Simon L. Hill

Clinical toxicology of newer recreational drugs

Introduction. Novel synthetic ‘designer’ drugs with stimulant, ecstasy-like (entactogenic) and/or hallucinogenic properties have become increasingly popular among recreational drug users in recent years. The substances used change frequently in response to market trends and legislative controls and it is an important challenge for poisons centres and clinical toxicologists to remain updated on the pharmacological and toxicological effects of these emerging agents. Aims. To review the available information on newer synthetic stimulant, entactogenic and hallucinogenic drugs, provide a framework for classification of these drugs based on chemical structure and describe their pharmacology and clinical toxicology. Methods. A comprehensive review of the published literature was performed using PUBMED and Medline databases, together with additional non-peer reviewed information sources, including books, media reports, government publications and internet resources, including drug user web forums. Epidemiology. Novel synthetic stimulant, entactogenic or hallucinogenic designer drugs are increasingly available to users as demonstrated by user surveys, poisons centre calls, activity on internet drug forums, hospital attendance data and mortality data. Some population sub groups such as younger adults who attend dance music clubs are more likely to use these substances. The internet plays an important role in determining the awareness of and availability of these newer drugs of abuse. Classification. Most novel synthetic stimulant, entactogenic or hallucinogenic drugs of abuse can be classified according to chemical structure as piperazines (e.g. benzylpiperazine (BZP), trifluoromethylphenylpiperazine), phenethylamines (e.g. 2C or D-series of ring-substituted amfetamines, benzodifurans, cathinones, aminoindans), tryptamines (e.g. dimethyltryptamine, alpha-methyltryptamine, ethyltryptamine, 5-methoxy-alphamethyltryptamine) or piperidines and related substances (e.g. desoxypipradrol, diphenylprolinol). Alternatively classification may be based on clinical effects as either primarily stimulant, entactogenic or hallucinogenic, although most drugs have a combination of such effects. Clinical toxicology. Piperazines, phenethylamines, tryptamines and piperidines have actions at multiple central nervous system (CNS) receptor sites, with patterns of effects varying between agents. Predominantly stimulant drugs (e.g. benzylpiperazine, mephedrone, naphyrone, diphenylprolinol) inhibit monoamine (especially dopamine) reuptake and are characteristically associated with a sympathomimetic toxidrome. Entactogenic drugs (e.g. phenylpiperazines, methylone) provoke central serotonin release, while newer hallucinogens (e.g. 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DiPT), 2,5-dimethoxy-4-bromoamfetamine (DOB)) are serotonin receptor agonists. As a result, serotoninergic effects predominate in toxicity. Conclusions. There are limited reliable data to guide clinicians managing patients with toxicity due to these substances. The harms associated with emerging recreational drugs are not fully documented, although it is clear that they are not without risk. Management of users with acute toxic effects is pragmatic and primarily extrapolated from experience with longer established stimulant or hallucinogenic drugs such as amfetamines, 3,4-methylenedioxymethamfetamine (MDMA) and lysergic acid diethylamide (LSD).

A systematic review of adverse events arising from the use of synthetic cannabinoids and their associated treatment

Abstract Context: Synthetic cannabinoids (SCs) such as “Spice”, “K2”, etc. are widely available via the internet despite increasing legal restrictions. Currently, the prevalence of use is typically low in the general community (<1%) although it is higher among students and some niche groups subject to drug testing. Early evidence suggests that adverse outcomes associated with the use of SCs may be more prevalent and severe than those arising from cannabis consumption. Objectives: To identify systematically the scientific reports of adverse events associated with the consumption of SCs in the medical literature and poison centre data. Method: We searched online databases (Medline, PsycInfo, Embase, Google Scholar and Pubmed) and manually searched reference lists up to December 2014. To be eligible for inclusion, data had to be from hospital, emergency department, drug rehabilitation services or poison centre records of adverse events involving SCs and included both self-reported and/or analytically confirmed consumption. Results: From 256 reports, we identified 106 eligible studies including 37 conference abstracts on about 4000 cases involving at least 26 deaths. Major complications include cardiovascular events (myocardial infarction, ischemic stroke and emboli), acute kidney injury (AKI), generalized tonic-clonic seizures, psychiatric presentations (including first episode psychosis, paranoia, self-harm/suicide ideation) and hyperemesis. However, most presentations were not serious, typically involved young males with tachycardia (≈37–77%), agitation (≈16–41%) and nausea (≈13–94%) requiring only symptomatic care with a length of stay of less than 8 hours. Conclusions: SCs most frequently result in tachycardia, agitation and nausea. These symptoms typically resolve with symptomatic care, including intravenous fluids, benzodiazepines and anti-emetics, and may not require inpatient care. Severe adverse events (stroke, seizure, myocardial infarction, rhabdomyolysis, AKI, psychosis and hyperemesis) and associated deaths manifest less commonly. Precise estimates of their incidence are difficult to calculate due to the lack of widely available, rapid laboratory confirmation, the variety of SC compounds and the unknown number of exposed individuals. Long-term consequences of SCs use are currently unknown.

Severe clinical toxicity associated with analytically confirmed recreational use of 25I-NBOMe: case series.

Abstract Context. 4-Iodo-2,5-dimethoxy-N-(2-methoxybenzyl)phenethylamine (25I-NBOMe) is a N-methoxybenzyl-substituted phenethylamine with potent serotoninergic effects. We describe seven cases of analytically confirmed toxicity due to the recreational use of 25I-NBOMe in the United Kingdom. Case series. Seven patients, all young adult males, presented to hospitals in the northeast of England with clinical toxicity after recreational drug use in January 2013. Clinical features included tachycardia (n = 7), hypertension (4), agitation (6), aggression, visual and auditory hallucinations (6), seizures (3), hyperpyrexia (3), clonus (2), elevated white cell count (2), elevated creatine kinase (7), metabolic acidosis (3), and acute kidney injury (1). LC–MS/MS analysis identified 25I-NBOMe as the main active substance in the plasma of all seven cases. Conclusions. Severe clinical toxicity may occur following recreational use of 25I-NBOMe, with stimulant and serotoninergic features predominating. Clinicians should be alert to this substance, in view of its emergence in Europe as well as in the United States.

Methoxetamine toxicity reported to the National Poisons Information Service: clinical characteristics and patterns of enquiries (including the period of the introduction of the UK's first Temporary Class Drug Order)

Objective To report the demographic and clinical characteristics of cases of methoxetamine toxicity reported to The National Poisons Information Service (NPIS) by healthcare professionals. To assess the pattern of enquiries from health professionals to the UK NPIS related to methoxetamine, including the period of the making of the UK first Temporary Class Drug Order (TCDO). Methods All telephone enquiries to and user sessions for TOXBASE, the NPIS on-line information resource, related to methoxetamine (and synonyms ‘MXE’, ‘mket’ and ‘2-(3-methoxyphenyl)-2-(ethylamino)cyclohexanone’) were reviewed from 1 April 2010 to 1 August 2012. Data were compared for the 3 months before and after the TCDO. Results There were 47 telephone enquiries and 298 TOXBASE sessions regarding methoxetamine during the period of study. Comparing the 3 months before and after the TCDO, TOXBASE sessions for methoxetamine fell by 79% (from 151 to 32) and telephone enquiries by 80% (from 15 to 3). Clinical features reported by enquirers were consistent with case reports of analytically confirmed methoxetamine toxicity and typical toxidromes were of stimulant (36%), reduced consciousness (17%), dissociative (11%) and cerebellar (6.4%) types, but also particularly featured acute disturbances in mental heath (43%). Conclusions Structured NPIS data may reveal trends in drugs of abuse use and toxicity when interpreted within their limitations. Since April 2012, there have been fewer enquiries to NPIS from clinicians, indicating reduced presentations with suspected methoxetamine toxicity to healthcare services. It is unclear if this is related to the TCDO made on 5 April 2012.

Clinical toxicity following analytically confirmed use of the synthetic cannabinoid receptor agonist MDMB-CHMICA. A report from the Identification Of Novel psychoActive substances (IONA) study

Abstract Context: Recreational use of Synthetic Cannabinoid Receptors Agonists (SCRAs) has become increasingly common in many countries and may cause severe toxic effects. Objective: To describe the clinical features of toxicity in seven men after analytically confirmed exposure to MDMB-CHMICA, a recently described indole-based SCRA. Materials and methods: Clinical information and biological samples (blood, urine) were collected from patients with severe toxicity after suspected use of novel psychoactive substances. Samples were analyzed by data-independent liquid chromatography–tandem mass spectrometry (LC-MS/MS). Case reports: All seven cases were men who presented to hospitals in England between July and October 2015; six reported smoking “legal high” products. In all cases, MDMB-CHMICA was identified in blood samples taken on admission to hospital. Other substances were identified in four cases (methadone 1, methiopropamine 1, other SCRAs 2). Clinical features in all seven cases and in the three exposed to MDMB-CHIMICA alone included acidosis (7/7 and 3/3) which was respiratory (3/7 and 3/3), metabolic (3/7 and 0/3) or mixed (1/7, 0/3), reduced level of consciousness (6/7 and 3/3), mydriasis (5/7 and 3/3), tachycardia (5/7 and 2/3), bradycardia (2/7 and 1/3), tonic–clonic convulsions (2/7 and 1/3) and agitation (3/7 and 1/3). Recovery occurred within 24 h in all cases except one male also exposed to methiopropamine. Conclusions: Analytically confirmed exposure to MDMB-CHMICA was associated with acidosis (often of respiratory origin), reduced level of consciousness, mydriasis, heart rate disturbances and convulsions.

Epidemiology and clinical features of toxicity following recreational use of synthetic cannabinoid receptor agonists: a report from the United Kingdom National Poisons Information Service.

Abstract Context: Toxicity from the use of synthetic cannabinoid receptor agonists (SCRAs) has been encountered increasingly frequent in many countries. Objective: To characterise presentation rates, demographic profiles and reported clinical features for users of SCRAs referred by health professionals in the United Kingdom to the National Poisons Information Service (NPIS), to compare reported toxicity between commonly used branded products, and to examine the impact of legal control measures on enquiry numbers. Methods: NPIS telephone enquiry records were searched for SCRA-related terms for the 8-year period 1st January 2007 to 31st December 2014, consolidating multiple enquiries about the same case into a single record. Demographic data, reported exposure details, clinical features and poisoning severity were analysed, excluding cases where SCRA exposure was unlikely. Results: Enquiries to the NPIS were made concerning 510 individuals relating to probable SCRA use, with annual numbers increasing year on year. Most patients were male (80.8%) and <25 years old (65.1%). Common clinical features reported in the 433 (84.9%) patients reporting SCRA use without other substances included tachycardia (n = 73, 16.9%), reduced level of consciousness (n = 70, 16.2%), agitation or aggression (n = 45, 10.4%), vomiting (n = 30, 6.9%), dizziness (n = 26, 6.0%), confusion (n= 21, 4.8%), mydriasis (n = 20, 4.6%) and hallucinations (n = 20, 4.6%). The Maximum Poisoning Severity Score (PSS) indicated severe toxicity in 36 cases (8.3%). Legal control of “second generation” SCRAs did not affect the rate of growth in enquiry numbers or the proportion with severe toxicity. The three most commonly reported products were “Black Mamba” (n= 88, 20.3%), “Pandora’s Box” (n= 65, 15.0%) and “Clockwork Orange” (n= 27, 6.2%). Neurological and general features were recorded more often with “Clockwork Orange” than for “Black Mamba” and “Pandora’s Box”, but moderate or severe toxicity was significantly less common after reported use of this product. Conclusions: Enquiries about SCRA-related toxicity have become increasingly frequent in the UK in spite of legal controls and commonly involve younger males. Differences in the patterns of toxicity associated with different branded preparations may occur, although further work with larger patient numbers is needed to confirm this.

Using poisons information service data to assess the acute harms associated with novel psychoactive substances.

Novel psychoactive substances (NPS) can cause significant acute toxicity but usually little is known about their toxicity when they enter the recreational drug scene. Current data sources include online user forums, user questionnaires, case reports/series, and deaths; however, these are limited by their focus on sub-populations and generally include severe cases and specific geographical areas. Approximately 54% of countries have at least one poisons information service (in 2012 there were 274 worldwide) providing advice to healthcare professionals and/or the public on poisoning. They provide advice on recreational drug and NPS toxicity. In 2012, 2.5% of telephone enquiries to the UK National Poisons Information Service and 2.4% of enquiries to US poisons centres related to recreational drugs. Data are collected at population level and can be used to complement other data sources with clinical details on acute NPS toxicity and geographical/time patterns of toxicity. Like other acute NPS toxicity data, poisons centre data should be interpreted within their limitations, notably the absence of analytical confirmation and reliance on secondary reporting of clinical features. This manuscript demonstrates the breadth and depth of poisons information service data in the literature with a focus on mephedrone and synthetic cannabinoid-receptor agonists. In our opinion it would be possible to develop a more robust and systematic reporting system using a network of poisons information services both within and across countries that would be complimentary to other datasets on acute NPS toxicity and allow more accurate data triangulation.

Increasing frequency of severe clinical toxicity after use of 2,4-dinitrophenol in the UK: a report from the National Poisons Information Service

Objective 2,4-Dinitrophenol (DNP) increases energy consumption by uncoupling oxidative phosphorylation. Although not licensed as a medicine, it is sometimes used by ‘body sculptors’ and for weight loss as a ‘fat burning’ agent. This research was performed to characterise patterns of presentation, clinical features and outcomes of patients reported to the National Poisons Information Service (NPIS) in the UK after exposure to DNP. Methods NPIS telephone enquiry records and user sessions for TOXBASE, the NPIS online information database, related to DNP, were reviewed from 1 January 2007 to 31 December 2013. Results Of the 30 separate systemic exposures to DNP reported by telephone to NPIS during the study period (27 males, 3 females, with a median age of 23.5 years), there were 3 during 2007–2011 (inclusive), 5 during 2012 and 22 during 2013. TOXBASE user sessions also increased sharply from 6 in 2011 to 35 in 2012 and 331 in 2013. The modes of exposure reported in telephone enquiries were chronic (n=2), acute (n=12) and subacute (n=16). Commonly reported clinical features were fever (47%), tachycardia (43%), sweating (37%), nausea or vomiting (27%), skin discolouration or rash (23%), breathing difficulties (23%), abdominal pain (23%), agitation (13%) and headache (13%). There were five (17%, 95% CI 6.9% to 34%) fatalities, four involving acute overdose. Conclusions The study indicates a substantial recent increase in clinical presentations with toxicity caused by exposure to DNP in the UK with an associated high mortality. Further steps are needed to warn potential users of the severe and sometimes fatal toxicity that may occur after exposure to this compound.

Patterns of presentation and clinical toxicity after reported use of alpha methyltryptamine in the United Kingdom. A report from the UK National Poisons Information Service

Abstract Objective. To characterise the patterns of presentation, clinical effects and possible harms of acute toxicity following recreational use of alpha methyltryptamine (AMT) in the United Kingdom, as reported by health professionals to the National Poisons Information Service (NPIS) and to compare clinical effects with those reported after mephedrone use. Methods. NPIS telephone enquiries and TOXBASE® user sessions, the NPIS online information database, related to AMT were reviewed from March 2009 to September 2013. Telephone enquiry data were compared with those for mephedrone, the recreational substance most frequently reported to the NPIS, collected over the same period. Results. There were 63 telephone enquiries regarding AMT during the period of study, with no telephone enquiries in 2009 or 2010, 19 in 2011, 35 in 2012 and 9 in 2013 (up to September). Most patients were male (68%) with a median age of 20 years. The route of exposure was ingestion in 55, insufflation in 4 and unknown in 4 cases. Excluding those reporting co-exposures, clinical effects recorded more frequently in AMT (n = 55) compared with those of mephedrone (n = 488) users including acute mental health disturbances (66% vs. 32%; Odds Ratio [OR], 4.00; 95% Confidence Intervals [CI], 2.22–7.19), stimulant effects (66% vs. 40%; OR, 2.82; 95% CI 1.57–5.06) and seizures (14% vs. 2%; OR, 9.35; 95% CI 3.26–24.18). Conclusions. Although still infrequent, toxicity following reported exposure to AMT has been encountered in the United Kingdom since January 2011. Stimulant features, acute mental health disturbances and seizures are more frequently reported than in those presenting following reported use of mephedrone.

Electrocardiographic effects of methylphenidate overdose

Objectives. Stimulants used in the management of attention-deficit hyperactivity disorder have been associated with an increased risk of sudden cardiac death. One mechanism could involve drug-induced repolarization delay, reflected as prolongation of the QT interval on the electrocardiogram, which has been described in some recipients of methylphenidate in therapeutic doses. Because QT prolongation is usually dose-related, this study was performed to investigate effects of methylphenidate overdose on the QT interval. Methods. Adults with methylphenidate overdose identified retrospectively were matched for sex and heart rate with a control subject with overdose of a noncardiotoxic substance, mainly acetaminophen. Notes were reviewed for clinical details and coingestants. Admission 12-lead electrocardiograms were individually calibrated and analyzed using a manual digitizer in a blinded manner by a single investigator. Mean QRS and QT intervals were calculated and differences between groups were analyzed. Results. Twenty-three cases of methylphenidate overdose (median reported dose 120 mg, range 40–1,500 mg) were identified (10 males, 13 females, mean age 27.8 years). There were multiple coingestants. Level of consciousness and mean hemodynamic variables were within normal limits for all cases. Symptoms recorded in cases included anxiety (32%), dilated pupils (20%), abdominal pain (16%), vomiting (12%), palpitations (12%), and chest pain (8%). No arrhythmias were recorded. Mean heart rate was 92.4/min in methylphenidate cases and 93.8/min in the heart rate-matched controls. There were no significant differences between the groups in mean QRS (cases 86.1, controls 86.2, mean difference 0.1, 95% confidence interval = −5.1 to 5.0 ms) or mean QT intervals (cases 354, controls 355, mean difference −0.8, 95% confidence interval = −10.7 to 9.2 ms). Conclusions. Methylphenidate overdose is unlikely to have substantial effects on the QRS or QT intervals.