Gabapentinoid Pharmacology in the Context of Emerging Misuse Liability.

This article will review the epidemiology and pharmacology of gabapentinoids (gabapentin and pregabalin) relevant to their emerging misuse potential and provide guidance for clinical and regulatory management. Gabapentinoids are γ-aminobutyric acid analogues that produce their therapeutic effects by inhibiting voltage-gated calcium channels and decreasing neurotransmitter release. Recently gabapentinoid prescribing and use have increased tremendously. Although traditionally thought to possess a favorable safety profile, gabapentinoid misuse has also risen significantly. Gabapentinoid misuse generally occurs in combination with other substances, most notably opioids, and may be for purposes of eliciting euphoric effects, enhancing the effects of other substances, or self-treating conditions such as withdrawal, pain, anxiety, or insomnia. Given its faster onset, increased bioavailability and potency, and nonsaturable absorption, pregabalin's pharmacokinetics theoretically enhance its misuse liability versus gabapentin. However, gabapentin can produce similar euphoric effects, and epidemiologic studies have identified higher rates of gabapentin misuse in the United States, likely because of greater availability and less regulated prescribing. Although adverse events of gabapentinoid-only ingestion are relatively benign, a growing body of evidence indicates that gabapentinoids significantly increase opioid-related morbidity and mortality when used concomitantly. In addition, significant withdrawal effects may occur on abrupt discontinuation. As a result of these trends, several US states have begun to further regulate gabapentinoid prescribing, reclassifying it as a controlled substance or mandating reporting to local prescription drug-monitoring programs. Although increased regulation of gabapentin prescribing may be warranted, harm reduction efforts and increased patient and provider education are necessary to mitigate this concerning gabapentinoid misuse trend.

Sedative-Hypnotic Agents That Impact Gamma-Aminobutyric Acid Receptors: Focus on Flunitrazepam, Gamma-Hydroxybutyric Acid, Phenibut, and Selank.

There are many nonopioid central nervous system depressant substances that share a gamma-aminobutyric acid (GABA) receptor-related mechanism of action. These sedatives-hypnotics can be indicated to treat anxiety, seizures, depression, and insomnia but are also used as substances of abuse and used to facilitate sexual assault. Barbiturates, methaqualone, and glutethimide were among the first type A GABA receptor-mediated sedative-hypnotics. Their clinical use was limited for most indications by serious adverse events and strong abuse potential but continue to be used illicitly around the world. The benzodiazepines supplanted barbiturates for most indications because they were less likely to cause severe adverse events in monotherapy. Flunitrazepam is a newer benzodiazepine that is preferentially used recreationally and to facilitate sexual assault. Flunitrazepam has greater potency and higher affinity for the type A GABA receptor than most benzodiazepines. Gamma-hydroxybutyric acid is sought illicitly for its hypnotic, euphoric and anabolic effects as well as to facilitate sexual assault. When any of these GABAergic drugs are used in high doses or with other sedative hypnotic agents, respiratory depression, coma, and death have occurred. Chronic use of these GABAergic drugs can lead to significant withdrawal syndromes. Phenibut and selank are poorly studied Russian drugs with GABAergic mechanisms that are inexplicably sold to US consumers as dietary supplements. Poison control center calls regarding phenibut have increased substantially over the past 5 years. Desired euphoriant effects account for the recreational and illicit use of many GABA-modulating agents. However, illicit use can lead to significant toxicities related to abuse, dependence, and subsequent withdrawal syndromes. Significant evaluation of developing agents with GABA properties should be conducted to determine abuse potential before public access ensues.

Relatively mild symptoms after chronic overdose with a double-dose encorafenib: a case report.

Encorafenib (Braftovi) is indicated for the treatment of adult patients with unresectable or metastatic melanoma with a BRAF V600 mutation, in combination with binimetinib (Mektovi). According to the product label of encorafenib, there are no specific treatment recommendations in case of an overdose. We report on a 63-year-old man who ingested a double dose (900 mg) of encorafenib for 16 days. He developed overall minor chronic overdose symptoms such as nausea and vomiting grade 1 and muscle pain. Based on the most occurring adverse events of encorafenib, liver values, kidney function parameters and QTc interval were measured. Kidney function parameters were normal, whereas liver values were slightly increased (grade 1) and QTc slightly prolonged. The plasma concentration 3 h after the last dose was 2110 ng/mL. We describe the course of a case with a chronic overdose during 16 days of the double dose of encorafenib as well as the followed approach, which could be taken into account when observing an encorafenib overdose. Providing information in times of Covid-19 is challenging, but remains necessary for good clinical care.

Acute teriflunomide overdose with relatively mild symptoms: A case report.

WHAT IS KNOW AND OBJECTIVE: Teriflunomide is indicated for the treatment of adult patients with relapsing-remitting multiple sclerosis. CASE SUMMARY: We present a rare intoxication with a high dose (672 mg) of teriflunomide. According to its product label, the only known treatment is the administration of colestyramine and activated carbon (charcoal). No serious adverse events occurred during the time the patient was admitted (<24 h). No long-term overdose-related symptoms or complaints were reported. WHAT IS NEW AND CONCLUSION: The fact that after the acute overdose both adverse events and laboratory parameters were acceptable, prescribing colestyramine and activated carbon, as well as monitoring of laboratory parameters such as full blood count, liver and kidney values and QTc, seems sufficient during the early stage (<24 h after intake) of teriflunomide overdose.

The conundrum of polysubstance overdose.

WHAT IS KNOWN AND OBJECTIVE: Treating an opioid overdose using an opioid receptor antagonist (such as naloxone) makes mechanistic sense and can be effective. Unfortunately, the majority of current drug overdose deaths involve polysubstance use (i.e., an opioid plus a non-opioid). COMMENT: Respiratory depression induced by opioids results from excessive opioid molecules binding to opioid receptors. This effect can be reversed by an opioid receptor antagonist. However, the respiratory depression induced by non-opioid drugs is not due to action at opioid receptors; thus, an opioid receptor antagonist is ineffective in many of these cases. For respiratory depression induced by non-opioids, receptor antagonists are either not available (e.g., for propofol overdose) or there may be attendant risks with their use (e.g., seizures with flumazenil). This gives rise to a need for more effective ways to treat polysubstance overdose. WHAT IS NEW AND CONCLUSION: A new approach to treating opioid-induced respiratory depression due to drug overdose focuses on agents that stimulate respiratory drive rather than competing for opioid receptors. Such an approach is "agnostic" to the cause of the respiratory depression, so might be a potential way to treat polysubstance overdose.

Paracetamol overdose in the newborn and infant: a life-threatening event.

PURPOSE: Paracetamol is the only drug recommended to treat fever in neonates. At recommended doses, paracetamol has not been associated with liver injury in neonates, while hepatotoxicity may occur after intake of a single high dose or multiple excessive doses. The aim of this narrative review is to critically analyze and summarize the available literature on newborns and infants exposed to supratherapeutic doses of paracetamol, with special focus on their clinical features, outcome, and management. METHODS: The PubMed, SCOPUS, and Google Scholar search engines were used to collect data, without time limitation. The following keywords were used: paracetamol/acetaminophen, overdose, hepatotoxicity, N-acetylcysteine, newborn, infant. RESULTS: The literature search identified a total of 27 case reports, a number of review articles, and few other relevant publications. Neonatal poisoning from paracetamol resulted from transplacental drug transfer after maternal overdose in some published cases, while it was the consequence of medication errors in other cases. Newborns and infants who have received a single overdose and have paracetamol concentrations below the Rumack-Matthew nomogram limits are at low risk of serious hepatic damage, while those who have recently ingested more than one supratherapeutic dose of paracetamol should be managed with caution. The treatment of choice for paracetamol poisoning is N-acetylcysteine, a specific antidote which reduces paracetamol hepatotoxic effects. N-Acetylcysteine should be given according to specific regimens through weight-based dosing tables. CONCLUSIONS: Caution should be used when paracetamol is administered to the newborn. In the event of an overdose, careful patient monitoring and personalization of post-overdose procedures are recommended.

Quetiapine and other antipsychotics combined with opioids in legal autopsy cases: A random finding or cause of fatal outcome?

Opioid poisoning is a frequent cause of death in drug addicts and occurs with opioid treatment. Quetiapine is often found in forensic autopsies and may increase the risk of fatal opioid poisoning by enhancing sedation, respiratory depression, hypotension and QT prolongation. We systematically searched for studies of acute toxicity of quetiapine or other antipsychotics combined with morphine or methadone. Case reports describing toxicity of quetiapine combined with morphine or methadone were also included. We retrieved one human study that observed pharmacokinetic interaction between quetiapine and methadone, and 16 other human studies. Fourteen investigated the combination of droperidol and morphine in treatment doses, and some indicated an additive sedative effect. Five animal studies with acepromazine in combination with morphine or methadone were located and indicated an additive effect on sedation and hypotension. Six forensic case reports in which death could have been caused solely by quetiapine, the opioid, or other drugs were found. Thus, acute toxicity of quetiapine combined with morphine or methadone has not been studied. Because of quetiapine's effects on alpha-adrenoceptors, muscarinic and histamine receptors, human ether-a-go-go-channels and methadone kinetics, we suggest further research to clarify if the indicated additive effects of opioids and droperidol or acepromazine are also true for quetiapine.

First-Line Vasopressor and Mortality Rates in ED Patients with Acute Drug Overdose.

INTRODUCTION: While emergency department (ED) visits for acute drug overdose are at an all-time high, the importance of vasopressors to treat circulatory shock in this patient population remains unclear. This study investigated the association between first-line vasopressor and mortality, for both push-dose and infusion, in this patient population. METHODS: From a prospective cohort of consecutive ED patients with drug overdose at two urban teaching centers over 5 years, we performed a secondary data analysis of patients with circulatory shock, defined as hypotension requiring either vasopressors, high-dose insulin euglycemia therapy, or both. The first-line vasopressor (push-dose and infusion) was analyzed for associations with the primary outcome (in-hospital mortality) and secondary outcomes (24-hour mortality, ICU LOS). Subgroup analysis of beta-/calcium-channel blocker overdose was performed to evaluate impact of antidotal therapies. Data analysis included multivariable regression. RESULTS: Fifty-five patients with circulatory shock were analyzed, in whom there was 20% 24-hour mortality, 42% in-hospital mortality, 730-minute mean vasopressor duration, and 53.4-hour median ICU LOS. On multivariable analysis, there was significantly decreased adjusted odds of in-hospital mortality with first-line push-dose phenylephrine (aOR 0.06, CI 0.01-0.55), and significantly increased adjusted odds of in-hospital mortality with first-line push-dose epinephrine (aOR 60.8, CI 6.1-608). Of the first-line infusions, norepinephrine had the lowest odds of in-hospital mortality (aOR 0.80, CI 0.2-3.1). CONCLUSIONS: In ED patients with undifferentiated drug overdose and circulatory shock, the first-line vasopressor is associated with in-hospital mortality. First-line push-dose phenylephrine was associated with the lowest odds of in-hospital mortality. Future randomized studies are warranted for validation.

Endotracheal Intubation in the Pharmaceutical-Poisoned Patient: a Narrative Review of the Literature.

INTRODUCTION: Endotracheal intubation (ETI) is an essential component of the supportive care provided to the critically ill patient with pharmaceutical poisoning; however, specific nuances surrounding intubation including techniques and complications in the context of pharmaceutical poisoning have not been well elucidated. DISCUSSION: A search of the available literature on ETI in pharmaceutical-poisoned patients was undertaken using Medline, ERIC, Cochrane database, and PsycINFO using the following MeSH and keyword terms: ("toxicology" OR "poisons" OR "drug overdose" OR "poisoning") AND ("intubation, intratracheal" OR "intubation, endotracheal" OR "airway management" OR "respiration, artificial"). A hand-search was also performed when the literature in the above search required additional conceptual clarification, including using the "Similar Articles" feature of PubMed, along with reviewing articles' reference lists that discussed intubation in the context of a poisoning scenario. Articles with any discussion around the ETI process in the context of a pharmaceutical poisoning were then included. Intubation may be performed in patients poisoned with pharmaceuticals in the context of both single and multiple organ dysfunction including central and peripheral nervous system, pulmonary, or cardiovascular toxicity with hemodynamic instability, or localized effects resulting in mechanical airway obstruction. Certain classes of poisonings may require modifications to the standard rapid sequence induction airway management algorithm. CONCLUSIONS: ETI is a key component of the supportive care provided to the patient poisoned by a pharmaceutical agent. Clinicians should be aware of the spectrum of toxicities that can necessitate intubation, as well as airway management nuances that are specific to various poisoning presentations.

Cardiac arrest due to accidental overdose with norepinephrine dissolved in crystalloid.

Vasoactive agents should be administered through a controlled well-marked infusor pump, ideally via a central venous catheter if given over longer periods of time. During transfer of haemodynamically unstable patients with limited staffing and resources on site, a peripheral vasopressor infusion is sometimes resorted to as a temporary measure of optimising haemodynamic parameters. We report a case of accidental norepinephrine overdose after such practice, resulting in cardiac arrest. It illustrates the importance of careful use and labelling of vasoactive agents during the transport and handover of critically ill patients. Finally, we explore human factor issues associated with transfer from the pre-hospital to the in-hospital environment when such preparations are used.

Drug-specific risk of severe QT prolongation following acute drug overdose.

Background: Severe QT prolongation (SQTP) has been identified as a strong predictor of adverse cardiovascular events in acute drug overdose, but drug-specific causes of SQTP in the setting of acute drug overdose remain unclear. We aimed to perform the most definitive study to date describing drug-specific risk of SQTP following acute drug overdose.Methods: This was a prospective multicenter cohort study at >50 hospital sites across the US using the ToxIC Registry between 2015 and 2018. Inclusion criteria were adults (≥18 years) receiving medical toxicology consultation for acute drug overdose. The primary outcome was SQTP, which was defined using the computer automated Bazett QT correction (QTc) on the ECG with the previously validated cut point of 500 milliseconds. Mean difference in QTc was also calculated for specific drugs. Drugs associated with SQTP were analyzed using multivariable logistic regression to control for known confounders of QT risk (age, sex, race, cardiac disease).Results: From 25,303 patients screened, 6473 met inclusion criteria with SQTP occurring in 825 (13%). Drugs associated with increased adjusted odds of SQTP included Class III antidysrhythmics (sotalol), sodium channel blockers (amitriptyline, diphenhydramine, doxepin, imipramine, nortriptyline), antidepressants (bupropion, citalopram, escitalopram, trazodone), antipsychotics (haloperidol, quetiapine), and the antiemetic serotonin antagonist ondansetron.Conclusions: This large US cohort describes drug-specific risk of SQTP following acute drug overdose. Healthcare providers caring for acute drug overdoses from any of these implicated drugs should pay close attention to cardiac monitoring for occurrence of SQTP.

Unintentional Infiltration of High Dose Epinephrine in an Infant: A Case Report.

Verbal orders in the operating room between the surgeon and circulating nurse are prevalent at many institutions. We present a case in which a communication breakdown involving a verbal order resulted in the patient receiving an excessively high dose of epinephrine via subcuticular infiltration. The overdose was quickly identified by an increase in T-wave amplitude on electrocardiogram (ECG). The hemodynamic changes were treated, and the patient suffered no long-term sequelae. This report emphasizes the need to have strategies in place to prevent medication errors.

A 4-Year-Old With Altered Mental Status and Bradycardia After Clonidine Overdose.

This case presentation describes the clinical management of a pediatric patient during transport after a single-drug overdose of clonidine. Clonidine overdose closely resembles opiate intoxication, and treatment is largely supportive; however, the patient in this case presentation had a declining altered mental status with evidence of airway compromise within 1 to 2 hours after ingestion, which warranted protective airway management. The patient was extubated the following day with a successful outcome.

Evidence for the emergence of an opioid-resistant respiratory rhythm following fentanyl overdose.

Breathing resumes within one to two minutes following fentanyl overdose induced apnea in spontaneously breathing rats. As this regular rhythm is produced at a time wherein fentanyl concentrations and receptor occupancy are likely to be extremely high, the mechanisms initiating and sustaining such a respiratory activity remain unclear. Forty-four un-anesthetized adult rats were studied in an open-flow plethysmograph. Regardless of the dose of fentanyl that was used, i.e. 50 µg.kg-1 (n = 8), 100 µg.kg-1 (n = 8) or 300 µg.kg-1 (n = 7), all rats developed an immediate central apnea followed by a depressed regular rhythm that was produced 118, 97 and 81 s (median) later, respectively. Only one rat did not recover. This inspiratory and regular activity consisted of a low frequency and tidal volume pattern with a significant reduction in V̇E/V̇CO2 ratio, which persisted for at least 30 min and that was not different between 100 or 300 µg.kg-1. The time at which this respiratory rhythm emerged, following the highest dose of fentanyl, was not affected by 100 % O2 or 8% CO2/15 % O2. The absolute level of ventilation was however higher in hypercapnic and moderately hypoxic conditions than in hyperoxia. When a second injection of the highest dose of fentanyl (300 µg.kg-1) was performed at 10 min, ventilation was not significantly affected and no apnea was produced in major contrast to the first injection. When a similar injection was performed 30 min after the first injection, in a separate group of rats, an apnea and breathing depression was produced in 30 % of the animals, while in the other rats, ventilation was unaffected. We conclude that the depressed regular respiratory activity emerging during and following fentanyl overdose is uniquely resistant to fentanyl.

Acute severe intoxication with cyclopropylfentanyl, a novel synthetic opioid.

BACKGROUND: Since 2016 an increase has been observed in the availability of new synthetic opioids (NSO) in Europe. Cyclopropylfentanyl is a very potent and selective µ-opioid agonist, which was reported for the first time in August 2017 in Europe. METHODS: The case was included in a prospective observational study of patients treated in emergency departments after the intake of novel psychoactive substances (NPS). Clinical features were acquired using a structured questionnaire for physicians. Serum and/or urine samples of ED patients were analyzed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) screening methods for NPS. CASE REPORT: Within 10 min after intranasal intake of fentanyl, a 25-year-old male developed nausea, profuse sweating and dyspnoe. Because soon afterwards coma and respiratory insufficiency was noticed, the patient was admitted to hospital. After administration of naloxone (0.8 mg) breathing stabilized. However, the patient displayed recurrent decreases of oxygen saturation for 12 h. The intake of cyclopropylfentanyl was analytically confirmed. CONCLUSION: The constantly growing diversity of NSO still poses a high risk for drug users and can be a challenging task for clinicians and forensic toxicologists. Clinicians treating opioid overdoses should be aware of the potentially long lasting respiratory depression induced by fentanyl analogs.