofen in Human Plasma Using Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry

A highly sensitive and fully validated method was developed for the quantification of baclofen in human plasma. After adjusting the pH of the plasma samples using a phosphate buffer solution (pH 4), baclofen was purified using mixed mode (C8/cation exchange) solid-phase extraction (SPE) cartridges. Endogenous water-soluble compounds and lipids were removed from the cartridges before the samples were eluted and concentrated. The samples were analyzed using triple-quadrupole liquid chromatography-tandem mass spectrometry (LC-MS-MS) with triggered dynamic multiple reaction monitoring mode for simultaneous quantification and confirmation. The assay was linear from 25 to 1,000 ng/mL (r(2) > 0.999; n = 6). Intraday (n = 6) and interday (n = 15) imprecisions (% relative standard deviation) were <5%, and the average recovery was 30%. The limit of detection of the method was 5 ng/mL, and the limit of quantification was 25 ng/mL. Plasma samples from healthy male volunteers (n = 9, median age: 22) given two single oral doses of baclofen (10 and 60 mg) on nonconsecutive days were analyzed to demonstrate method applicability.