The unique histology of methamphetamine cardiomyopathy: A case report

Cardiovascular magnetic resonance imaging characteristics in patients with methamphetamine-associated cardiomyopathy

BACKGROUND

Methamphetamine-associated cardiomyopathy (MA-CMP) is an increasingly recognised aetiology of cardiomyopathy. Cardiovascular magnetic resonance (CMR) is a specialised cardiac imaging modality commonly used in assessment of cardiomyopathy. We aimed to identify specific CMR features associated with MA-CMP.

METHODS

A retrospective cohort study of CMR scans was performed in a single centre between January 2015 and December 2020. Thirty patients with MA-CMP who had undergone CMR were identified. MA-CMP was defined as those with a history of significant methamphetamine use hospitalised with acute decompensated heart failure (other causes of cardiomyopathy excluded). A retrospective analysis of index admission CMRs was performed. All studies were performed on a 1.5 T CMR scanner.

RESULTS

The mean age of MA-CMP patients was 43.7 ± 7.5 years, and 86.7% were male. The mean left ventricular (LV) volume obtained in this cohort was consistent with severe LV dilatation (LV end-diastolic volume (334 ± 99 ml); LV end-systolic volume: 269 ± 98 ml), whilst the right ventricular (RV) volume indicated moderate-to-severe dilatation (RV end-diastolic volume: 272 ± 91 ml; RV end-systolic volume: 173 ± 82 ml). Mean LV ejection fraction (20.9 ± 9.2%) indicated severe LV dysfunction, with moderate-to-severe RV dysfunction also detected (RV ejection fraction: 29.4 ± 13.4%). 22 patients (73.3%) had myocardial late gadolinium enhancement (LGE), of which 59.1% were located in the mid-wall, with all of these involving the interventricular septum. 22.7% displayed localised regions of sub-endocardial LGE in a variety of locations, and 18.2% had transmural regions of LGE that were located in the inferior and inferolateral segments. 6 patients (20%) had intracardiac thrombus (4 LV, 2 both LV and RV).

CONCLUSION

MA-CMP was associated with severe biventricular dilatation and dysfunction, with a high prevalence of intraventricular thrombus. This cohort study highlights that MA-CMP patients have a high prevalence of CMR findings.

Mitochondrial dysfunction and autophagy activation are associated with cardiomyopathy developed by extended methamphetamine self-administration in rats

The recent rise in illicit use of methamphetamine (METH), a highly addictive psychostimulant, is a huge health care burden due to its central and peripheral toxic effects. Mounting clinical studies have noted that METH use in humans is associated with the development of cardiomyopathy; however, preclinical studies and animal models to dissect detailed molecular mechanisms of METH-associated cardiomyopathy development are scarce. The present study utilized a unique very long-access binge and crash procedure of METH self-administration to characterize the sequelae of pathological alterations that occur with METH-associated cardiomyopathy. Rats were allowed to intravenously self-administer METH for 96 h continuous weekly sessions over 8 weeks. Cardiac function, histochemistry, ultrastructure, and biochemical experiments were performed 24 h after the cessation of drug administration. Voluntary METH self-administration induced pathological cardiac remodeling as indicated by cardiomyocyte hypertrophy, myocyte disarray, interstitial and perivascular fibrosis accompanied by compromised cardiac systolic function. Ultrastructural examination and native gel electrophoresis revealed altered mitochondrial morphology and reduced mitochondrial oxidative phosphorylation (OXPHOS) supercomplexes (SCs) stability and assembly in METH exposed hearts. Redox-sensitive assays revealed significantly attenuated mitochondrial respiratory complex activities with a compensatory increase in pyruvate dehydrogenase (PDH) activity reminiscent of metabolic remodeling. Increased autophagy flux and increased mitochondrial antioxidant protein level was observed in METH exposed heart. Treatment with mitoTEMPO reduced the autophagy level indicating the involvement of mitochondrial dysfunction in the adaptive activation of autophagy in METH exposed hearts. Altogether, we have reported a novel METH-associated cardiomyopathy model using voluntary drug seeking behavior. Our studies indicated that METH self-administration profoundly affects mitochondrial ultrastructure, OXPHOS SCs assembly and redox activity accompanied by increased PDH activity that may underlie observed cardiac dysfunction.

Case Report Highlighting Cardiovascular Effects of Concomitant Use of Methamphetamine and Marijuana

We present the case of a 51-year-old male admitted for cardiovascular complications in the face of concomitant chronic methamphetamine and cannabis use. Upon further assessment, the patient exhibited cardiotoxicity, including acute to chronic congestive heart failure (CHF) exacerbation, hypercoagulable state, and electrolyte abnormalities. Cardiotoxicity secondary to chronic methamphetamine use has been established. However, marijuana's cardiovascular effects have not been well established. Even less information exists about the simultaneous use of methamphetamine and cannabis. With increasing interest in the use of marijuana for medical purposes, it is imperative to study any corresponding toxicity and adverse effect profile. The worldwide pattern of drug co-administration also brings the importance of this topic to light. This case report serves to provide insight into this information gap.

Methamphetamine-Associated Cardiomyopathy: Addressing the Clinical Challenges

The growth in methamphetamine usage worldwide continues to present increasing societal and health care challenges. With the escalation of its usage in a variety of social demographics, the entity of methamphetamine-associated cardiomyopathy (MA-CMP) has emerged. This entity is increasingly responsible for an important proportion of heart failure burden in both admissions to hospital and in those individuals requiring chronic heart failure care. MA-CMP poses some unique challenges including its recognition, particularly in younger patients presenting with new-onset heart failure, its severity at presentation and complications as well as management options. The challenging nature of methamphetamine addiction and the necessity to achieve abstinence is a fundamental aspect of management of this condition. As methamphetamine use continues at high levels in Australia, the burden of MA-CMP will inevitably increase and, therefore, all clinicians responsible for heart failure management require an awareness of this disease entity and the specific clinical challenges of its care.

A Comprehensive Approach to Managing Methamphetamine-Associated Cardiomyopathy

Methamphetamines are illicit drugs of the amphetamine-type stimulant class that have been increasing in popularity, availability, and purity in recent decades. As a result, rates of methamphetamine-associated cardiomyopathy (MAC) are rising globally. MAC is associated with high rates of sudden cardiac arrest, late presentation, and poor outcomes. This review discusses the medical management of MAC, including anticipated challenges specific to methamphetamine users. Not only are patients with MAC more likely to present at a younger age and with multisystem disease than patients with cardiomyopathy of other etiologies, but there may also be significant behavioral, psychosocial, financial, and system-based challenges to providing the best medical care. An individualized treatment plan that emphasizes methamphetamine abstinence as the foundation of therapy, as well as introducing optimal heart failure therapy and providing multidisciplinary support is likely to result in optimal outcomes. Given the potential reversibility of MAC, institution of guideline-directed heart failure therapy and patient support for adherence to therapy and abstinence from methamphetamines should be energetically pursued.

Methamphetamine induces cardiomyopathy by Sigmar1 inhibition-dependent impairment of mitochondrial dynamics and function

Methamphetamine-associated cardiomyopathy is the leading cause of death linked with illicit drug use. Here we show that Sigmar1 is a therapeutic target for methamphetamine-associated cardiomyopathy and defined the molecular mechanisms using autopsy samples of human hearts, and a mouse model of "binge and crash" methamphetamine administration. Sigmar1 expression is significantly decreased in the hearts of human methamphetamine users and those of "binge and crash" methamphetamine-treated mice. The hearts of methamphetamine users also show signs of cardiomyopathy, including cellular injury, fibrosis, and enlargement of the heart. In addition, mice expose to "binge and crash" methamphetamine develop cardiac hypertrophy, fibrotic remodeling, and mitochondrial dysfunction leading to contractile dysfunction. Methamphetamine treatment inhibits Sigmar1, resulting in inactivation of the cAMP response element-binding protein (CREB), decreased expression of mitochondrial fission 1 protein (FIS1), and ultimately alteration of mitochondrial dynamics and function. Therefore, Sigmar1 is a viable therapeutic agent for protection against methamphetamine-associated cardiomyopathy.

Clinical Characteristics and Management of Methamphetamine-Associated Cardiomyopathy: State-of-the-Art Review

Methamphetamine‐associated cardiomyopathy (MACM) is an increasingly recognized disease entity in the context of a rapidly spreading methamphetamine epidemic. MACM may afflict individuals with a wide range of ages and socioeconomic backgrounds. Presentations can vary greatly and may involve several complications unique to the disease. Given the public health significance of this disease, there is a relative dearth of consensus material to guide clinicians in understanding, diagnosing, and managing MACM. This review therefore aims to: (1) describe pathologic mechanisms of methamphetamine as they pertain to the development, progression, and prognosis of MACM, and the potential to recover cardiac function; (2) summarize existing data from epidemiologic studies and case series in an effort to improve recognition and diagnosis of the disease; (3) guide short‐ and long‐term management of MACM with special attention to expected or potential sequelae of the disease; and (4) highlight pivotal unanswered questions in need of urgent investigation from a public health perspective.

Methamphetamine-related cardiovascular diseases

Aims

Abuse of crystal methamphetamine (MA) poses a growing problem for health services worldwide. This review summarizes the current literature on the effects of MA on the cardiovascular system.

Methods and results

This article is a presentation of a case report and review of the current literature. In Europe, especially the eastern countries and the eastern states of Germany are affected. MA increases the concentration of catecholamines in the synaptic gap leading to euphoria, alertness, and hunger suppression as well as psychiatric and gastrointestinal complications. MA consumption is associated with hypertension, acute and chronic myocardial toxicity, stroke, coronary artery disease, and sudden cardiac death. Although many aspects of the underlying pathophysiology remain unknown, catecholamine‐mediated pathologies appear to play an important role. The duration of MA consumption is the most important determinant for the prognosis.

Conclusions

Awareness is needed as cardiac complications are important causes of morbidity and mortality in patients with MA consumption. Drug abstinence is the mainstay of therapy, cardiac and other complications should be treated according to the respective guidelines. Incompliance to therapy and frequent relapses are the main challenges for successful treatment. Further research is required to improve the understanding of this rapidly increasing cardiomyopathy.

Characteristics and Outcomes of Methamphetamine Abuse Among Veterans With Heart Failure

Methamphetamine is one of the most commonly abused illicit substances worldwide. Chronic methamphetamine abuse (MA) is associated with the development of a dilated cardiomyopathy. MA in patients with heart failure (MethHF) is increasingly reported yet poorly characterized. This was a retrospective cohort study of veterans treated at the VA Medical Center in San Diego between 2005 and 2015 with a diagnosis of HF and a history of MA. The incidence of MA each year was calculated, and clinical characteristics and outcomes of veterans with HF with and without MA were compared. Among 9,491 veterans with HF, 429 were identified as having a history of MA. Between 2006 and 2015, the incidence of MA in veterans with HF doubled from 3.44% to 6.70%. Of the 429 identified, 106 veterans had a hospitalization for HF and they were compared with veterans with HF without evidence of MA (HF). Compared with veterans with HF, veterans with MethHF were significantly younger (60.7 ± 7.3 vs 71.6 ± 11.6 years, p <0.001), with more frequent co-morbid post-traumatic stress disorder (16.8% vs 4.4%, p = 0.006), depression (28.7% vs 11.0%, p = 0.002), homelessness (27.9% vs 8.9%, p = 0.001), and unemployment (55.8% vs 30.0%, p <0.001). Despite their younger age, veterans with MethHF had high rates of HF readmission or emergency room visit (49% vs 38% in MethHF vs HF, p = 0.34) and mortality at 6 months (27% vs 38% in MethHF vs HF, p = 0.10) compared with HF. In conclusion, MA in veterans with HF is on the rise. Certain demographic and clinical characteristics of veterans with MethHF may contribute to their poor outcomes.

Fatal intoxication of a regular drug user following N-ethyl-hexedrone and ADB-FUBINACA consumption

In Hungary, N-ethyl-hexedrone (NEH) was the most frequently seized stimulant designer drug in 2017, while among synthetic cannabinoids ADB-FUBINACA and AB-FUBINACA were the most popular. Symptoms of intoxication by these substances are well known but less is known about the pathology of overdose-related death. NEH-induced fatal intoxication has not been described in the literature and knowledge surrounding the particular circumstances of death could be useful better public education of risk and more adequate treatment of overdose patients. In this report, we characterize the case of a 23-year-old male regular drug user who died a few hours after NEH and ADB-FUBINACA consumption. His medical history showed arrhythmia in childhood, and some seizures. Autopsy found he had a BMI of 42.9, a hypertrophic and dilated heart, severe atherosclerosis of the valves, coronaries and the arteries, and edema of the internal organs. Histology confirmed those findings. Postmortem blood levels of NEH were 285 ng/ml, along with 0.08 ng/ml ADB-FUBINACA and five ADB-FUBINACA metabolites. Based on the blood concentrations measured in suspected drug users (≤83.9 ng/ml) we hypothesize that NEH intoxication was the cause of death in this case, with heart disease being a co-factor and that the synthetic cannabinoid effect might have been accompaniment. This case also offered the opportunity to identify the metabolites of ADB-FUBINACA in the blood. We identified metabolites in the post-mortem blood by comparing them to human liver microsomal enzyme metabolites in vitro. Three major and two minor metabolites were found in the blood, of which two could only be derived from ADB-FUBINACA, as opposed to other cannabinoids. The case highlights the importance of the complex analysis of drug related deaths by medico-legal autopsy, histopathology and toxicology.

Hypertensive heart disease associated with methamphetamine abuse

In Japan, methamphetamine accounts for the majority of illicit drug use and dependence is becoming a critical issue. Methamphetamine abuse induces cardiovascular complications, such as cardiomyopathy and heart failure. However, methamphetamine-associated cardiovascular complications are not common in Japan. We report the case of a young patient with hypertensive heart disease associated with habitual methamphetamine abuse. A 37-year-old man was admitted with congestive heart failure. He was a habitual methamphetamine abuser and developed chronic hypertension after he started methamphetamine abuse. His echocardiogram demonstrated left ventricular concentric hypertrophy with diffuse hypokinesis. An endomyocardial biopsy revealed histological evidence of a hypertensive heart. This case shows that habitual methamphetamine use may cause hypertensive heart disease because of chronic hypertension. <Learning objective: Methamphetamine-associated cardiomyopathy and congestive heart failure are uncommon in Japan. However, habitual methamphetamine abuse can be a potential cause of hypertensive heart disease due to chronic hypertension and congestive heart failure associated with hypertrophy.>.

Rates, characteristics and circumstances of methamphetamine-related death in Australia: a national 7-year study

AIMS

To (1) assess trends in the number and mortality rates of methamphetamine-related death in Australia, 2009-15; (2) assess the characteristics and the cause, manner and circumstances of death; and (3) assess the blood methamphetamine concentrations and the presence of other drugs in methamphetamine-related death.

DESIGN

Analysis of cases of methamphetamine-related death retrieved from the National Coronial Information System (NCIS).

SETTING

Australia.

CASES

All cases in which methamphetamine was coded in the NCIS database as a mechanism contributing to death (n = 1649).

MEASUREMENTS

Information was collected on cause and manner of death, demographics, location, circumstances of death and toxicology.

FINDINGS

The mean age of cases was 36.9 years, and 78.4% were male. The crude mortality rate was 1.03 per 100 000. The rate increased significantly over time (P < 0.001), and at 2015 the mortality rate was 1.8 [confidence interval (CI) = 1.2-2.4] times that of 2009. Deaths were due to accidental drug toxicity (43.2%), natural disease (22.3%), suicide (18.2%), other accident (14.9%) and homicide (1.5%). In 40.8% of cases, death occurred outside the major capital cities. The median blood methamphetamine concentration was 0.17 mg/l, and cases in which only methamphetamine was detected had higher concentrations than other cases (0.30 versus 0.15 mg/l, P < 0.001). The median blood methamphetamine concentration varied within a narrow range (0.15-0.20 mg/l) across manner of death. In the majority (82.8%) of cases, substances other than methamphetamine were detected, most frequently opioids (43.1%) and hypnosedatives (38.0%).

CONCLUSIONS

Methamphetamine death rates doubled in Australia from 2009 to 2015. While toxicity was the most frequent cause, natural disease, suicide and accident comprised more than half of deaths.

Exposure to Amphetamines Leads to Development of Amphetamine Type Stimulants Associated Cardiomyopathy (ATSAC)

With rapidly rising prevalence of exposure to Amphetamine Type Stimulants (ATS), novel insights into cardiotoxic effects of this substance are being presented in the literature and remarkably ATS Associated Cardiomyopathy (ATSAC) is emerging as a novel cardiovascular condition with its distinctive pathogenesis, risk factors, clinical features and prognosis. A comprehensive systematic review was performed to explore and analyze the current evidence on the association between ATS exposure and development of cardiomyopathy, biological mechanisms involved in pathogenesis of ATSAC, risk factors, clinical features and course of patients with ATSAC. Several animal studies, case reports, case series and case-control studies support the association between ATS exposure and ATSAC. Oxidative stress, accelerated apoptosis, increased p53 activity, cardiomyocyte necrosis, perfusion defects, fatty acid toxicity, altered gene expression, abnormal cardiac protein synthesis and function in addition to defects in intracellular calcium hemostasis present themselves as likely mechanisms of cardiotoxicity in ATSAC. Majority of patients with ATSAC were found to be male, young and presented late with severe dilated cardiomyopathy. Female ATS users predominantly develop Takotsubo type of ATSAC and in particular its atypical basal variant. Overall, cessation of ATS exposure seems to be associated with some degree of reversibility and recovery in ATSAC sufferers.

Histopathological study of cardiac lesions in methamphetamine poisoning-related deaths

BACKGROUND

Methamphetamine abuse is a worldwide health concern. Methamphetamine causes health hazards in many vital organs. It can cause damage to cardiac tissue via catecholamines release. Methamphetamine related deaths are becoming one of the most important problems in Iran. The purpose of the present study was to determine cardiac pathology in methamphetamine poisoning-related deaths.

METHODS

The study included 100 cases of methamphetamine poisoning-related deaths and 100 cases as control group. Toxicology analysis of liver, gastric content, bile, urine, blood and vitreous humor were conducted to detect drugs, poisons and alcohols using thin layer chromatography, gas chromatography/mass spectrometry, and high performance liquid chromatography. Positive toxicology analysis results except for amphetamine and methamphetamine were excluded from the study in order to omit interfering factors. The most striking features of cardiac damage were observed by light microscopy.

RESULTS

Methamphetamine and amphetamine were detected in either urine or gastric content samples. In all of the cases methamphetamine toxicity was determined to be a direct cause of death by forensic medicine practitioner. Cardiovascular pathology was noted in 68% of studied cases. The most common histopathologic features were myocardial fiber hypertrophy, mild, moderate to severe atherosclerosis and focal degeneration/necrosis.

CONCLUSION

The results of the present study indicate that cardiotoxicity is one of the major contributing factors in methamphetamine poisoning related deaths. Overall, the current study highlights the fact that cardiotoxic effects of methamphetamine can explain increasing reports of heart failure and consequently death in young abusers.

TRIAL REGISTRATION

Not applicable. Histopathological study of cardiac lesions in methamphetamine poisoning-related deaths.

Risks associated with use of stimulant medications in patients with obstructive sleep apnea and cardiomyopathy: a case-control study

OBJECTIVES

Stimulant medications are indicated in patients with obstructive sleep apnea (OSA) who experience sleepiness despite optimal control of sleep-disordered breathing. The safety of stimulant medications in patients with OSA and co-morbid cardiomyopathy is unknown. We performed a case-control study to assess cardiovascular outcomes and mortality risk associated with stimulant use in this group of patients.

METHODS

A total of 162 subjects with OSA and cardiomyopathy were identified. Subjects who used stimulant medications for ≥1 month were designated as cases. Age-and-sex-matched controls not taking these medications were randomly chosen from the same cohort. Outcomes assessed were mortality, implantable cardioverter-defibrillator (ICD) and pacemaker insertion.

RESULTS

Twenty-two cases and 44 controls were included in the analyses. Mean age was 62.6 ± 15 years, 72% were male. Median duration of medication use was 27 months (range 1-98). There were four deaths among cases versus eight among controls. Four cases had a pacemaker and six had an ICD inserted, compared to six and eight respectively in the control group. Age (p = 0.01) and positive airway pressure (PAP) compliance (p = 0.01), but not stimulant medication use (p = 1.00) were associated with mortality on univariate analysis. In multiple logistic regression analyses accounting for body mass index, apnea-hypopnea index/respiratory disturbance index, PAP compliance, ejection fraction and duration of follow up, use of stimulant medication was not associated with mortality (p = 0.50), pacemaker (p = 0.20) or ICD (p = 0.90) implantation.

CONCLUSIONS

Stimulant medications were not associated with elevated risk of mortality, pacemaker or ICD implantation in this case-control study, even after accounting for multiple confounders.

Distinct effects of methamphetamine on autophagy-lysosome and ubiquitin-proteasome systems in HL-1 cultured mouse atrial cardiomyocytes

The aim of this study is to investigate the molecular mechanism underling the cardiotoxicity of methamphetamine, a psychostimulant drug that is currently abused in the world. A mouse atrial cardiac cell line, HL-1, which retains phenotypes of cardiac cells and serves as a useful model for examining cardiac pathophysiology, was used for this purpose. During treatment with 1mM methamphetamine (MAP) for 3-48h, massive but transient cytoplasmic vacuolization (3-12h) followed by an intracellular accumulation of granules (24-48h) was observed under light microscopy. The vacuoles were surrounded by the lysosome membrane marker LAMP1, while the granules colocalized with the autophagy markers LC3 and p62 as well as ubiquitinated proteins. Western blot analysis showed that LC3 was activated during MAP administration, although p62 was not degraded but rather accumulated. Concordant with p62 accumulation, the nuclear translocation of an anti-oxidative transcription factor, Nrf2, and the subsequent induction of its target gene, HO-1, was observed, suggesting an impairment of autophagic protein degradation and the subsequent activation of the p62/Nrf2/HO-1 pathway. In addition, proteomic analysis revealed a reduction in myosin heavy chain (MHC) protein levels during MAP administration. The ubiquitination of MHC and the induction of the muscle sarcomere protein-specific E3 ubiquitin ligases MuRF1 and atrogin-1 were proved by immunoprecipitation and quantitative real-time PCR, respectively. Taken together, the vacuolization of lysosomes and the subsequent accumulation of autophagosomes indicate an impairment of autophagic protein degradation during MAP administration; on the other hand, the ubiquitination and subsequent degradation of MHC indicate the proper progression of proteasomal degradation.

Polymorphisms in CYP2D6 may predict methamphetamine related heart failure

BACKGROUND

Methamphetamine (METH) has been associated with a dilated cardiomyopathy. The first and rate-limiting step of metabolism is dependent on the polymorphic enzyme CYP2D6.

OBJECTIVES

To evaluate if polymorphisms in CYP2D6 can be associated with the development of a methamphetamine-induced cardiomyopathy.

METHODS

We performed a prospective case-control pilot study. Cases were defined by a urinary drug screen positive for amphetamine and evidence of heart failure by beta natriuretic peptide (BNP) greater than 300 pg/ml and symptoms of heart failure. Controls were defined with urinary drug screens positive for amphetamines but without evidence of heart failure defined by a BNP lesser than 300 pg/ml or symptoms of heart failure. Exclusion criteria were less than 18 years or greater than 60 years of age, urinary toxicology screen positive for additional stimulants, known coronary artery disease (CAD) defined by greater than 50% stenosis on catheterization or previous myocardial infarction, known cardiomyopathy of alternative etiology or inability to provide consent. Patients underwent gas chromatography confirmation-mass spectroscopy for methamphetamine, genotyping of CYP2D6, limited echocardiography, and participated in a modified 2007 National Survey of Drug Use and Health Stimulant Survey. Genotype results were analyzed with traditional classifications and "Activity Scores".

RESULTS

Fifty-six patients completed the study with 19 cases and 37 controls. There was no statistically significant difference in days of use in a month, age, gender, or ethnicity between cases and controls. While not statistically significant, age and days of use did trend higher in cases. CYP2D6 genotype demonstrated that the lower the activity score/poor metabolizer group had less heart failure than extensive metabolizers/higher activity score. However, it did not reach statistical significance. When adjusting for higher days of use, extensive metabolizers had the highest odds of developing a dilated cardiomyopathy. (OR: 2.33, 95% CI: 0.54-10.13). Echo findings in all cases showed reduced ejection fractions with a mean of 18.6% (range: 10-35%) and 70% had a dilated cardiomyopathy. No cardiomyopathies were seen in the controls. Mean ejection fraction was 56.75% (range: 45-70%). The odds ratio of having a dilated cardiomyopathy in extensive metabolizers was 1.62 (95% CI: 0.47-5.5).

CONCLUSION

Our study demonstrates a trend that individuals with decreased metabolic activity were less likely to develop heart failure. While not statistically significant, a signal is present that extensive metabolizers may be at increased risk for the development of a cardiomyopathy.

Toxicity of amphetamines: an update

Amphetamines represent a class of psychotropic compounds, widely abused for their stimulant, euphoric, anorectic, and, in some cases, emphathogenic, entactogenic, and hallucinogenic properties. These compounds derive from the β-phenylethylamine core structure and are kinetically and dynamically characterized by easily crossing the blood-brain barrier, to resist brain biotransformation and to release monoamine neurotransmitters from nerve endings. Although amphetamines are widely acknowledged as synthetic drugs, of which amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are well-known examples, humans have used natural amphetamines for several millenniums, through the consumption of amphetamines produced in plants, namely cathinone (khat), obtained from the plant Catha edulis and ephedrine, obtained from various plants in the genus Ephedra. More recently, a wave of new amphetamines has emerged in the market, mainly constituted of cathinone derivatives, including mephedrone, methylone, methedrone, and buthylone, among others. Although intoxications by amphetamines continue to be common causes of emergency department and hospital admissions, it is frequent to find the sophism that amphetamine derivatives, namely those appearing more recently, are relatively safe. However, human intoxications by these drugs are increasingly being reported, with similar patterns compared to those previously seen with classical amphetamines. That is not surprising, considering the similar structures and mechanisms of action among the different amphetamines, conferring similar toxicokinetic and toxicological profiles to these compounds. The aim of the present review is to give an insight into the pharmacokinetics, general mechanisms of biological and toxicological actions, and the main target organs for the toxicity of amphetamines. Although there is still scarce knowledge from novel amphetamines to draw mechanistic insights, the long-studied classical amphetamines-amphetamine itself, as well as methamphetamine and MDMA, provide plenty of data that may be useful to predict toxicological outcome to improvident abusers and are for that reason the main focus of this review.