Naloxone reversal of clonidine toxicity: dose, dose, dose

Cardiac Arrest in Special Populations

Best practices in cardiac arrest depend on continuous high-quality chest compressions, appropriate ventilatory management, early defibrillation of shockable rhythms, and identification and treatment of reversible causes. Although most patients can be treated according to highly vetted treatment guidelines, some special situations in cardiac arrest arise where additional skills and preparation can improve outcomes. Situations covered in this section involve cardiac arrest in context of electrical injuries, asthma, allergic reactions, pregnancy, trauma, electrolyte imbalances, toxic exposures, hypothermia, drowning, pulmonary embolism, and left ventricular assist devices.

The Management of Xylazine Overdose With Naloxone

This article discusses a rare case of isolated xylazine overdose in a human, treated successfully with naloxone. Xylazine, typically used as a veterinary tranquilizer, acts as a potent α2 adrenergic agonist, leading to sedation, muscle relaxation, and potential respiratory depression. In this case, a female mistakenly injected herself with xylazine mistaking it for a different medication. The report discusses naloxone's role beyond opioid overdose, especially regarding substances causing central nervous system (CNS) depression via mechanisms similar to those of opioids. While naloxone is traditionally associated with opioid receptor antagonism, its successful application here suggests potential benefits against non-opioid substances such as xylazine. The report emphasizes the need for higher naloxone dosages than those used for opioid toxicity and suggests more research into its use for treating xylazine intoxication, reflecting on the growing trend of xylazine as a recreational drug adulterant and the resulting health risks.

Evaluation of the relationship of xylazine and fentanyl blood concentrations among fentanyl-associated fatalities

INTRODUCTION

Illicit fentanyl and fentanyl-analogs have produced a devastating increase in opioid fatalities in the United States. Increasingly, xylazine has been found in the illicit fentanyl supply. The role of xylazine in fentanyl intoxication remains unclear. We reviewed coroner records to evaluate trends and effects associated with xylazine in fentanyl-related fatalities.

METHODS

This is a retrospective cohort study of all deaths reported to the Franklin County Coroner's Office in Ohio from 1 January 2019 to 16 March 2023, in which fentanyl was determined causative or contributory to death. Cases identified as fentanyl-associated fatalities were separated into two groups based on whether or not xylazine was also detected.

RESULTS

There were 3,052 fentanyl-related fatalities during the study period. 4.8 percent of these decedents also tested positive for xylazine. There was no meaningful demographic difference between fentanyl-related fatalities in which xylazine was detected versus those without xylazine detected. There was a mean of 726 fentanyl-associated fatalities per year, with a peak of 846 deaths in 2020 and a decline thereafter. The percentage of fentanyl-related fatalities with xylazine detected increased in linear fashion from 2.7 percent in 2019 to 6.6 percent in 2022. The median fentanyl concentration was 17.0 µg/L (inter-quartile range: 7.9, 27.0) in cases with xylazine detected and 10.0 µg/L (inter-quartile range: 5.6, 18.0) without xylazine. The odds of a fentanyl concentration greater than 40 µg/L in cases with xylazine detected was more than twice as great (odds ratio: 2.41; 95 percent confidence interval: 1.58-3.64) than that in cases without xylazine detected.

CONCLUSIONS

Postmortem fentanyl concentrations were greater in cases with xylazine detected than those without xylazine detected. Though it is unclear why patients who were exposed to xylazine tolerated higher opioid doses prior to succumbing to death, we postulate that xylazine may act to competitively antagonize some degree of mu-opioid receptor binding by opioids.

Xylazine potentiates the lethal but not the rewarding effects of fentanyl in mice

BACKGROUND

Fentanyl is commonly laced with xylazine. People who use this combination report heightened effects, but it also increases death risk. Although no medication has been approved to counteract overdoses produced by fentanyl and xylazine, naloxone is frequently used. This paper studies the preclinical rewarding and lethal effects of fentanyl combined with xylazine and the efficacy of yohimbine or naloxone to prevent death.

METHODS

Male Swiss Webster mice were treated with (in mg/kg, i.p.) xylazine (0.3, 1, 3, or 5.6), fentanyl (0.01, 0.3, or 0.1), or 1 xylazine plus 0.01 (non-effective) or 0.1 (effective) fentanyl doses during the conditioned-place preference (CPP) test. In addition, independent groups received (in mg/kg, i.p.): xylazine (31.6, 60, 74.2, or 100), fentanyl (3.1 or 10), or both substances at two doses: 31.6 xylazine + 3.1 fentanyl, or 60 xylazine + 10 fentanyl to analyze lethal effects. We determined whether yohimbine or naloxone (each medication tested at 10 or 30mg/kg) could prevent the lethality produced by fentanyl/xylazine combinations. Female mice were also tested in key experiments.

RESULTS

Xylazine neither induced CPP nor altered fentanyl's rewarding effects. In contrast, lethality was potentiated when fentanyl was combined with xylazine. Naloxone, but not yohimbine, effectively prevented the lethality of the fentanyl/xylazine combinations.

CONCLUSIONS

At the doses tested, xylazine does not increase the rewarding effect of fentanyl on the CPP in male mice but potentiates the risk of fatal overdose in male and female mice. A high naloxone dose prevents death induced by coadministration of fentanyl and xylazine in both sexes.

Cardiac Arrest in Special Populations

Best practices in cardiac arrest depend on continuous high-quality chest compressions, appropriate ventilatory management, early defibrillation of shockable rhythms, and identification and treatment of reversible causes. Although most patients can be treated according to highly vetted treatment guidelines, some special situations in cardiac arrest arise where additional skills and preparation can improve outcomes. Situations covered in this section involve cardiac arrest in context of electrical injuries, asthma, allergic reactions, pregnancy, trauma, electrolyte imbalances, toxic exposures, hypothermia, drowning, pulmonary embolism, and left ventricular assist devices.

Reality of clonidine poisoning in children and adolescents

AIM

We aimed to describe the severity of clonidine poisonings in a paediatric population referred to a tertiary toxicology service.

METHODS

We undertook a retrospective review of all presentations of clonidine poisoning in children or adolescents reported to a tertiary toxicology service from March 2014 to February 2020. Cases were divided into young children (0-6 years), older children (7-11 years) and adolescents (12-17 years). We report clinical effects: bradycardia, hypotension and abnormal Glasgow coma score (GCS), based on standard paediatric observation charts, interventions, length of emergency department stay, proportion admitted to a medical ward or paediatric intensive care unit.

RESULTS

We identified 111 clonidine poisonings, 41 young children, 9 older children and 61 adolescents. There were more females in the adolescent group and slightly more males in the younger age groups. The median dose ingested was 13 mcg/kg (interquartile range: 7-38 mcg/kg), which varied across ages. Clonidine alone was ingested in 78 cases (70%) and co-ingestion was more common in adolescents (24/61; 39%). Thirty-seven patients (33%) were admitted and 23 (21%) were admitted to paediatric intensive care unit. Median length of emergency department stay was 16.4 h, longer for adolescents. At least one abnormal observation occurred in 101 of 111 (91%) cases: 76 of 106 (72%) bradycardia, 76 of 110 (69%) hypotension and 4 of 99 (4%) GCS < 9. Thirteen (12%) had severe bradycardia, more common in young children and 23 (21%) had severe hypotension, more common in adolescents. For 27 children (0-11 years) ingesting 5-10 mcg/kg, 3 (11%) had severe bradycardia or severe hypotension and 1 received naloxone (4%). No cases ingesting <5 mcg/kg developed moderate/severe bradycardia or hypotension. Four cases received naloxone with no significant change, two patients got atropine with a transient response. One patient was intubated to facilitate safe inter-hospital transfer.

CONCLUSION

Paediatric clonidine poisoning commonly results in bradycardia, hypotension and decreased GCS, but rarely severe or requiring major interventions. Children ingesting <5 mcg/kg do not require admission.

Opioid overdoses involving xylazine in emergency department patients: a multicenter study

INTRODUCTION

Illicit opioids, consisting largely of fentanyl, novel synthetic opioids, and adulterants, are the primary cause of drug overdose fatality in the United States. Xylazine, an alpha-2 adrenergic agonist and veterinary tranquilizer, is being increasingly detected among decedents following illicit opioid overdose. Clinical outcomes in non-fatal overdose involving xylazine are unexplored. Therefore, among emergency department patients with illicit opioid overdose, we evaluated clinical outcome differences for patients with and without xylazine exposures.

METHODS

This multicenter, prospective cohort study enrolled adult patients with opioid overdose who presented to one of nine United States emergency departments between 21 September 2020, and 17 August 2021. Patients with opioid overdose were screened and included if they tested positive for an illicit opioid (heroin, fentanyl, fentanyl analog, or novel synthetic opioid) or xylazine. Patient serum was analyzed via liquid chromatography quadrupole time-of-flight mass spectroscopy to detect current illicit opioids, novel synthetic opioids, xylazine and adulterants. Overdose severity surrogate outcomes were: (a) cardiac arrest requiring cardiopulmonary resuscitation (primary); and (b) coma within 4 h of arrival (secondary).

RESULTS

Three hundred and twenty-one patients met inclusion criteria: 90 tested positive for xylazine and 231 were negative. The primary outcome occurred in 37 patients, and the secondary outcome occurred in 111 patients. Using multivariable regression analysis, patients positive for xylazine had significantly lower adjusted odds of cardiac arrest (adjusted OR 0.30, 95% CI 0.10-0.92) and coma (adjusted OR 0.52, 95% CI 0.29-0.94).

CONCLUSIONS

In this large multicenter cohort, cardiac arrest and coma in emergency department patients with illicit opioid overdose were significantly less severe in those testing positive for xylazine.

Pediatric Takotsubo cardiomyopathy resulting from clonidine overdose

Takotsubo cardiomyopathy is a syndrome characterized by localized apical dysfunction of the left ventricle. It is rarely seen in pediatric patients, but can carry significant morbidity and mortality. While most commonly associated with psychosocial stressors or physical exertion, a growing number of cases are being attributed to medications. We describe a case of a six-month-old male diagnosed with Takotsubo cardiomyopathy in the setting of an accidental clonidine overdose. The patient presented with altered mental status and hypertension. In the course of his broad workup, cardiac dysfunction was indicated by bedside ultrasound in the Emergency Department. The classic apical dyskinesis was seen on a follow-up, cardiology-based echocardiogram. The patient responded to high-dose naloxone and only briefly required an epinephrine infusion. His symptoms resolved in a few days and serial echocardiograms showed a return to normal LV function. Rates of pediatric clonidine overdoses are increasing in the setting of changing prescribing practices. Our case illustrates some key features of the clinical presentation, as well as demonstrates a rare sequelae to this common toxic exposure. To our knowledge, this is the first reported pediatric case of Takotsubo cardiomyopathy secondary to a clonidine overdose.

Systemic toxicity from subcutaneous brimonidine injection successfully treated with naloxone: A case report

Brimonidine is a topical ophthalmic alpha-2 adrenergic agonist solution used to treat glaucoma. The toxidrome includes drowsiness, lethargy, hypotension, bradycardia, and respiratory depression when ingested in infants. We report a case of intentional subcutaneous injection of brimonidine in an elderly patient resulting in hypotension and CNS depression that responded to naloxone. A 73-year-old female with a past medical history significant for glaucoma, hypertension, and indwelling pacemaker presented to the emergency department after injecting her brimonidine tartrate ophthalmic solution subcutaneously (SQ). The patient was not taking any antihypertensive medications or opioids. Initial presentation consisted of lethargy, a paced rhythm of 60 bpm, and blood pressure of 91/24 mmHg with a MAP of 46. Due to central nervous system depression, 3 mg of intranasal naloxone was administered. The patient was treated with intravenous fluids and escalating doses of naloxone and required a continuous infusion. Mental status and vital signs subsequently improved. The patient was admitted to the ICU and naloxone was subsequently weaned over 12 h. Systemic central alpha-2 adrenergic agonist toxicity resulted from SQ brimonidine injection. Central alpha-2 adrenergic agonist overdoses present as sympatholytic effects including CNS depression, bradycardia, hypotension, and may mimic the opioid toxidrome. Brimonidine SQ injection has not previously been reported and this case has similar findings to other central alpha-2 adrenergic agonist poisonings. Naloxone has previously shown variable reversal of CNS depression in central alpha-2 overdose. In this case, high-dose naloxone was useful for reversing CNS depression and hemodynamic instability.

Xylazine poisoning: a systematic review

PURPOSE

Xylazine is an alpha-2-adrenergic agonist used for its sedative and analgesic properties in veterinary medicine. While not approved by the Food and Drug Administration for use in humans, anecdotal evidence suggests that exposures in humans is on the rise. We sought to systematically review and synthesize the evidence on xylazine exposure in humans focusing on the clinical presentation, management, and outcomes.

METHODS

We conducted a systematic review of the literature including PubMed, Embase, and Scopus from their inception to September 9, 2021. We searched abstracts from selected emergency medicine and toxicology conferences from 2011 through 2021. We included clinical reports of xylazine exposure in humans. We excluded animal studies, in vitro studies, laboratory studies, or articles in a language other than English. From each included article, we extracted subjective and objective data that focused on clinical presentation, management, and outcomes of patients exposed to xylazine.

RESULTS

We evaluated a total of 1409 records, rendering a final set of 17 articles and 2 abstracts meeting inclusion criteria. We identified a total of 98 patients amongst reports ranging from 1979 to 2020 and across nine countries. The most common types of xylazine exposures reported were unintentional exposure and intentional misuse/abuse. Common symptoms on presentation included hypotension, bradycardia, drowsiness, lethargy, while apnea with intubation and death were less frequently reported.

CONCLUSION

Human exposure to xylazine appears to be a rising concern within the prehospital and emergency medicine setting. Although a standardized treatment algorithm cannot be recommended at this time, further research is needed to improve the care of patients exposed to xylazine.

Perioperative Implications of the 2020 American Heart Association Scientific Statement on Drug-Induced Arrhythmias-A Focused Review

The recently released American Heart Association (AHA) scientific statement on drug-induced arrhythmias discussed medications commonly associated with bradycardia, supraventricular tachycardias, and ventricular arrhythmias. The foundational data for this statement were collected from general outpatient and inpatient populations. Patients undergoing surgical and minimally invasive treatments are a unique subgroup, because they may experience hemodynamic changes associated with anesthesia and their procedure, receive multiple drug combinations not given in either inpatient or outpatient settings, or experience postprocedural inflammatory syndromes. Accordingly, the generalizability of the AHA scientific statement to this perioperative population is unclear. This focused review highlights important aspects of the new AHA scientific statement and their application to the perioperative setting. The authors review medications frequently encountered and given by anesthesiologists and their risk of drug-induced arrhythmias and discuss common anesthetic and adjunctive medications and their associated risks of bradycardia, atrial fibrillation, torsades de pointes, and drug-induced Brugada syndrome. In many instances, the risk of arrhythmia reported by the AHA scientific statement in the general population appeared to be higher than found in perioperative arenas. Furthermore, the authors discuss the arrhythmia risk of additional medications commonly ordered or administered by anesthesiologists that are not included in the AHA scientific statement. As patient and procedural complexity increases and novel anesthetic combinations propagate, further research and observational studies will be required to delineate further perioperative risks for drug-induced arrhythmia.

"Road Rash" and Dizziness: A Case of Hemodynamically Significant Topical Clonidine Toxicity

Clonidine is a central alpha-2 agonist well known to produce a syndrome of bradycardia and hypotension in overdose. However, few examples of overt clinical clonidine toxicity secondary to cutaneous absorption have been reported. We report a case of unintentional systemic clonidine toxicity in an adult because of a compounded preparation of clonidine applied to a degraded skin barrier. A 35-year-old male suffered a motorcycle accident 48 hours before presentation resulting in an abrasion to his distal left leg. On the day of presentation, he self-treated the wound by repeated application of a family member's pain-relieving cream. Later he was found confused and unable to stand by a family member. The family member recognized the thick visible coat of cream as the likely cause and decontaminated the patient while calling 911. Prehospital vitals were notable for a blood pressure of 80/30 mm Hg and heart rate of 38 beats per minute. In the emergency department, the patient was resuscitated with intravenous fluids with resultant normalization of blood pressure. Upon later review, the cream was determined to have been created by a local compounding pharmacy for the use in neuropathic pain and was labeled to contain clonidine, lidocaine, ketamine, and gabapentin. Cutaneous absorption of the pain cream was greatly increased because of loss of skin integrity. Military physicians and compounding pharmacies should ensure that patients are aware of the proper application of compounded creams and the potential risk for systemic toxicity with overuse or degraded skin.

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.

Clinical Effects of Pediatric Clonidine Exposure: A Retrospective Cohort Study at a Single Tertiary Care Center

BACKGROUND

Pediatric clonidine ingestions frequently result in emergency department visits and admission for cardiac monitoring. Detailed information on the clinical course and specifically time of vital sign abnormalities of these patients is lacking.

OBJECTIVE

The objective of this study was to provide descriptive analysis of the rates and times to vital sign abnormalities, treatment, disposition, and outcomes in a single-center cohort of pediatric patients with report of clonidine poisoning.

METHODS

We performed a retrospective cohort study of patients younger than 21 years who presented to a large, urban, tertiary care center with a report of single substance clonidine exposure between January 2004 and November 2017. Patients were dichotomized into younger (≤9 years or younger) and older (10-21 years) groups based on the expected physiologic and psychologic differences between older and younger children.

RESULTS

Eighty-eight patients met our inclusion criteria. Younger patients (≤9 years or younger; n = 47) were more likely to be exposed to someone else's medication (53%) and older patients (10-21 years; n = 41) overwhelmingly (85%) were exposed to their own medication. Thirty-nine (45%) became bradycardic, 27 (32%) became bradypneic, and 38 (44%) became hypotensive. Eighty percent of patients had depressed mental status. Thirty-three (38%) patients received at least one dose of naloxone (median 0.07 mg/kg; interquartile range 0.03-0.11 mg/kg). Of those who received naloxone, 50% had a documented clinical response.

CONCLUSIONS

In this study of patients at a pediatric tertiary referral center, pediatric patients with report of clonidine exposures were likely to exhibit altered mental status and frequently develop vital sign abnormalities. Naloxone exhibited some effectiveness; given its wide safety margin, high-dose naloxone should be used in critically poisoned non-opioid-dependent patients. Because adolescents are much more likely to ingest their own clonidine medication, counseling with parents and other caregivers regarding safe medication storage is paramount.

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.

Reversal of the effects of clonidine using naloxone

An 18-year-old man underwent surgery for correction of idiopathic scoliosis. Due to the requirement for intra-operative spinal cord monitoring, propofol and remifentanil total intravenous anaesthesia was chosen as the anaesthetic technique. Clonidine was given intra-operatively as part of his analgesic regimen. No long-acting opioids were administered. There was delayed emergence after switching off total intravenous anaesthesia and he remained sedated with a bispectral index of approximately 60 for 90 min. The common causes of delayed emergence were excluded. Shortly after administering naloxone, there was an increase in bispectral index and emergence from anaesthesia. We describe the successful use of naloxone to reverse the sedation effects of clonidine.

Effects of 24 CYP2D6 variants found in Chinese population on the metabolism of clonidine in vitro

BACKGROUND AND OBJECTIVES

Clonidine has been clinically used to treat Tourette's syndrome for decades. There was research finding that clonidine possessed the best risk-benefit ratio, especially for patients associated with attention deficit hyperactivity disorder. CYP2D6 is a significant member of Cytochrome P450 enzymes. The genetic polymorphisms of CYP2D6 greatly affect the clinical effects of drugs even lead to side effects and medical malpractice. Our goal is to research the effect of CYP2D6 genetic polymorphism on the metabolism of clonidine and evaluate the functions of 22 CYP2D6 allelic variants in vitro, which were discovered in Chinese Han population recently.

METHODS

This study was carried out through a mature incubation system. The wild-type CYP2D6*1 and 24 variants (CYP2D6*2, CYP2D6*10 and 22 novel CYP2D6 variants) were expressed in insect cells, and the catalytic activity of all the variants were assessed by substrate clonidine. Metabolite 4-OH clonidine was accurately detected via ultra-performance liquid-chromatography tandem mass spectrometry to evaluate the effect of CYP2D6 genetic polymorphism on the clonidine.

RESULT

Among the 22 novel CYP2D6 variants, the intrinsic clearance (Vmax/Km) of 21 variants were significantly decreased (from 1.53% to 83.25%) compared to the wild-type. In particular, the following seven variants (CYP2D6* 2, CYP2D6* 10, CYP2D6* 93, CYP2D6* 95, E215K, V327 M and R497C) attract more attention, of which the intrinsic clearance decreased more than 70% compared to the wild-type. Because the variants with significantly reduced intrinsic clearance are more likely to cause adverse reactions than the variants with increased or little changed intrinsic clearance. In addition, the related pharmacokinetic parameters of CYP2D6*92 and CYP2D6*96 could not be acquired for the defect of CYP2D6 nucleotide.

CONCLUSION

We comprehensively evaluated the effect of 22 novel CYP2D6 variants on the metabolism of clonidine for the first time and hoped corresponding data provide a reference for metabolism of clonidine for further studies in vivo, and extend our understanding of the clinical drug toxicity or ineffectiveness by CYP2D6 genetic polymorphism.

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

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