Drugs of Abuse: Sympathomimetics

Promising immunomodulators for management of substance and alcohol use disorders

INTRODUCTION

The neuroimmune system has emerged as a novel target for the treatment of substance use disorders (SUDs), with immunomodulation producing encouraging therapeutic benefits in both preclinical and clinical settings.

AREAS COVERED

In this review, we describe the mechanism of action and immune response to methamphetamine, opioids, cocaine, and alcohol. We then discuss off-label use of immunomodulators as adjunctive therapeutics in the treatment of neuropsychiatric disorders, demonstrating their potential efficacy in affective and behavioral disorders. We then discuss in detail the mechanism of action and recent findings regarding the use of ibudilast, minocycline, probenecid, dexmedetomidine, pioglitazone, and cannabidiol to treat (SUDs). These immunomodulators are currently being investigated in clinical trials described herein, specifically for their potential to decrease substance use, withdrawal severity, central and peripheral inflammation, comorbid neuropsychiatric disorder symptomology, as well as their ability to improve cognitive outcomes.

EXPERT OPINION

We argue that although mixed, findings from recent preclinical and clinical studies underscore the potential benefit of immunomodulation in the treatment of the behavioral, cognitive, and inflammatory processes that underlie compulsive substance use.

A single dose of cocaine raises SV2A density in hippocampus of adolescent rats

OBJECTIVE

Cocaine is a highly addictive psychostimulant that affects synaptic activity with structural and functional adaptations of neurons. The transmembrane synaptic vesicle glycoprotein 2A (SV2A) of pre-synaptic vesicles is commonly used to measure synaptic density, as a novel approach to the detection of synaptic changes. We do not know if a single dose of cocaine suffices to affect pre-synaptic SV2A density, especially during adolescence when synapses undergo intense maturation. Here, we explored potential changes of pre-synaptic SV2A density in target brain areas associated with the cocaine-induced boost of dopaminergic neurotransmission, specifically testing if the effects would last after the return of dopamine levels to baseline.

METHODS

We administered cocaine (20 mg/kg i.p.) or saline to rats in early adolescence, tested their activity levels and removed the brains 1 hour and 7 days after injection. To evaluate immediate and lasting effects, we did autoradiography with [3H]UCB-J, a specific tracer for SV2A, in medial prefrontal cortex, striatum, nucleus accumbens, amygdala, and dorsal and ventral areas of hippocampus. We also measured the striatal binding of [3H]GBR-12935 to test cocaine's occupancy of the dopamine transporter at both times of study.

RESULTS

We found a significant increase of [3H]UCB-J binding in the dorsal and ventral sections of hippocampus 7 days after the cocaine administration compared to saline-injected rats, but no differences 1 hour after the injection. The [3H]GBR-12935 binding remained unchanged at both times.

CONCLUSION

Cocaine provoked lasting changes of hippocampal synaptic SV2A density after a single exposure during adolescence.

Methamphetamine spasm in the large caliber arteries-the severity is likely underestimated

This report describes two cases of rarely reported, severe large arterial vascular spasms seen on computed tomography images after methamphetamine abuse. Although the effects of methamphetamine on the central nervous system and smaller arteries are relatively well known, its effects on large caliber arteries are rarely discussed. We present two cases of severe large arterial multisegmented vasospasm, captured on contrast-enhanced computed tomography, several hours after methamphetamine abuse. One of the patients was discharged without apparent tissue loss or organ failure. The other developed severe heart failure, liver failure, and toe gangrene. The publication of the de-identified images has been approved by the VA Central California Health Care System's Research and Development Committee and Privacy Officer. Vascular surgeons and, perhaps, acute care physicians, who are usually aware of small arterial vasospastic conditions, should also be aware of this methamphetamine-induced large arterial finding, which can be quite dramatic in appearance on imaging.

Maternal use of methamphetamine alters cardiovascular function in the adult offspring

Methamphetamine is one of the most commonly used illicit drugs during pregnancy. Most studies investigating the impact of maternal use of methamphetamine on children have focused on neurological outcomes. In contrast, cardiovascular outcomes in these children have not been characterized. Recent studies in rodents provide evidence that prenatal exposure to methamphetamine induces changes in cardiac gene expression, changes in the heart's susceptibility to ischemic injury, and changes in vascular function that may increase the risk of developing cardiovascular disorders later in life. Importantly, these changes are sex-dependent. This review summarizes our current understanding of how methamphetamine use during pregnancy impacts the cardiovascular function of adult offspring and highlights gaps in our knowledge of the potential cardiovascular risks associated with prenatal exposure to methamphetamine.

Psychiatric and non-psychiatric drugs causing false positive amphetamines urine test in psychiatric patients: a pharmacovigilance analysis using FAERS

INTRODUCTION

Immunoassay urine drug screen (UDS) is frequently used in clinical practice for initial screening process, being generally available, fast, and inexpensive. Exposure to widely prescribed drugs might determine false positive UDS amphetamines, leading to diagnostic issues, wrong therapeutic choices, impairment of physician-patient relationship and legal implications.

AREAS COVERED

To summarize and comment on a comprehensive list of compounds responsible for UDS false positive for amphetamines, we conducted a literature review on PubMed along with a comparison with Real World Data from the Food and Drug Administration Adverse Event Reporting System (FAERS) database analysis between 2010 and 2022. Forty-four articles and 125 Individual Case Safety Reports (ICSR) involving false positive amphetamine UDS in psychiatric patients were retrieved in FAERS.

EXPERT OPINION

False positive results were described in literature for antidepressants, atomoxetine and methylphenidate, antipsychotics, but also for non-psychiatric drugs of common use, like labetalol, fenofibrate and metformin. Immunoassays method is usually responsible for false positive results and in most cases mass spectrometry (MS) do not eventually confirm the UDS positivity. Physicians should be aware of immunoassays' limitations and when turning to a confirmatory test. Any new cross-reaction should be reported to pharmacovigilance activities.

Characterization of Nonfatal Opioid, Cocaine, Methamphetamine, and Polydrug Exposure and Clinical Presentations Reported to the Toxicology Investigators Consortium Core Registry, January 2010-December 2021

INTRODUCTION

To characterize and compare opioid-only, cocaine-only, methamphetamine-only, opioid-and-cocaine exposure, and opioid-and-methamphetamine exposure and to examine clinical presentations, leading to a better understanding of overdose effects involving these drug exposures.

METHODS

We examined drug exposures in the Toxicology Investigators Consortium (ToxIC) Core Registry from January 2010 to December 2021, a case registry of patients presenting to participating healthcare sites that receive a medical toxicology consultation. Demographic and clinical presentations of opioid-only, cocaine-only, methamphetamine-only, and opioid-and-cocaine exposure, and opioid-and-methamphetamine exposure consultations were described; differences between single and polydrug exposure subgroups were calculated to determine statistical significance. Clinical presentations associated with exposures were evaluated through calculated adjusted relative risk.

RESULTS

A total of 3,883 consultations involved opioids, cocaine, methamphetamine, opioid-and-cocaine exposure, or opioid-and-methamphetamine exposure. Opioid-only (n = 2,268, 58.4%) and methamphetamine-only (n = 712, 18.3%) comprised most consultations. There were significant differences in clinical presentations between exposure subgroups. Opioid-and-cocaine exposure consultations were 8.15 times as likely to present with a sympathomimetic toxidrome than opioid-only. Conversely, opioid-and-cocaine exposure and opioid-and-methamphetamine exposure were 0.32 and 0.42 times as likely to present with a sympathomimetic toxidrome compared to cocaine-only and methamphetamine-only consultations, respectively. Opioid-and-cocaine exposure was 0.67 and opioid-and-methamphetamine exposure was 0.74 times as likely to present with respiratory depression compared to opioid-only consultations. Similarly, opioid-and-cocaine exposure was 0.71 and opioid-and-methamphetamine exposure was 0.78 times as likely to present with CNS depression compared to opioid-only consultations.

CONCLUSIONS

Used in combination, opioids and stimulants may mask typical clinical presentations of one another, misattributing incorrect drugs to overdose in both clinical treatment and public health surveillance.

HIV-Tat Exacerbates the Actions of Atazanavir, Efavirenz, and Ritonavir on Cardiac Ryanodine Receptor (RyR2)

The incidence of sudden cardiac death (SCD) in people living with HIV infection (PLWH), especially those with inadequate viral suppression, is high and the reasons for this remain incompletely characterized. The timely opening and closing of type 2 ryanodine receptor (RyR2) is critical for ensuring rhythmic cardiac contraction-relaxation cycles, and the disruption of these processes can elicit Ca²⁺ waves, ventricular arrhythmias, and SCD. Herein, we show that the HIV protein Tat (HIV-Tat: 0-52 ng/mL) and therapeutic levels of the antiretroviral drugs atazanavir (ATV: 0-25,344 ng/mL), efavirenz (EFV: 0-11,376 ng/mL), and ritonavir (RTV: 0-25,956 ng/mL) bind to and modulate the opening and closing of RyR2. Abacavir (0-14,315 ng/mL), bictegravir (0-22,469 ng/mL), Rilpivirine (0-14,360 ng/mL), and tenofovir disoproxil fumarate (0-18,321 ng/mL) did not alter [³H]ryanodine binding to RyR2. Pretreating RyR2 with low HIV-Tat (14 ng/mL) potentiated the abilities of ATV and RTV to bind to open RyR2 and enhanced their ability to bind to EFV to close RyR2. In silico molecular docking using a Schrodinger Prime protein-protein docking algorithm identified three thermodynamically favored interacting sites for HIV-Tat on RyR2. The most favored site resides between amino acids (AA) 1702-1963; the second favored site resides between AA 467-1465, and the third site resides between AA 201-1816. Collectively, these new data show that HIV-Tat, ATV, EFV, and RTV can bind to and modulate the activity of RyR2 and that HIV-Tat can exacerbate the actions of ATV, EFV, and RTV on RyR2. Whether the modulation of RyR2 by these agents increases the risk of arrhythmias and SCD remains to be explored.

Effects of 3,4-Methylenedioxymethamphetamine on Conditioned Fear Extinction and Retention in a Crossover Study in Healthy Subjects

Background: 3,4-Methylenedioxymethamphetamine (MDMA) has shown initial promise as an adjunct in psychotherapy to treat posttraumatic stress disorder (PTSD). Its efficacy and safety have been demonstrated across phase I-III studies. However, the mechanism underlying the potential utility of MDMA to treat PTSD in humans has not yet been thoroughly investigated. Preliminary evidence suggests that MDMA may facilitate fear extinction recall, which may be through the release of oxytocin. To test this hypothesis, we examined the efficacy of acute MDMA treatment to enhance fear extinction learning and recall. Methods: We used a two-period, double-blind, randomized, placebo-controlled crossover design in 30 healthy male subjects who received a placebo and a single dose of MDMA (125 mg). Fear extinction was tested using two separate Pavlovian fear conditioning paradigms, one using skin conductance response (SCR), and the other fear-potentiated startle (FPS) to conditioned cues. MDMA treatment occurred after fear conditioning and 2 h before extinction learning. Extinction recall was tested 23 h after MDMA intake. Additional outcome measures included subjective effects, emotion recognition tasks, plasma levels of oxytocin, and pharmacokinetics. Results: Fear conditioning and extinction learning were successful in both fear extinction paradigms (generalized eta-squared [ges] for SCR: 0.08; FPS: 0.07). Compared to placebo treatment, MDMA treatment significantly reduced SCRs to the reinforced conditioned stimulus (CS+) during extinction learning (ges = 0.03) and recall (ges = 0.06). Intensity of the subjective effects of MDMA (good effect, trust, and openness) during extinction learning negatively correlated with the discrimination between CS+ and the safety stimulus (CS-) during recall. MDMA did not influence FPS to conditioned cues. Oxytocin concentration was increased fourfold on average by MDMA during acute effects but was not associated with fear extinction outcomes. Conclusions: MDMA treatment facilitated rapid fear extinction and retention of extinction as measured by SCR to fear cues, in line with animal studies of MDMA facilitation of extinction. However, this effect may be limited to certain forms of learned fear responses, as it was not observed in the extinction model using startle reactivity as the outcome. This study provides further evidence for the facilitation of extinction with MDMA treatment and suggests this may be a component of its efficacy when paired with psychotherapy. Clinical Trial registration: clinicaltrials.gov identifier: NCT03527316.

Clinical toxicology of exposures to chemicals from clandestine drug laboratories: a literature review

INTRODUCTION

The synthesis of clandestine drugs is a widespread worldwide phenomenon, with clandestine drug laboratories occurring both in rural and urban areas. There is considerable unfamiliarity among medical professionals about the health risks that are associated with chemicals used in clandestine drug laboratories.

OBJECTIVE

To evaluate the adverse health effects resulting from exposure to chemicals involved in the production of clandestine drugs.

METHODS

The US National Library of Medicine PubMed database and the Excerpta Medica database (EMBASE) were searched from their date of inception to October 26, 2021 using combinations of relevant search terms. This yielded 1,558 unique articles, which were subjected to two eligibility criteria: (i) exposure to clandestine drug laboratory chemicals resulting in adverse health effects; (ii) subjects were human. A total of 22 unique articles were retrieved, consisting of 10 reviews, eight case reports/series and four retrospective studies. Further searches among the references cited in these publications yielded another seven case reports/series and six retrospective studies.

RESULTS

Inhalation: Surveillance studies reported respiratory symptoms (including cough, throat irritation, nasal irritation, and dyspnea) in 59% (n = 1,657 of 2,803) of those exposed. The case reports/series described respiratory symptoms in 43% of the cases (n = 36 of 84). Lung edema was reported occasionally (n = 2). Eye exposure: Surveillance studies reported eye irritation and burns in 23% (n = 647 of 2,803) of those exposed. The case reports/series described ocular adverse events in 36% of the cases (n = 30 of 84). More severe ocular effects, such as corneal damage and conjunctival necrosis, were reported after direct eye contact with caustic fluids. Skin exposure: Surveillance studies reported dermal effects, ranging from skin irritation to severe burns, in 6% of those exposed (n = 174 of 2,803). The case reports/series described dermal effects in 30% of the cases (n = 25 of 84). Ingestion: Gastrointestinal burns were observed after ingestion of caustic substances in 5% of the patients reported in the case reports/series (n = 4 of 84). Systemic effects: Surveillance studies reported headache and dizziness in 31% (n = 882 of 2,803) and 7% (n = 187 of 2,803) of those exposed, respectively. The case reports/series described sympathomimetic effects, including mydriasis, hypertension, tachycardia, in 4% of the cases (n = 3 of 84). Fatalities: Surveillance studies reported death in 1% of those exposed (n = 29 of 2803). Ten percent of the people reported in the cases report/series died (n = 8 of 84). Death was reported after inhalation of phosphine (n = 5), hydrogen sulfide (n = 1), methanol (n = 1), and after ingestion of sulfuric acid (n = 1).

CONCLUSIONS

Exposure to chemicals involved in the production of clandestine drugs mostly resulted in mild to moderate respiratory, ocular or dermal effects, usually caused by caustic chemicals or solvents. Systemic effects were generally mild, but severe symptoms and eight deaths were reported after exposure to phosphine, hydrogen sulfide, methanol and sulfuric acid.

Many Drugs of Abuse May Be Acutely Transformed to Dopamine, Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.