naloxone and Tachycardia--Ventricular

Several case reports suggest QT prolongation leading to ventricular arrhythmias with fatal outcome after intoxication with the μ-opioid receptor agonist and anti-diarrheal agent loperamide. The number of cases of loperamide misuse are growing due to its potential stimulating effects. Loperamide intoxications can be treated by naloxone. However, previous reports described a further QT prolongation associated with naloxone administration. Therefore, the aim of this study was to investigate the effects of loperamide and naloxone on the cardiac electrophysiology in a sensitive whole-heart model. Twenty-six hearts of New Zealand White rabbits were retrogradely perfused in a modified Langendorff apparatus. Monophasic action potentials were recorded by endo- and epicardially positioned catheters. Hearts were stimulated at different cycle lengths, thereby obtaining action potential duration at 90% of repolarization (APD

Topics: Action Potentials; Analgesics, Opioid; Animals; Antidiarrheals; Cardiac Pacing, Artificial; Cardiotoxicity; Female; Heart; Heart Rate; Isolated Heart Preparation; Loperamide; Naloxone; Narcotic Antagonists; Rabbits; Tachycardia, Ventricular; Time Factors

Naloxone is a medication with a largely benign safety profile that is frequently administered in the emergency department to patients presenting with altered mental status. Ventricular tachycardia has been reported after naloxone administration in adult patients with prior use of opiate or sympathomimetic medications. However, no such reports exist in the pediatric population or in patients who have no known history of opiate or sympathomimetic medication use. We describe a case of ventricular tachycardia after naloxone administration in a 17-year-old male with no known prior use of opiate or sympathomimetic agents who presented to the emergency department with altered mental status of unknown etiology. Emergency physicians may wish to prepare for prompt treatment of ventricular arrythmias when administering naloxone to pediatric patients presenting with altered mental status.

Topics: Adolescent; Drug Overdose; Female; Humans; Naloxone; Narcotic Antagonists; Tachycardia, Ventricular

A case of ventricular tachycardia in a 37-year-old man after ingestion of heroin and cocaine, treated with naloxone is described. The arrhythmia is attributed to unopposed sympathomemetic effects of cocaine following administration of naloxone. The pro-rhythmogenic effects of naloxone may have contributed to the arrhythmia. He was initially treated sequentially with intravenous magnesium sulphate, calcium gluconate, sodium bicarbonate and lignocaine infusion, with no resolution of the ventricular tachycardia. He was admitted to the coronary care unit and was given an amiodarone infusion which converted the rhythm to sinus rhythm. Forensic physicians administering naloxone to poly-drug abuser in a custodial setting should be aware of potentially fatal consequences which they will be unable to detect. It is recommended that all such patients should be transferred to hospital for observation and investigation.

Topics: Adult; Amiodarone; Analgesics, Opioid; Anti-Arrhythmia Agents; Cocaine; Dopamine Uptake Inhibitors; Drug Combinations; Forensic Medicine; Heroin; Humans; Injections, Intramuscular; Male; Naloxone; Narcotic Antagonists; Substance-Related Disorders; Tachycardia, Ventricular

Topics: Atrial Fibrillation; Cocaine; Heart Rate; Humans; Male; Middle Aged; Naloxone; Substance-Related Disorders; Tachycardia, Ventricular

Topics: Action Potentials; Analgesics, Opioid; Electrocardiography; Heart Rate; Humans; Morphine; Naloxone; Narcotic Antagonists; Pentazocine; Receptors, Opioid; Tachycardia, Ventricular