Cardiac conduction disturbance after loperamide abuse

Abstract

This case series describes several patients with cardiac conduction abnormalities and life-threatening ventricular arrhythmias temporally related to loperamide abuse. With the recent efforts to restrict the diversion of prescription opioids, increasing abuse of loperamide as an opioid substitute may be seen. Toxicologists should be aware of these risks and we urge all clinicians to report such cases to FDA Medwatch(®).

Conduction Disturbances and Ventricular Arrhythmias Associated with High- Dose Loperamide

“…The patient had a structurally normal heart, and literature review confirmed identical presentations associated with loperamide overdose. While other aforementioned electrocardiographic abnormalities have been described in scant case reports [3][4][5], to our knowledge, this is the first case report of this agent unmasking a Brugada pattern. Previous reports describe markedly elevated serum loperamide concentrations with presentations including life-threatening ventricular tachyarrhythmias, and varying degrees of QRS and QTc prolongation.…”

“…Marraffa et al [3] 26 y/o PMH opioid abuse. Recurrent syncope, TdP requiring cardioversion, QTc>700 ms 100-150 mg loperamide with 400 mg cimetidine daily for 7 days Started on isoproterenol infusion initially.…”

“…Spinner et al [5] The QT interval prolongation related to loperamide has been attributed to inhibition of the human ether-a-go-go-related gene (hERG) responsible for the rapid delayed rectifier potassium current (Ikr); a known mechanism of many QT interval prolonging drugs as well as congenital long QT syndrome type 2 (LQTS2) [3,[9][10][11]. This current mediates cardiac myocyte repolarization and terminates the action potential; hERG inhibition leads to delayed repolarization, predisposes to early after-depolarizations (EADs), heterogeneous myocardial repolarization, and TdP [10].…”

“…However, web-forum analyses over recent years reveal increased discussion of extra-medical uses of loperamide to alleviate opioid-withdrawal symptoms and to achieve euphoria [2]. Further, a series of recentlypublished cases reveals an association with recreational loperamide use (and significantly elevated serum concentrations) with electrocardiographic derangements including QRS complex and QT interval prolongation thought to be related to sodium channel blockade, and potassium channel blockade, respectively, as well as monomorphic ventricular tachycardia and torsades de pointes (TdP) [3][4][5]. We present a case of high-dose loperamide ingestion leading to bradyarrhythmias, prolongation of the QRS complex and QTc interval, unmasking of Type I Brugada pattern, and episodes of TdP.…”

Ventricular fibrillation due to overdose of loperamide, the “poor man’s methadone”

“…An overdrive pacemaker was used to achieve the same strategy. Lidocaine was added to stabilize the ventricular membrane [14,15]. After the initial usage during a VF arrest, amiodarone use was avoided because of the risk of QT prolongation.…”