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Canadian Journal of Cardiology

Loperamide Cardiac Toxicity: Pathophysiology, Presentation, and Management

Published:April 14, 2022DOI:https://doi.org/10.1016/j.cjca.2022.04.005

      Abstract

      Loperamide is a nonprescription medication commonly used to treat diarrhea. Although it is an opioid, it is very poorly absorbed and well tolerated, with no systemic toxicity at standard doses. In recent years, however, loperamide has been ingested in very large quantities, sometimes with concomitant medications intended to enhance absorption and/or passage across the blood-brain barrier. Most people who misuse loperamide do so for its euphoric effects or to treat symptoms of opioid withdrawal. In addition to the risks of central opioid toxicity, this practice can result in potentially fatal cardiac dysrhythmias, because very high concentrations of loperamide alter the cardiac action potential. Patients will often present with recurrent, unexplained syncope accompanied with marked electrocardiographic abnormalities including QT-interval prolongation, widening of the QRS complex, and dysrhythmias such as torsades de pointes. Treatment involves early identification and discontinuation of loperamide, reversal of central opioid effects if present, and interventions aimed at addressing any cardiac conduction abnormalities. In addition, if there is an underlying opioid use disorder, efforts should be made to refer to specialised addictions care and initiate opioid agonist therapy when appropriate. We review the pharmacology of loperamide and the clinical presentation, pathophysiology, and suggested management of loperamide cardiac toxicity.

      Résumé

      Le lopéramide est un médicament en vente libre couramment utilisé pour traiter la diarrhée. Bien qu'il s'agisse d'un opioïde, il est très peu absorbé et bien toléré, sans toxicité systémique aux doses standard. Ces dernières années, cependant, le lopéramide a été ingéré en très grandes quantités, parfois concomitamment avec des médicaments destinés à améliorer l'absorption et/ou le passage de la barrière hémato-encéphalique. La plupart des personnes qui abusent du lopéramide le font pour ses effets euphorisants ou pour traiter les symptômes du sevrage des opioïdes. Outre les risques de toxicité centrale des opioïdes, cette pratique peut entraîner des dysrythmies cardiaques potentiellement mortelles, car de très fortes concentrations de lopéramide modifient le potentiel d'action cardiaque. Les patients présentent souvent des syncopes récurrentes et inexpliquées, accompagnées d'anomalies électrocardiographiques marquées, notamment un allongement de l'intervalle QT, un élargissement du complexe QRS et des troubles du rythme tels que des torsades de pointes. Le traitement implique l'identification précoce et l'arrêt du lopéramide, l'inversion des effets centraux des opioïdes s'ils sont présents, et des interventions visant à traiter toute anomalie de la conduction cardiaque. En outre, s'il existe un déséquilibre sous-jacent de la consommation d'opioïdes, il faut s'efforcer d'orienter le patient vers des soins spécialisés en toxicomanie et instaurer un traitement par agoniste opioïde le cas échéant. Nous passons en revue la pharmacologie du lopéramide ainsi que le tableau clinique, la pathophysiologie et la prise en charge suggérée de la toxicité cardiaque du lopéramide.
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