Autoradiographic study on the pharmacological characteristics of [3H]3-OH-PCP binding sites in rat brain

In vitro and in vivo metabolism and detection of 3-HO-PCP, a synthetic phencyclidine, in human samples and pooled human hepatocytes using high resolution mass spectrometry

The new psychoactive substance (NPS) 3-HO-PCP, a phencyclidine (PCP) analog, was detected in a law enforcement seizure and in forensic samples in Denmark. Compared with PCP, 3-HO-PCP is known to be a more potent dissociative NPS, but no toxicokinetic investigations of 3-HO-PCP are yet available. Therefore, 3-HO-PCP was quantified in in vivo samples, and the following were investigated: plasma protein binding, in vitro and in vivo metabolites, and metabolic targets. All samples were separated by liquid chromatography and analyzed by mass spectrometry. The unbound fraction in plasma was determined as 0.72 ± 0.09. After in vitro incubation with pooled human hepatocytes, four metabolites were identified: a piperidine-hydroxyl-and piperidine ring opened N-dealkyl-COOH metabolite, and O-glucuronidated- and O-sulfate-conjugated metabolites. In vivo, depending on the sample and sample preparation, fewer metabolites were detected, as the O-sulfate-conjugated metabolite was not detected. The N-dealkylated-COOH metabolite was the main metabolite in the deconjugated urine sample. in vivo analytical targets in blood and brain samples were 3-HO-PCP and the O-glucuronidated metabolite, with 3-HO-PCP having the highest relative signal intensity. The drug levels of 3-HO-PCP quantified in blood were 0.013 and 0.095 mg/kg in a living and a deceased subject, respectively. The 3-HO-PCP concentrations in deconjugated urine in a sample from a living subject and in post-mortem brain were 7.8 and 0.16 mg/kg, respectively. The post mortem results showed a 1.5-fold higher concentration of 3-HO-PCP in the brain tissue than in the post mortem blood sample.

Severe Toxicity to the New Psychoactive Substances 3-Hydroxyphencyclidine and N-Ethylhexedrone: an Analytically Confirmed Case Report

INTRODUCTION

3-Hydroxyphencyclidine (3-HO-PCP) is a new psychoactive substance (NPS) and a hydroxy derivative of phencyclidine (PCP), and N-ethylhexedrone (Hexen) is a synthetic cathinone. We describe an analytically confirmed case of acute toxicity related to the use of both 3-hydroxyphencyclidine and N-ethylhexedrone.

CASE REPORT

A 56-year-old male was brought to the Emergency Department by ambulance with hyperthermia (39.9 °C), sinus tachycardia (150 beats per minute), reduced consciousness, ocular clonus, and vertical nystagmus. He was treated with cooled intravenous (IV) fluids and IV benzodiazepines. Following 1 hour of treatment, his temperature fell to 37.7 °C, he developed rhabdomyolysis (creatine kinase peaked at 5999 IU (normal range < 229 IU)): he was managed with supportive measures and was discharged after 25 hours. The patient admitted regular use of Hexen and recent use of 3-HO-PCP. Analysis of urine and serum identified 3-hydroxyphencyclidine and metabolites, N-ethylhexedrone and metabolites, and clephedrone and metabolites.

DISCUSSION

This is a case of analytically confirmed toxicity to 3-HO-PCP and N-ethylhexedrone. The acute toxicity reported in this patient is consistent with the use of 3-HO-PCP, but there were sympathomimetic and serotonergic features potentially consistent with the cathinone N-ethylhexedrone. The description of the acute toxicity of NPS, such as these, is vital to aid medical toxicologists and emergency medicine physicians treating patients who use them.

Phencyclidine-Based New Psychoactive Substances

The serendipitous discovery of phencyclidine (PCP) in 1956 sets the stage for significant research efforts that resulted in a plethora of analogs and derivatives designed to explore the biological effects of this class. PCP soon became the prototypical dissociative agent that eventually sneaked through the doors of clinical laboratories and became an established street drug. Estimations suggest that around 14 PCP analogs were identified as "street drugs" in the period between the 1960s and 1990s. Fast forward to the 2000s, and largely facilitated by advancements in electronic forms of communication made possible through the Internet, a variety of new PCP analogs began to attract the attention of communities interested in the collaborative exploration of these substances. Traditionally, as was the case with the first-generation analogs identified in previous decades, the substances explored represented compounds already known in the scientific literature. As the decade of the noughties unfolded, a number of new PCP-derived substances appeared on the scene, which included some analogs that have not been previously recorded in the published literature. The aim of this chapter is to present a brief introductory overview of substances that have materialized as PCP-derived new psychoactive substances (NPS) in recent years and their known pharmacology. Since N-methyl-D-aspartate receptor (NMDAR) antagonism is implicated in mediating the subjective and mind-altering effects of many dissociative drugs, additional data are included from other analogs not presently identified as NPS.

NMDA and opioid receptors: their interactions in antinociception, tolerance and neuroplasticity

Over the last several years, significant progress has been made in our understanding of interactions between the N-methyl-D-aspartate (NMDA) and opioid receptors. Such interactions have been demonstrated at two distinct sites: (1) modulation of NMDA receptor-mediated electrophysiological events by opioids; and (2) intracellular events involving interactions between NMDA and opioid receptors. Furthermore, a considerable number of studies have shown the involvement of such interactions in neural mechanisms of nociceptive transmission, antinociception in acute and chronic pain states, opioid tolerance/dependence, and neuroplasticity. Importantly, emerging evidence indicates that activation of NMDA receptors may differentially modulate functions mediated by distinct opioid receptor subtypes, namely mu, delta, and kappa receptors. These studies have greatly enriched our knowledge regarding both NMDA and opioid receptor systems and have shed light on neurobiology of both acute and chronic pain. The advancement of such knowledge also promotes new strategies for better clinical management of pain patients.