Loperamide positive deaths in Sweden 2012-2022 and Finland 2017-2022: Fatal loperamide intoxication exclusively for Sweden

Loperamide, a potent μ-opioid receptor agonist used as an antidiarrheal drug, exhibits increased bioavailability at supratherapeutic doses, causing potential central nervous system effects. Its misuse for opioid withdrawal relief and euphoria can lead to dangerously elevated blood levels, causing severe cardiac dysrhythmias and death. This study aimed to compare loperamide positive autopsy cases in Sweden and Finland after the introduction of postmortem toxicological analysis of loperamide, focusing on loperamide's role in fatalities and identifying common characteristics among those affected. All cases with detected loperamide in femoral blood at forensic autopsies in Sweden (2012-2022) and Finland (2017-2022) were included. In Sweden, loperamide was detected in 126 individuals, and in Finland, in 111 individuals. The incidence of individuals positive for loperamide in postmortem femoral blood increased steadily over the study duration in both Sweden and Finland. Loperamide related fatalities were observed exclusively in Sweden (n=80), predominantly involving younger males with histories of substance abuse, typically classified as accidental deaths. The group of loperamide nonrelated deaths in Sweden mirrored the entirety of cases in Finland. The concentration of loperamide in postmortem femoral blood was significantly higher in cases where loperamide was considered the cause of death (median 0.140 μg/g) compared to cases where loperamide contributed (median 0.080 μg/g), as well as in deaths unrelated to loperamide in both countries (Sweden: median 0.029 μg/g; Finland: median 0.010 μg/ml). The high limit of quantification for loperamide in Sweden may underestimate therapeutic users in epidemiological assessments. This study underscores the absence of loperamide misuse in Finland and indicates a rising trend of loperamide abuse in Sweden.

Suspected North Carolina counterfeit pill-involved deaths, 2020-2022

The NC Office of the Chief Medical Examiner regularly assumes jurisdiction over deaths that are suspicious, unusual or unattended by a medical professional. In recent years, the presence of counterfeit pills is occasionally suggested by investigatory notes and/or scene findings that document reported consumption of prescription drugs, or prescription drugs on scene, which are not reflected in the final autopsy findings after toxicological analysis of the decedent's blood samples. Counterfeit pill consumption is a major public health hazard worthy of attention from the forensic toxicology community. Seventy-five cases from January 2020 to December 2022 serve as a convenience sample of cases where prescription pills including formulations of alprazolam, oxycodone and hydrocodone were specifically referenced during the death scene investigation as recently consumed, yet an unexpected substance was found during toxicological analysis rather than the expected pharmaceutical drug. Of note, novel benzodiazepines detected included flualprazolam, etizolam, clonazolam metabolite (8-aminoclonazolam), bromazolam, flubromazolam and desalkylflurazepam. Decedents' ages ranged from 16 to 69, across 33 different NC counties. Case notes indicated that eight of the decedents obtained pills through direct personal relationships, six decedents obtained them from "the street" and one decedent likely purchased pills online. Pills were largely consumed orally or through insufflation. Seven case reports contained indication that decedents knew or suspected the counterfeit nature of their pills. This study describes the context and characteristics of 2020-2022 suspected counterfeit pill-involved deaths in NC to further the understanding of the forensic science community, law enforcement partners, public health stakeholders and those potentially at risk through the consumption of counterfeit pills.

Relevance of pharmacogenetics and pharmacogenomics in veterinary clinical practice: A review

The recent advances in high-throughput next-generation sequencing technologies have heralded the arrival of the Big Data era. As a result, the use of pharmacogenetics in drug discovery and individualized drug therapy has transformed the field of precision medicine. This paradigm shift in drug development programs has effectively reshaped the old drug development practices, which were primarily concerned with the physiological status of patients for drug development. Pharmacogenomics bridges the gap between pharmacodynamics and pharmacokinetics, advancing current diagnostic and treatment strategies and enabling personalized and targeted drug therapy. The primary goals of pharmacogenetic studies are to improve drug efficacy and minimize toxicities, to identify novel drug targets, to estimate drug dosage for personalized medicine, and to incorporate it as a routine diagnostic for disease susceptibility. Although pharmacogenetics has numerous applications in individualized drug therapy and drug development, it is in its infancy in veterinary medicine. The objective of this review is to present an overview of historical landmarks, current developments in various animal species, challenges and future perspectives of genomics in drug development and dosage optimization for individualized medicine in veterinary subjects.

The Potential Mechanisms behind Loperamide-Induced Cardiac Arrhythmias Associated with Human Abuse and Extreme Overdose

Loperamide has been a safe and effective treatment for diarrhea for many years. However, many cases of cardiotoxicity with intentional abuse of loperamide ingestion have recently been reported. We evaluated loperamide in in vitro and in vivo cardiac safety models to understand the mechanisms for this cardiotoxicity. Loperamide slowed conduction (QRS-duration) starting at 0.3 µM [~1200-fold (×) its human Free Therapeutic Plasma Concentration; FTPC] and reduced the QT-interval and caused cardiac arrhythmias starting at 3 µM (~12,000× FTPC) in an isolated rabbit ventricular-wedge model. Loperamide also slowed conduction and elicited Type II/III A-V block in anesthetized guinea pigs at overdose exposures of 879× and 3802× FTPC. In ion-channel studies, loperamide inhibited hERG (IKr), INa, and ICa currents with IC50 values of 0.390 µM, 0.526 µM, and 4.091 µM, respectively (i.e., >1560× FTPC). Additionally, in silico trials in human ventricular action potential models based on these IC50s confirmed that loperamide has large safety margins at therapeutic exposures (≤600× FTPC) and confirmed repolarization abnormalities in the case of extreme doses of loperamide. The studies confirmed the large safety margin for the therapeutic use of loperamide but revealed that at the extreme exposure levels observed in human overdose, loperamide can cause a combination of conduction slowing and alterations in repolarization time, resulting in cardiac proarrhythmia. Loperamide's inhibition of the INa channel and hERG-mediated IKr are the most likely basis for this cardiac electrophysiological toxicity at overdose exposures. The cardiac toxic effects of loperamide at the overdoses could be aggravated by co-medication with other drug(s) causing ion channel inhibition.

Peripherally restricted transthyretin-based delivery system for probes and therapeutics avoiding opioid-related side effects

Several investigations into the sites of action of opioid analgesics have utilized peripherally acting mu-opioid receptor antagonists (PAMORAs), which have been incorrectly assumed to possess limited permeability across the blood-brain barrier. Unfortunately, the poor pharmacokinetic properties of current PAMORAs have resulted in misunderstandings of the role of central nervous system and gastrointestinal tract in precipitating side effects such as opioid-induced constipation. Here, we develop a drug delivery approach for restricting the passage of small molecules across the blood-brain barrier. This allows us to develop naloxone- and oxycodone-based conjugates that display superior potency, peripheral selectivity, pharmacokinetics, and efficacy in rats compared to other clinically used PAMORAs. These probes allow us to demonstrate that the mu-opioid receptors in the central nervous system have a fundamental role in precipitating opioid-induced constipation. Therefore, our conjugates have immediate use as pharmacological probes and potential therapeutic agents for treating constipation and other opioid-related side effects.

Melatonin Supplementation in Undetermined Pediatric Deaths

Since 2015, the North Carolina Office of the Chief Medical Examiner has investigated seven deaths of infants and toddlers, ages 2 months to 3 years, with exogenous melatonin detected upon toxicological analysis. Melatonin concentrations ranged from 3-1400 ng/mL in postmortem whole blood. While the cause and the manner of all seven deaths were classified as undetermined, the analytical findings are noteworthy. Melatonin is generally considered a safe, natural product appearing in many over-the-counter supplements geared towards young children to facilitate calmness and improve sleep. Melatonin is a neurohormone, which regulates not only circadian rhythms and natural sleep, but other physiological functions. Endogenous melatonin production, derived from essential amino acid metabolism, does not begin until pineal gland maturation at around three months of age with concentrations in plasma peaking during periods of darkness at approximately 0.2 ng/mL. Administering commercially available melatonin supplements to infants results in levels orders of magnitude greater than endogenous sources which should not be assumed to be safe just because of its endogenous nature. The finding of exogenous concentrations in some postmortem pediatric cases warrants attention. Several topics of interest surrounding these postmortem melatonin findings will be considered, such as minimal regulatory control over commercial products as well as the potential impact on hazardous sleeping conditions. This manuscript will outline the physiological effects of melatonin and detail the case studies from the NC medical examiner system. Forensic toxicology laboratories should consider including melatonin at exogenous concentrations in their testing schemes for appropriate postmortem infant and toddler cases.

Two Single Drug Fatal Intoxications By Mitragynine

Mitragyna speciosa, a species of plant that is native to Thailand, Malaysia and Southeast Asia, contains two major psychoactive alkaloids: mitragynine and 7-hydroxymitragynine. Pharmacologically, the alkaloids exhibit biphasic effects - at low dose, stimulant effects are realized, while high doses exhibit sedative effects. For years, the plant has been used recreationally and medicinally for these effects, but its use has been implicated in and associated with intoxications and deaths. In this case report we describe two cases whereby decedents presented with single substance fatal intoxications by mitragynine in the absence of other postmortem toxicological findings. The cases entail young male decedents in outdoor settings (e.g. driving a vehicle and bicycle). Postmortem blood concentrations were 2,325 ng/mL and 3,809 ng/mL. The medical examiner (ME) certified cause of death (COD) as acute mitragynine intoxication in both cases. The toxicology results presented become useful when considering mitragynine to be the offending agent in lethal single drug intoxications; further, the information included is pertinent to medical examiners, forensic pathologists, forensic toxicologists, and emergency department personnel in evaluating possible poisoning and lethality by mitragynine.

DARK Classics in Chemical Neuroscience: Loperamide

Loperamide, a popular and inexpensive over-the-counter antidiarrheal medicine, is a potent μ-opioid receptor agonist approved by the U.S. Food and Drug Administration (FDA). It has been on the market since 1976 and is relatively safe with no central nervous system-related side effects when used for a short period of time at the recommended therapeutic dose (2-8 mg/day). In recent years, loperamide has become notoriously known as the "poor man's methadone" for people with substance dependence due to the increase in loperamide overdoses from self-administered medication to treat opioid withdrawal symptoms. As a result, in 2018, the FDA decided to limit the available packaged dose of loperamide to stop prominent abuse. This review provides the synthesis and chemical properties of loperamide as well as the pharmacology and adverse effects of its use and the social effects of such abuse.

A Case Report of Torsade de Pointes and Brugada Pattern Associated with Loperamide Misuse and Supratherapeutic Loperamide Concentrations

BACKGROUND

Loperamide, commonly sold under the brand name Imodium® (Johnson & Johnson, Fort Washington, PA), is a widely available, over-the-counter antidiarrheal medication that possesses µ-opioid agonist properties and can have catastrophic cardiac events when misused or abused. Since the start of the opioid epidemic in the United States, there has been an increasing number of case reports and deaths linking loperamide abuse with cardiac events such as torsades de pointes (TdP) and Brugada syndrome.

CASE REPORT

This case report presents a 22-year-old man who presented in cardiac arrest from polymorphic ventricular tachycardia consistent with TdP and a Type 1 Brugada pattern after intentional loperamide abuse. We discuss this patient's management and the proposed pathophysiology of these two cardiotoxicities, of which, to our knowledge, no previously published case report has displayed both in the same patient after a supratherapeutic loperamide ingestion. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: As the prevalence of opioid dependency and misuse has increased, so, too, has the misuse of un-scheduled medications such as loperamide to achieve central nervous system opioid effects. It is important for the emergency physician to know about and understand loperamide-associated cardiotoxicities such as prolongation of the QRS, unmasking of Brugada patterns, QT prolongation, or ventricular dysrhythmias such as TdP to be able to recognize and treat it.

Loperamide Abuse and Its Sequelae

INTRODUCTION

Loperamide is an opioid available over the counter and in prescription form. Loperamide functions as a μ-agonist within the enteric nervous system to slow intestinal motility. Its antidiarrheal properties and primarily peripheral activity make loperamide an important tool in the management of inflammatory bowel disease.

CASE REPORT

A 42-year-old man was found unconscious in cardiac arrest, and emergency medical personnel restored normal sinus rhythm. Family reported complaints of abdominal pain and that he "went through a lot" of loperamide. In the emergency department, the patient exhibited symptoms consistent with an opioid overdose. Mental status improved after administration of naloxone, an opioid antagonist. An electrocardiogram revealed a prolonged QTc interval, which progressed into Torsades de Pointes rhythm during admission. The patient succumbed from hypoxic brain injury, and there was evidence of acute pancreatitis at autopsy. Loperamide and desmethylloperamide (loperamide metabolite) were detected in blood samples. Cause of death was ruled loperamide toxicity.

DISCUSSION

Because of reduced central nervous system activity and associated euphoria at therapeutic doses, loperamide abuse is rarely reported. This case demonstrates that an overdose on loperamide can occur in patients seeking symptom alleviation, and may mimic the presentation of opioid overdose.

Use of Patient Health Records to Quantify Drug-Related Pro-arrhythmic Risk

There is an increasing expectation that computational approaches may supplement existing human decision-making. Frontloading of models for cardiac safety prediction is no exception to this trend, and ongoing regulatory initiatives propose use of high-throughput in vitro data combined with computational models for calculating proarrhythmic risk. Evaluation of these models requires robust assessment of the outcomes. Using FDA Adverse Event Reporting System reports and electronic healthcare claims data from the Truven-MarketScan US claims database, we quantify the incidence rate of arrhythmia in patients and how this changes depending on patient characteristics. First, we propose that such datasets are a complementary resource for determining relative drug risk and assessing the performance of cardiac safety models for regulatory use. Second, the results suggest important determinants for appropriate stratification of patients and evaluation of additional drug risk in prescribing and clinical support algorithms and for precision health.

In vitro data and computational models can assist with calculating pro-arrhythmic risk

We use patient health records and FDA Adverse Event Reporting System reports

Use of such datasets helps assess relative drug risk and cardiac safety models

We quantify how patient characteristics can affect arrhythmia incidence

Role of P-glycoprotein in the brain disposition of seletalisib: Evaluation of the potential for drug-drug interactions

Seletalisib is an orally bioavailable selective inhibitor of phosphoinositide 3-kinase delta (PI3Kδ) in clinical development for the treatment of immune-mediated inflammatory diseases. The present study investigated the role of P-gp in seletalisib disposition, especially brain distribution, and the associated risks of interactions. Seletalisib was found to be actively transported by rodent and human P-gp in vitro (transfected LLC-PK1 cells; K_m of ca. 20 µM), with minimal or no affinity for the other tested transporters. A distribution study in knockout rats (single oral dosing at 750 mg kg^-1) showed that P-gp restricts the brain disposition of seletalisib while having minimal effect on its intestinal absorption. Restricted brain penetration was also observed in cynomolgus monkeys (single oral dosing at 30 mg kg^-1) using brain microdialysis and cerebrospinal fluid sampling (K_p,uu of 0.09 and 0.24, respectively). These findings opened the question of potential pharmacokinetic interaction between seletalisib and P-gp inhibitors. In vitro, CsA inhibited the active transport of seletalisib with an IC₅₀ of 0.13 µM. In rats, co-administration of high doses of CsA (bolus iv followed by continuous infusion) increased the brain distribution of seletalisib (single oral dosing at 5 mg kg^-1). The observed data were found aligned with those predicted by in vitro-in vivo extrapolation. Based on the same extrapolation method combined with literature data, only very few P-gp inhibitors (i.e. CsA, quinine, quinidine) were predicted to increase the brain disposition of seletalisib in the clinical setting (maximal 3-fold changes).

Non-medical use of loperamide in the UK and the USA

BACKGROUND

Loperamide is a mu-opioid receptor agonist that is available as an over-the-counter anti-motility agent in the US and UK; recommended maximum doses of 12-16 mg/day. Anecdotal reports of non-medical use (NMU) have increased over the past decade with supra-therapeutic doses (70-800 mg/day) associated with cardiotoxicity. Little data exists on the prevalence of loperamide NMU.

AIM

The aim of this study was to determine the prevalence of loperamide NMU in the UK and US and to describe characteristics of non-medical loperamide users.

DESIGN

The Researched, Abuse, Diversion and Addiction Related Surveillance (RADARS® ) Survey of Nonmedical Use of Prescription Drugs (NMURx) was utilized to study NMU of loperamide among the adult population in the UK and US in 2017. The RADARS® NMURx is anonymous and self-administered online.

METHODS

A total of 40,029 completed surveys were included (10,019 from the UK and 30,010 from the US). Respondents were asked questions about medical and NMU of loperamide, frequency of and reasons for NMU, route of use problematic drug use markers, and demographics.

RESULTS

Prevalence of lifetime loperamide use (95% CI) and lifetime NMU of loperamide were: UK 28.5% (27.67-29.4), and 0.66% (0.5-0.8), respectively; US 33.7% (33.1-34.2), and 5.19% (4.9-5.5), respectively. Problematic drug use markers were elevated in those who reported NMU of loperamide in both the UK and US, however high-risk use was more prevalent in the UK than in the US.

CONCLUSION

NMU of loperamide is common. In the current international environment of opioid addiction involving both therapeutic and illicit opioids, awareness of the NMU of loperamide is important.

Characteristics of deaths associated with kratom use

BACKGROUND

Kratom (Mitragyna speciosa Korth) use has increased in Western countries, with a rising number of associated deaths. There is growing debate about the involvement of kratom in these events.

AIMS

This study details the characteristics of such fatalities and provides a 'state-of-the-art' review.

METHODS

UK cases were identified from mortality registers by searching with the terms 'kratom', 'mitragynine', etc. Databases and online media were searched using these terms and 'death', 'fatal*', 'overdose', 'poisoning', etc. to identify additional cases; details were obtained from relevant officials. Case characteristics were extracted into an Excel spreadsheet, and analysed employing descriptive statistics and thematic analysis.

RESULTS

Typical case characteristics (n = 156): male (80%), mean age 32.3 years, White (100%), drug abuse history (95%); reasons for use included self-medication, recreation, relaxation, bodybuilding, and avoiding positive drug tests. Mitragynine alone was identified/implicated in 23% of cases. Poly substance use was common (87%), typically controlled/recreational drugs, therapeutic drugs, and alcohol. Death cause(s) included toxic effects of kratom ± other substances; underlying health issues.

CONCLUSIONS

These findings add substantially to the knowledge base on kratom-associated deaths; these need systematic, accurate recording. Kratom's safety profile remains only partially understood; toxic and fatal levels require quantification.

Non-Medical Use of Novel Synthetic Opioids: A New Challenge to Public Health

Background: In the last decade there has been a progressive increase in the use of new psychoactive substances (NPSs) that are not yet under international control. In particular, novel synthetic opioids (NSOs) have reappeared on the recreational drug market in the last few years. As a result, the use of NSOs has increased rapidly. This poses an emerging and demanding challenge to public health. Aim: To raise awareness among clinicians and other professionals about NPSs, especially NSOs, to summarize current knowledge about pharmacological properties, forms of NSO on the market, pattern of use, effects and consequences of use. Methods: An electronic search was carried out on the Medline/PubMed and Google Scholar databases to find selected search terms. Results: Some NPSs are already controlled, while others can be legally sold directly on the drug market (mainly via internet, less so by drug dealers) or be used as precursors for the synthesis of other designer drugs that mimic the psychoactive effects of controlled substances. Potential side-effects of NSOs include miosis, sedation, respiratory depression, hypothermia, inhibition of gastrointestinal propulsion, death (from opioid overdose). Conclusions: The severity of the opioid crisis has intensified with the introduction of highly potent NSOs on the drug market. As long as addicts are dying from overdose or similar causes, there is something more constructive to do than waiting for addicts to overdose on heroin at a place located near a remedy, as if to say, within reach of naloxone.

Pharmacologic Treatment of Opioid Use Disorder: a Review of Pharmacotherapy, Adjuncts, and Toxicity

Opioid use disorder continues to be a significant source of morbidity and mortality in the USA and the world. Pharmacologic treatment with methadone and buprenorphine has been shown to be effective at retaining people in treatment programs, decreasing illicit opioid use, decreasing rates of hepatitis B, and reducing all cause and overdose mortality. Unfortunately, barriers exist in accessing these lifesaving medications: users wishing to start buprenorphine therapy require a waivered provider to prescribe the medication, while some states have no methadone clinics. As such, users looking to wean themselves from opioids or treat their opioid dependence will turn to alternative agents. These agents include using prescription medications, like clonidine or gabapentin, off-label, or over the counter drugs, like loperamide, in supratherapeutic doses. This review provides information on the pharmacology and the toxic effects of pharmacologic agents that are used to treat opioid use disorder. The xenobiotics reviewed in depth include buprenorphine, clonidine, kratom, loperamide, and methadone, with additional information provided on lofexidine, akuamma seeds, kava, and gabapentin.

In further defense of nonclinical abuse liability testing of biologics

Risk assessment is not a choice. Drug Abuse Liability (DAL) is mandated under international and national drug control statutes for all drugs targeting the CNS. Once administered to humans many biologics may have long-lived or permanent physiological effects that make DAL testing arduous. We respond to premises of a recently published position on DAL testing of biologics by de Zafra et al. (2018). We propose that, at a minimum, Sponsors submitting a Biologics Licensure Application (BLA) must think "outside the box" and include differential study designs for the same three core small NME assays detailed in the current DAL guidelines (self-administration, drug discrimination, and dependence liability). Abuse liability testing for drug scheduling decisions for marketing approval are not excluded or limited from risk assessment analysis simply because the entity is a biologic. In fact, more robust study designs may be necessary to address alterations in the reinforcing and discriminative stimulus effects of common drugs of abuse, as well as the dependence liability of the biologic, itself.

Is there such a thing as a 'lope' dope? Analysis of loperamide-related European Medicines Agency (EMA) pharmacovigilance database reports

Background

Among over-the-counter (OTC) drugs, loperamide has recently emerged for its potential of misuse and cardiotoxicity issues. Hence, we aimed here at assessing the loperamide-related cases being reported to the EMA's EudraVigilance (EV) database.

Methods

All spontaneous EV reports relating to loperamide misuse/abuse/dependence/withdrawal and cardiotoxicity issues were here retrieved, performing a descriptive analysis.

Findings

During the years 2005–2017, EV collected a number of 1,983 (out of a total of 7,895; 25.11%) loperamide-related misuse/abuse/dependence/withdrawal adverse drug reaction (ADR) reports, with a progressively increasing trend since 2014. Most cases were classified as drug use disorder (37.4%) or intentional overdose (25.4%). Loperamide was used on its own in 41.9% of cases; remaining, polydrug, cases included antidepressants; benzodiazepines; and other OTCs. Some 1,085 (1,085/7,895 = 13.7%) cardiovascular ADRs were reported, being conduction abnormalities and EKG alterations the most frequently identified.

Conclusions

EV data may support the levels of concern relating to loperamide potential of abuse and associated cardiotoxicity issues.

Methadone Management of Withdrawal Associated With Loperamide-related Opioid Use Disorder

: Loperamide hydrochloride is an over-the-counter anti-diarrheal agent, acting via mu-opioid receptor agonist effects in the intestinal myenteric plexus. Although preclinical investigations suggested that abuse liability associated with loperamide use is low, there are increasing numbers of cases reported to the US Food and Drug Administration, of abuse, dependence, and withdrawal associated with loperamide use. A case of a patient with opioid use disorder, that is, in the form of protracted loperamide excess use, requiring management of withdrawal with methadone is presented. Management of withdrawal from abrupt loperamide discontinuation has not been discussed in the literature. Long-term treatment issues are also described.

Abuse of Prescription Drugs in the Context of Novel Psychoactive Substances (NPS): A Systematic Review

Recently, a range of prescription and over-the-counter drugs have been reportedly used as Novel Psychoactive Substances (NPS), due to their potential for abuse resulting from their high dosage/idiosyncratic methods of self-administration. This paper provides a systematic review of the topic, focusing on a range of medications which have emerged as being used recreationally, either on their own or in combination with NPS. Among gabapentinoids, pregabalin may present with higher addictive liability levels than gabapentin, with pregabalin being mostly identified in the context of opioid, polydrug intake. For antidepressants, their dopaminergic, stimulant-like, bupropion activities may explain their recreational value and diversion from the therapeutic intended use. In some vulnerable clients, a high dosage of venlafaxine (‘baby ecstasy’) is ingested for recreational purposes, whilst the occurrence of a clinically-relevant withdrawal syndrome may be a significant issue for all venlafaxine-treated patients. Considering second generation antipsychotics, olanzapine appears to be ingested at very large dosages as an ‘ideal trip terminator’, whilst the immediate-release quetiapine formulation may possess proper abuse liability levels. Within the image- and performance- enhancing drugs (IPEDs) group, the beta-2 agonist clenbuterol (‘size zero pill’) is reported to be self-administered for aggressive slimming purposes. Finally, high/very high dosage ingestion of the antidiarrhoeal loperamide has shown recent increasing levels of popularity due to its central recreational, anti-withdrawal, opiatergic effects. The emerging abuse of prescription drugs within the context of a rapidly modifying drug scenario represents a challenge for psychiatry, public health and drug-control policies.

Fatal Poisonings Associated with New Psychoactive Substances

This chapter describes how new psychoactive substances (NPS) have been involved in fatal intoxications from 2010 and onwards. It summarizes the circumstances, antemortem symptoms, and adverse effects that have led to death after ingestion of one or more NPS and tabulates concentrations, and postmortem findings from these intoxications.Consumption of NPS exerts health problems and unknown risks for the users. Data on toxicity of many NPS are scarce or nonexistent and long-term toxicity and risks are still largely unknown. In addition, purity and composition of products containing NPS are often inconsistent or not known, which places users at high risk as evidenced by hospital emergency admissions and deaths.The most serious threat to drug users are the synthetic opioids that with strong central nervous depressant effects have caused numerous accidental deaths spread over the entire globe. The synthetic cannabinoids seem to be the most unpredictable with no clear toxidrome and unknown or poorly understood mechanisms of toxicity, but with adverse effects pointing toward the cardiovascular system. The toxidromes commonly encountered after ingestion of cathinones and phenethylamines are of sympathomimetic and hallucinogenic character, which includes risk of developing a serotonin syndrome, excited delirium, and life-threatening cardiovascular effects. In comparison to their conventional "parent" drug, i.e., heroin, cannabis, and amphetamine, most NPS appear to exhibit more severe adverse effects. The deaths attributed to NPS have dramatically increased in the last years. In our opinion, this is because of the shift from synthetic cannabinoids and cathinones to the even more toxic and dangerously potent fentanyl analogues.

Clinical Review: Loperamide Toxicity

Loperamide is a nonprescription opioid widely used for the treatment of diarrhea. Although it is relatively safe at therapeutic doses, increasing reports describe its misuse and abuse at very high doses either for euphoric effects or to attenuate symptoms of opioid withdrawal. Life-threatening loperamide toxicity can result from the relatively new clinical syndrome of loperamide-induced cardiac toxicity. These patients are often young and may present in cardiac arrest or with unheralded, recurrent syncope in conjunction with ECG abnormalities, including marked QT-interval prolongation, QRS-interval widening, and ventricular dysrhythmias. Features of conventional opioid toxicity may also be present. The mainstays of treatment include advanced cardiac life support and supportive care, although selected patients may be candidates for overdrive pacing, intravenous lipid emulsion, or extracorporeal membrane oxygenation. In patients who survive loperamide toxicity, consideration should be given to the treatment of an underlying opioid use disorder, if present.

Insights into the Role of Opioid Receptors in the GI Tract: Experimental Evidence and Therapeutic Relevance

Opioid drugs are prescribed extensively for pain treatment but when used chronically they induce constipation that can progress to opioid-induced bowel dysfunction. Opioid drugs interact with three classes of opioid receptors: mu opioid receptors (MORs), delta opioid receptors (DOR), and kappa opioid receptors (KORs), but opioid drugs mostly target the MORs. Upon stimulation, opioid receptors couple to inhibitory Gi/Go proteins that activate or inhibit downstream effector proteins. MOR and DOR couple to inhibition of adenylate cyclase and voltage-gated Ca2+ channels and to activation of K+ channels resulting in reduced neuronal activity and neurotransmitter release. KORs couple to inhibition of Ca2+ channels and neurotransmitter release. In the gastrointestinal tract, opioid receptors are localized to enteric neurons, interstitial cells of Cajal, and immune cells. In humans, MOR, DOR, and KOR link to inhibition of acetylcholine release from enteric interneurons and motor neurons and purine/nitric oxide release from inhibitory motor neurons causing inhibition of propulsive motility patterns. MOR and DOR activation also results in inhibition of submucosal secretomotor neurons reducing active Cl- secretion and passive water movement into the colonic lumen. Together, these effects on motility and secretion account for the constipation caused by opioid receptor agonists. Tolerance develops to the analgesic effects of opioid receptor agonists but not to the constipating actions. This may be due to differences in trafficking and downstream signaling in enteric nerves in the colon compared to the small intestine and in neuronal pain pathways. Further studies of differential opioid receptor desensitization and tolerance in subsets of enteric neurons may identify new drug or other treatment strategies of opioid-induced bowel dysfunction.