Oxycodone overdose causes naloxone responsive coma and QT prolongation

Opioids-Induced Long QT Syndrome: A Challenge to Cardiac Health

The challenge posed by opioid overdose has become a significant concern for health systems due to the complexities associated with drug prohibition, widespread clinical use, and potential abuse. In response, healthcare professionals have primarily concentrated on mitigating the hallucinogenic and respiratory depressant consequences of opioid overdose to minimize associated risks. However, it is crucial to acknowledge that most opioids possess the capacity to prolong the QT interval, particularly in cases of overdose, thereby potentially resulting in severe ventricular arrhythmias and even sudden death if timely intervention is not implemented. Consequently, alongside addressing the typical adverse effects of opioids, it is imperative to consider their cardiotoxicity. To enhance comprehension of the correlation between opioids and arrhythmias, identify potential targets for prompt intervention, and mitigate the hazards associated with clinical utilization, an exploration of the interaction between drugs and ion channels, as well as their underlying mechanisms, becomes indispensable. This review primarily concentrates on elucidating the impact of opioid drugs on diverse ion channels, investigating recent advancements in this domain, and attaining a deeper understanding of the mechanisms underlying the prolongation of the QT interval by opioid drugs, along with potential interventions.

Tapentadol exposures and poisonings in Australia

INTRODUCTION

Tapentadol is an atypical opioid with mu-receptor affinity and noradrenaline reuptake inhibition approved for use in Australia in 2011. However, data on tapentadol poisoning are scarce.

OBJECTIVES

To investigate tapentadol poisonings and related deaths in Australia.

METHODS

We performed a retrospective review of tapentadol poisonings from New South Wales Poisons Information Centre (NSWPIC) and three toxicology units in Australia. The National Coronial Information System (NCIS) database was searched to determine the number of tapentadol-related deaths.

RESULTS

Between 2016 and 2020, 220 tapentadol calls were made to NSWPIC, with a 4.5-fold increase in tapentadol exposure calls. The median dose ingested was 575 mg (IQR: 300-1163 mg). Most overdoses included co-ingestions (75%), especially benzodiazepines (26%) and opioids (25%). From Jan 2016 to Dec 2021, 107 patients presented to the three toxicology units with tapentadol poisoning. The median dose ingested was 500 mg (IQR: 200-1400 mg). Most patients took co-ingestants (84%), including benzodiazepines (40%) and opioids (32%). Naloxone was administered in 39 patients (36%), 10 (9%) were intubated and the median length of stay was 18 h (IQR: 9-30). Thirty-five tapentadol-related deaths were recorded within NCIS between Jan 2015 and Oct 2021 with a median age of 51 years (IQR: 42-61 years).

CONCLUSION

There are increasing tapentadol poisonings and deaths reported to the NSWPIC, three toxicology units, and NCIS in Australia. Most tapentadol poisonings were taken with benzodiazepines and/or other opioids.

Effects of opioid receptor agonist and antagonist medications on electrocardiogram changes and presentation of cardiac arrhythmia: review article

BACKGROUND/PURPOSE

Mortality associated with prescription opioids has significantly increased over the past few decades and is considered a global pandemic. Prescribed opioids can cause cardiac arrhythmias, leading to fatal outcomes and unexpected death, even in the absence of structural cardiac disease. Despite the extent of cardiac toxicity and death associated with these medications, there is limited data to suggest their influences on cardiac electrophysiology and arrhythmias, with the exception of methadone. The goal of our review is to describe the possible mechanisms and to review the different ECG changes and arrhythmias that have been reported.

METHODS

A literature search was performed using Google Scholar, PubMed, Springer, Ovid, and Science Direct to identify studies that demonstrated the use of prescription opioids leading to electrocardiogram (ECG) changes and cardiac arrhythmias.

RESULTS

Many of the commonly prescribed opioid medications can uniquely effect the ECG, and can lead to the development of various cardiac arrhythmias. One of the most significant side effects of these drugs is QTc interval prolongation, especially when administered to patients with a baseline risk for QTc prolongation. A prolonged QTc interval can cause lethal torsades de pointes and ventricular fibrillation. Obtaining an ECG at baseline, following a dosage increase, or after switching an opioid medication, is appropriate in patients taking certain prescribed opioids. Opioids are often used first line for the treatment of acute and chronic pain, procedural sedation, medication opioid use disorders, and maintenance therapy.

CONCLUSIONS

To reduce the risk of cardiac arrhythmias and to improve patient outcomes, consideration of accurate patient selection, concomitant medications, electrolyte monitoring, and vigilant ECG monitoring should be considered.

Cardiovascular Complications of Opioid Use: JACC State-of-the-Art Review

Opioids are the most potent of all analgesics. Although traditionally used solely for acute self-limited conditions and palliation of severe cancer-associated pain, a movement to promote subjective pain (scale, 0 to 10) to the status of a "fifth vital sign" bolstered widespread prescribing for chronic, noncancer pain. This, coupled with rising misuse, initiated a surge in unintentional deaths, increased drug-associated acute coronary syndrome, and endocarditis. In response, the American College of Cardiology issued a call to action for cardiovascular care teams. Opioid toxicity is primarily mediated via potent μ-receptor agonism resulting in ventilatory depression. However, both overdose and opioid withdrawal can trigger major adverse cardiovascular events resulting from hemodynamic, vascular, and proarrhythmic/electrophysiological consequences. Although natural opioid analogues are devoid of repolarization effects, synthetic agents may be proarrhythmic. This perspective explores cardiovascular consequences of opioids, the contributions of off-target electrophysiologic properties to mortality, and provides practical safety recommendations.

γ-Hydroxybutyric Acid: Pharmacokinetics, Pharmacodynamics, and Toxicology

Gamma-hydroxybutyrate (GHB) is a short-chain fatty acid present endogenously in the brain and used therapeutically for the treatment of narcolepsy, as sodium oxybate, and for alcohol abuse/withdrawal. GHB is better known however as a drug of abuse and is commonly referred to as the "date-rape drug"; current use in popular culture includes recreational "chemsex," due to its properties of euphoria, loss of inhibition, amnesia, and drowsiness. Due to the steep concentration-effect curve for GHB, overdoses occur commonly and symptoms include sedation, respiratory depression, coma, and death. GHB binds to both GHB and GABAB receptors in the brain, with pharmacological/toxicological effects mainly due to GABAB agonist effects. The pharmacokinetics of GHB are complex and include nonlinear absorption, metabolism, tissue uptake, and renal elimination processes. GHB is a substrate for monocarboxylate transporters, including both sodium-dependent transporters (SMCT1, 2; SLC5A8; SLC5A12) and proton-dependent transporters (MCT1-4; SLC16A1, 7, 8, and 3), which represent significant determinants of absorption, renal reabsorption, and brain and tissue uptake. This review will provide current information of the pharmacology, therapeutic effects, and pharmacokinetics/pharmacodynamics of GHB, as well as therapeutic strategies for the treatment of overdoses. Graphical abstract.

Opioids and Cardiac Arrhythmia: A Literature Review

OBJECTIVE

One of the most important side effects of opioids is their influence on the electrical activity of the heart. This review focusses on the effects of opioids on QT interval prolongation and their arrhythmogenic liability.

METHODS

By using various keywords, papers published up to 2018 in different databases were searched and identified. The search terms were opioids names, corrected QT interval, human-ether-a-go-go gene, torsades de pointes (TdP), cardiac arrhythmias, opioid dependence and other relevant terms. It emphasized the effects of each opioid agent alone on electrocardiogram (ECG) and some interactions.

RESULTS

Available data indicate that some opioids such as methadone are high-risk even at low doses, and have potential for prolongation of the QT interval and development of TdP, a dangerous ventricular tachycardia. A number of opioids such as tramadol and oxycodone are intermediate risk drugs and may develop long QT interval and TdP in high doses. Some other opioids such as morphine and buprenorphine are low-risk drugs and do not produce QT interval prolongation and TdP at least in routine doses. Opium-consumers are at higher risk of supra-ventricular arrhythmias, sinus bradycardia, cardiac block and atrial fibrillation.

CONCLUSION

The cardiac arrhythmogenicity of various opioids is different. Methadone has a higher capability to induce long QT interval and dangerous arrhythmias in conventional doses than others. To reduce of arrhythmogenic risk, high doses of opioids must be used cautiously with periodic monitoring of ECG in high-risk consumers such as patients under opioid maintenance treatment.

Pain medication and long QT syndrome

Long QT syndrome is a cardiac repolarization disorder and is associated with an increased risk of torsades de pointes. The acquired form is most often attributable to administration of specific medications and/or electrolyte imbalance. This review provides insights into the risk for QT prolongation associated with drugs frequently used in the treatment of chronic pain. In the field of pain medicine all the major drug classes (i.e. NSAIDs, opioids, anticonvulsive and antidepressant drugs, cannabinoids, muscle relaxants) contain agents that increase the risk of QT prolongation. Other substances, not used in the treatment of pain, such as proton pump inhibitors, antiemetics, and diuretics are also associated with long QT syndrome. When the possible benefits of therapy outweigh the associated risks, slow dose titration and electrocardiography monitoring are recommended.

The Impact of Opioids on Cardiac Electrophysiology

Synthetic opioid agents have been used in modern medicine for over a century and for opioid addiction treatment for over a half-century. Liberal use of opioids in the United States has been attended by an extraordinary increase in opioid-related mortality, with over 16,000 deaths in 2012. As there have been advances in opioid agents for pain and addiction, so have there been advances in our understanding of the cardiac effects of these agents. In the last 10 years, significant data regarding electrophysiologic effects of these agents have been collected. We aim in this review to discuss the effects on cardiac electrophysiology of the various opioid agents currently in use and the evidence that these effects are contributing to the rise in opioid-related mortality.

The opioid abuse and misuse epidemic: implications for pharmacists in hospitals and health systems

PURPOSE

The current epidemic of prescription opioid abuse and misuse in the United States is discussed, with an emphasis on the pharmacist's role in ensuring safe and effective opioid use.

SUMMARY

U.S. sales of prescription opioids increased fourfold from 1999 to 2010, with an alarming rise in deaths and emergency department visits associated with the use of fentanyl, hydrocodone, oxycodone, and other opioid medications. Signs and symptoms of opioid toxicity may include altered mental status, hypoventilation, decreased bowel motility, central nervous system and respiratory depression, peripheral vasodilation, pulmonary edema, hypotension, bradycardia, and seizures. In patients receiving long-term opioid therapy for chronic pain, urine drug testing is an important tool for monitoring and assessment of therapy; knowledge of opioid metabolic pathways and assay limitations is essential for appropriate use and interpretation of screening and confirmatory tests. In recent years, there has been an increase in federal enforcement actions against pharmacies and prescription drug wholesalers involved in improper opioid distribution, as well as increased reliance on state-level prescription drug monitoring programs to track patterns of opioid use and improper sales. Pharmacies are urged to implement or promote appropriate guidelines on opioid therapy, including the use of pain management agreement plans; policies to ensure adequate oversight of opioid prescribing, dispensing, and waste disposal; and educational initiatives targeting patients as well as hospital and pharmacy staff.

CONCLUSION

Pharmacists in hospitals and health systems can play a key role in recognizing the various forms of opioid toxicity and in preventing inappropriate prescribing and diversion of opioids.

The Half RR Rule: A Poor Rule of Thumb and Not a Risk Assessment Tool for QT Interval Prolongation

OBJECTIVES

Measuring the QT interval on an electrocardiogram (ECG) is integral to risk assessment of Torsade de Pointes (TdP). This study aimed to investigate the accuracy of the 1/2 RR rule as a risk assessment tool for drug-induced TdP, comparing it to the QT nomogram, Bazett's corrected QT (QTcB), and Fridericia's corrected QT (QTcF).

METHODS

The authors calculated sensitivity and specificity of the 1/2 RR rule using a published data set of 129 cases of drug-induced TdP and 316 controls (noncardiotoxic overdoses), compared to the QT nomogram, QTcB > 500 msec and QTcF > 500 msec. To further determine the value of the 1/2 RR rule, its observed positive, and negative agreement were calculated when compared to the QT nomogram for determining an abnormal QT in eight samples of different drugs in overdose.

RESULTS

The sensitivity and specificity of the 1/2 RR rule were 88% (95% confidence interval [CI] = 80% to 93%) and 53% (95% CI = 47% to 58%), respectively, compared to the QT nomogram (sensitivity = 97%, 95% CI = 92% to 99%; specificity = 99%, 95% CI = 97% to 100%). It was also less sensitive than QTcB > 500 msec and had a lower specificity than QTcB > 500 msec and QTcF > 500 msec. In drug overdose patients, the 1/2 RR rule had poor observed agreement averaging 41%, which was mainly due to poor positive agreement, except for amisulpride where there was good agreement.

CONCLUSIONS

The 1/2 RR rule was not as sensitive as the QT nomogram or QTcB > 500 msec for drug-induced TdP. It had poor positive agreement in almost all overdose patients, resulting in over half of patients receiving unnecessary cardiac monitoring and repeat ECGs.

Tramadol overdose causes seizures and respiratory depression but serotonin toxicity appears unlikely

CONTEXT

Tramadol is a commonly used centrally acting analgesic associated with seizures and suspected to cause serotonin toxicity in overdose.

OBJECTIVE

This study sought to investigate the effects of tramadol overdose, and included evaluation for serotonin toxicity based on the Hunter Serotonin Toxicity Criteria where the seven clinical features of spontaneous clonus, inducible clonus, ocular clonus, agitation, diaphoresis, tremor and hyperreflexia are examined for in all patients taking serotonergic medications; seizures and central nervous system depression.

MATERIALS AND METHODS

This was an observational cases series based on a retrospective review of tramadol overdoses (> 400 mg) admitted to a tertiary toxicology unit from November 2000 to June 2013. Demographic details, information on ingestion (dose and co-ingestants), clinical effects, complications (seizures, serotonin toxicity and cardiovascular effects) and intensive care unit (ICU) admission were extracted from a clinical database.

RESULTS

There were 71 cases of tramadol overdose (median age: 41 years, range: 17-69 years; and median ingested dose: 1000 mg, interquartile range [IQR]: 800-2000 mg). Seizures were dose related and occurred in 8 patients, one of them co-ingested a benzodiazepine compared with 16 patients without seizures. There were no cases of serotonin toxicity meeting the Hunter Serotonin Toxicity Criteria. Tachycardia occurred in 27 and mild hypertension occurred in 32. The Glasgow Coma Score was < 15 in 29 and < 9 in 5 patients; three co-ingested tricyclic antidepressants and two tramadol alone (3000 mg and 900 mg). Respiratory depression occurred in 13, median dose: 2500 (IQR: 1600-3000) mg which was significantly different (p = 0.003) to patients without respiratory depression, median dose: 1000 (IQR: 750-1475) mg. Eight patients were admitted to ICU, five due to co-ingestant toxicity and three for respiratory depression.

DISCUSSION

Tramadol overdose was associated with a significant risk of seizures and respiratory depression in more severe cases, both which appear to be related to the ingested dose. There were no cases of serotonin toxicity, while opioid-like effects and adrenergic effects were prominent.

CONCLUSION

Tramadol overdose is associated with seizures and respiratory depression, but is unlikely to cause serotonin toxicity.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

Toward a systematic approach to opioid rotation

Patients requiring chronic opioid therapy may not respond to or tolerate the first opioid prescribed to them, necessitating rotation to another opioid. They may also require dose increases for a number of reasons, including worsening disease and increased pain. Dose escalation to restore analgesia using the primary opioid may lead to increased adverse events. In these patients, rotation to a different opioid at a lower-than-equivalent dose may be sufficient to maintain adequate tolerability and analgesia. In published trials and case series, opioid rotation is performed either using a predetermined substitute opioid with fixed conversion methods, or in a manner that appears to be no more systematic than trial and error. In clinical practice, opioid rotation must be performed with consideration of individual patient characteristics, comorbidities (eg, concurrent psychiatric, pulmonary, renal, or hepatic illness), and concurrent medications, using flexible dosing protocols that take into account incomplete opioid cross-tolerance. References cited in this review were identified via a search of PubMed covering all English language publications up to May 21, 2013 pertaining to opioid rotation, excluding narrative reviews, letters, and expert opinion. The search yielded a total of 129 articles, 92 of which were judged to provide relevant information and subsequently included in this review. Through a review of this literature and from the authors’ empiric experience, this review provides practical information on performing opioid rotation in clinical practice.

Racial susceptibility for QT prolongation in acute drug overdoses

BACKGROUND AND PURPOSE

QT prolongation independently predicts adverse cardiovascular events in suspected poisoning. We aimed to evaluate the association between race and drug-induced QT prolongation for patients with acute overdose.

METHODS

This was a cross-sectional observational study at two urban teaching hospitals. Consecutive adult ED patients with acute drug overdose were prospectively enrolled over a two year period. The primary outcome, long-QT, was defined using standard criteria: QTc>470 ms in females and>460 ms in males. The association between race and drug-induced QT prolongation was tested, considering several confounding variables.

RESULTS

In 472 patients analyzed (46% female, mean age 42.3), QT prolongation occurred in 12.7%. Blacks had two-fold increased odds of drug-induced QT prolongation (OR 2.01, CI 1.03-3.91) and Hispanics had 48% decreased odds of drug-induced QT prolongation (OR 0.52, CI 0.29-0.94).

CONCLUSIONS

We found significant racial susceptibility to drug-induced QT prolongation in this large urban study of acute overdoses.

Mirtazapine overdose is unlikely to cause major toxicity

OBJECTIVE

There is limited information on mirtazapine overdose, but cases of severe effects (seizures, serotonin toxicity and coma) have been reported. We aimed to investigate the clinical effects and complications of mirtazapine overdose.

METHODS

This was an observational case series of mirtazapine overdoses (> 120 mg) identified from admissions to a toxicology unit between January 1987 and August 2013. Demographic information, details of ingestion, clinical effects, ECG parameters (HR, QT and QRS), and length of stay were extracted from a clinical database.

RESULTS

From 267 mirtazapine overdoses, there were 89 single-agent mirtazapine ingestions and 178 cases where mirtazapine was taken with at least one other drug. The median age of the 89 single-agent mirtazapine ingestions was 36 years [interquartile range (IQR): 26-49 years; Range: 15-81 years]; 45 were female (51%). The median ingested dose was 420 mg (IQR: 270-750 mg; Range: 150-1350 mg) and 41 patients (46%) had a Glasgow coma score (GCS) < 15, but the minimum GCS was 10. There were no seizures, serotonin toxicity or delirium. Tachycardia occurred in 29 patients (33%) and hypertension in 32 patients (36%). The median QRS was 80 ms (Range: 80-120 ms) and there were no cases with QT prolongation. There were no arrhythmias and no deaths. The median length of stay was 14 h (IQR: 8.8-18.2 h; Range:2.2-75 h). No single-agent mirtazapine patient was admitted to intensive care. The 178 patients taking co-ingestants had more severe toxicity depending on the co-ingested drug.

CONCLUSION

Mirtazapine appears to be relatively benign in overdose, associated with tachycardia, mild hypertension and mild CNS depression not requiring intervention.