Human metabolism and basic pharmacokinetic evaluation of AP-238: A recently emerged acylpiperazine opioid

As a consequence of recently implemented legal restrictions on fentanyl analogs, a new generation of acylpiperazine opioids appeared on the illicit drug market. AP-238 was the latest opioid in this series to be notified by the European Early Warning System in 2020 and was involved in an increasing number of acute intoxications. AP-238 metabolism was investigated to provide useful markers of consumption. For the tentative identification of the main phase I metabolites, a pooled human liver microsome assay was performed. Further, four whole blood and two urine samples collected during post-mortem examinations and samples from a controlled oral self-administration study were screened for anticipated metabolites. In total, 12 AP-238 phase I metabolites were identified through liquid chromatography-quadrupole time-of-flight mass spectrometry in the in vitro assay. All of these were confirmed in vivo, and additionally, 15 phase I and five phase II metabolites were detected in the human urine samples, adding up to a total of 32 metabolites. Most of these metabolites were also detected in the blood samples, although mostly with lower abundances. The main in vivo metabolites were built by hydroxylation combined with further metabolic reactions such as O-methylation or N-deacylation. The controlled oral self-administration allowed us to confirm the usefulness of these metabolites as proof of intake in abstinence control. The detection of metabolites is often crucial to documenting consumption, especially when small traces of the parent drug can be found in real samples. The in vitro assay proved to be suitable for the prediction of valid biomarkers of novel synthetic opioid intake.

Optimization of experimental conditions by surface enhanced Raman Scattering (SERS) spectroscopy with gold nanoparticles suspensions

Surface Enhanced Raman Scattering (SERS) spectroscopy is a rapid and innovative analysis technique involving metallic nanoparticles (NPs). The interaction between NPs and norepinephrine gives an exaltation of the Raman signal under certain experimental conditions. The control of the signal exaltation, crucial for sensitive analyses, remains one of the main limitations of this technique. The aim of this work is to optimize the exaltation conditions for an optimal SERS signal at two concentrations of norepinephrine (NOR) and spherical gold NPs in suspension. This first work will fix the optimal experimental conditions essential for the development of robust discriminant and quantitative analysis of catecholamine. Two complete 3-factors 3-levels experiment designs were performed at 20 µg.mL^-1 and 100 µg.mL^-1 norepinephrine concentrations, each experiment being repeated 3 times. The optimization factors were the process of synthesis (variation of the quantity of gold and citrate used for the three synthesis SA, SB and SC) and HCl (0.3 M, 0.5 M, 0.7 M) as well as the volume ratio of NPs and norepinephrine (0.5, 2, 3.5) for SERS acquisition. Spectral acquisitions were performed with a handheld Raman spectrometer with an excitation source at 785 nm. For each sample, 31 acquisitions were realized during 3 s every 8 s. The optimization parameter was the intensity of the characteristic band of norepinephrine at 1280 cm^-1. A total of 5,042 spectra were acquired and the pre-treatment selected for all spectra was asymmetric least square combined to a smoothing of Savistsky Golay (ALS - SG). The optimal contact time between norepinephrine and NPs depends on the experimental conditions and was determined for each experiment according to the mean intensity between the three replicates. After interpretation of the experimental designs, the optimal conditions retained were the quantity of gold corresponding to SA and the HCl concentration 0.7 M for the two concentrations of norepinephrine. Indeed, the optimal volume ratio depend on the NOR concentration.

Detection of Soluble Mercury in Cinnabar Using a CV-Ag NPs SERS Probe

In the current work a uniform morphological Ag nanoparticles (Ag NPs) were prepared with ascorbic acid as a reducing agent and citrate as a stabilizer. The surface of Ag NPs modified by crystal violet (CV) and potassium iodide (KI) was used as an aggregation agent to obtain CV modified Ag NPs (CV-Ag NPs) probes for detecting mercury ions. The mercury ions could be reduced to mercury molecules by citrate, and then deposited on the surface of Ag NPs, leading to the separation of CV molecules from the surface of Ag NPs. Therefore, the SERS signal intensity of CV decreased with the increase of the Hg²⁺ concentration and the concentration of Hg²⁺ was in the range of 1 × 10^-11 to 1 × 10^-5 M. Taking the change of the characteristic peak intensity of CV at 913 cm^-1 as a reference, the SERS spectrum intensity of CV has a linear relationship with the Hg²⁺ concentration. The equation is y = -333.55x + 1343.05, where the linear correlation coefficient is R² = 0.980, and the recovery rate is between 84.20 to 105.60%. Finally, the CV-Ag NPs probe was used to quickly detect soluble mercury in cinnabar. Compared with the conventional large-scale instrument detection method, this simple and fast method, can be applied for rapid detection of soluble mercury, and has a certain significance for concerning the research of mineral medicine processing mechanism.

DARK Classics in Chemical Neuroscience: Bucinnazine

Bucinnazine (1-butyryl-4-cinnamylpiperazine) is a synthetic opioid recently discovered in heroin seized samples in the U.S and in Europe. It was first synthesized in the late 1960s and has been used for the treatment of cancer-associated chronic pain in China for many years. Bucinnazine is one of the most potent compounds among the series of piperazines, which also include other relevant compounds, such as MT-45, AD-1211, and 2-methyl-AP-237, a methylated derivative of bucinnazine. Bucinnazine is considered a μ-selective opioid, binding primarily to the μ-opioid receptor. However, bucinnazine also may share several characteristics with other piperazines, which act primarily on dopamine, serotonin, and norepinephrine neurotransmission. At the present, bucinnazine is not scheduled in the U.S., as it is not a therapeutic choice for the treatment of pain. Nevertheless, with the advent of the cryptocurrency and the easy access of substances on the Darknet, bucinnazine is a real threat to the public health. This review discusses the main aspects of bucinnazine's chemistry, pharmacology, and toxicology and brings attention to the risk of the presence of this opioid in seized samples. Further studies on bucinnazine are still required to better evaluate its toxicity mechanisms, potential for drug-drug interactions, and abuse liability. Such information will be of utmost importance to guide future policies concerning the legal status of bucinnazine in the U.S.

Rapid Detection of Dezocine in Biological Fluids Based on SERS Technology

This paper describes a method based on surface enhanced Raman spectroscopy (SERS) technology for rapid detection of dezocine in urine and serum. Firstly, an Ag colloid substrate was prepared and characterized. Then the Raman characteristic peaks of dezocine were assigned from both theoretical and experimental aspects. Finally, the Raman peak at 661 cm^-1 was selected as its characteristic peak to perform SERS detection on dezocine in urine and serum, and the detection limits of dezocine in urine and serum were determined. The relationships between the characteristic peak intensity and the concentration of dezocine in urine and serum were fitted and the recovery rates were calculated. This rapid, accurate and non-destructive method establishes a good foundation for rapid on-site detection of dezocine in biological samples.

A Rapid Detection Method for On-site Screening of Estazolam in Beverages with Au@Ag Core-shell Nanoparticles Paper-based SERS Substrate

Estazolam (EST) is a common sedative-hypnotic drug with a risk of abuse. Therefore, rapid on-site detection of EST is necessary to control the abuse of EST. In this paper, a fast, simple, and sensitive method is demonstrated for the detection of EST in both water and beverages, using surface-enhanced Raman spectroscopy (SERS) techniques. Au@Ag core-shell nanoparticles (NPs) assembled on the filter paper as a SERS substrate exhibit good applicability and practicality. At the same time, density functional theory (DFT) is used to assign the vibration mode of the EST molecules, which can be used as a guide for subsequent experiments. The lowest detectable concentration of EST in aqueous solution can be as low as 5 mg/L, and signal uniformity is excellent (RSD687 = 5.56%, RSD1000 = 4.35%). In addition, EST components artificially added to orange juice and pomegranate juice can be effectively detected by simple pretreatment with a minimum detection concentration as low as 10 mg/L. Therefore, this study found that the use of Au@Ag core-shell nanoparticles paper-based SERS substrate provides a quick and easy method for the detection of illegally added drugs in beverages.