Adverse event detection using the FDA post-marketing drug safety surveillance system: Cardiotoxicity associated with loperamide abuse and misuse

Loperamide-Induced Torsades de Pointes

Loperamide is a readily available, over-the-counter medication used to treat diarrhea. At therapeutic doses, loperamide exerts its effects mainly on the intestinal opioid receptors with minimal psychoactive effects; however, at supratherapeutic doses, it reaches central opioid receptors. With tighter regulations on opioid prescriptions, loperamide has emerged as a popular drug of abuse among opioid users. At supratherapeutic doses, loperamide can cause severe cardiac toxicity, resulting in wide QRS rhythms, severe bradycardia, prolonged QTc, polymorphic ventricular tachycardia, and cardiac arrest. We present the case of a 27-year-old female with a history of heroin abuse who suffered torsades de pointes resulting in cardiac arrest in the setting of a loperamide overdose.

Drug-induced QT prolongation and torsade de pointes: a real-world pharmacovigilance study using the FDA Adverse Event Reporting System database

Introduction: Drug-induced QT prolongation and (or) Torsade de Pointes (TdP) is a well-known serious adverse reaction (ADR) for some drugs, but the widely recognized comprehensive landscape of culprit-drug of QT prolongation and TdP is currently lacking. Aim: To identify the top drugs reported in association with QT prolongation and TdP and provide information for clinical practice. Method: We reviewed the reports related to QT prolongation and TdP in the FDA Adverse Event Reporting System (FAERS) database from January 1, 2004 to December 31, 2022, and summarized a potential causative drug list accordingly. Based on this drug list, the most frequently reported causative drugs and drug classes of QT prolongation and TdP were counted, and the disproportionality analysis for all the drugs was conducted to in detect ADR signal. Furthermore, according to the positive-negative distribution of ADR signal, we integrated the risk characteristic of QT prolongation and TdP in different drugs and drug class. Results: A total of 42,713 reports in FAERS database were considered to be associated with QT prolongation and TdP from 2004 to 2022, in which 1,088 drugs were reported as potential culprit-drugs, and the largest number of drugs belonged to antineoplastics. On the whole, furosemide was the most frequently reported drugs followed by acetylsalicylic acid, quetiapine, citalopram, metoprolol. In terms of drug classes, psycholeptics was the most frequently reported drug classes followed by psychoanaleptics, analgesics, beta blocking agents, drugs for acid related disorders. In disproportionality analysis, 612 drugs showed at least one positive ADR signals, while citalopram, ondansetron, escitalopram, loperamide, and promethazine were the drug with the maximum number of positive ADR signals. However, the positive-negative distribution of ADR signals between different drug classes showed great differences, representing the overall risk difference of different drug classes. Conclusion: Our study provided a real-world overview of QT prolongation and TdP to drugs, and the presentation of the potential culprit-drug list, the proportion of reports, the detection results of ADR signals, and the distribution characteristics of ADR signals may help understand the safety profile of drugs and optimize clinical practice.

Loperamide cases reported to United States poison centers, 2010-2022

BACKGROUND

Intentional use of high doses of loperamide has been linked to serious cardiac toxicity. The objective of this study is to investigate the characteristics and trends of loperamide cases reported to United States (US) poison centers and to evaluate the changes in reported loperamide cases following US Food and Drug Administration (FDA) warnings, labeling requirements, and packaging restrictions for loperamide starting in 2016, with an emphasis on intentional exposures.

METHODS

Data from the National Poison Data System were analyzed.

RESULTS

There were 12,987 cases reported to US poison centers from 2010 to 2022, for which, loperamide was the most likely substance responsible for observed clinical effects. Although 46.1% of these cases were associated with minor or no effect, 13.4% resulted in a serious medical outcome, including 59 deaths (0.5%). Eight percent (8.1%) of cases were admitted to a critical care unit and 5.0% were admitted to a non-critical care unit. Among cases with a serious medical outcome, most were associated with loperamide abuse (38.0%), intentional-misuse (15.7%), or suspected suicide (27.5%). The majority (60.0%; n = 33) of fatalities were related to abuse, followed by suspected suicide (20.0%; n = 11) and intentional-misuse (5.5%, n = 3). The rate of loperamide cases per 100,000 US population reported to US PCs decreased from 0.44 in 2010 to 0.36 in 2015 (p = 0.0290), followed by an increase to 0.46 in 2017 (p = 0.0013), and then a trend reversal with a decrease to 0.28 in 2022 (p < 0.0001). The rate of serious medical outcomes related to loperamide increased from 0.03 in 2010 to 0.05 in 2015 (p = 0.0109), which subsequently increased rapidly to 0.11 in 2017 (p < 0.0001), and then demonstrated a trend reversal and decreased to 0.04 in 2022 (p < 0.0001).

CONCLUSIONS

FDA warnings, labeling requirements, and packaging restrictions may have contributed to the observed trend reversal and decrease in reports to US poison centers of loperamide cases related to intentional misuse, abuse, and suspected suicide. This demonstrates the potential positive effect that regulatory actions may have on public health. These findings contribute to the evidence supporting the application of similar prevention efforts to reduce poisoning from other medications associated with intentional misuse, abuse, and suicide.

The Potential Mechanisms behind Loperamide-Induced Cardiac Arrhythmias Associated with Human Abuse and Extreme Overdose

Loperamide has been a safe and effective treatment for diarrhea for many years. However, many cases of cardiotoxicity with intentional abuse of loperamide ingestion have recently been reported. We evaluated loperamide in in vitro and in vivo cardiac safety models to understand the mechanisms for this cardiotoxicity. Loperamide slowed conduction (QRS-duration) starting at 0.3 µM [~1200-fold (×) its human Free Therapeutic Plasma Concentration; FTPC] and reduced the QT-interval and caused cardiac arrhythmias starting at 3 µM (~12,000× FTPC) in an isolated rabbit ventricular-wedge model. Loperamide also slowed conduction and elicited Type II/III A-V block in anesthetized guinea pigs at overdose exposures of 879× and 3802× FTPC. In ion-channel studies, loperamide inhibited hERG (IKr), INa, and ICa currents with IC50 values of 0.390 µM, 0.526 µM, and 4.091 µM, respectively (i.e., >1560× FTPC). Additionally, in silico trials in human ventricular action potential models based on these IC50s confirmed that loperamide has large safety margins at therapeutic exposures (≤600× FTPC) and confirmed repolarization abnormalities in the case of extreme doses of loperamide. The studies confirmed the large safety margin for the therapeutic use of loperamide but revealed that at the extreme exposure levels observed in human overdose, loperamide can cause a combination of conduction slowing and alterations in repolarization time, resulting in cardiac proarrhythmia. Loperamide's inhibition of the INa channel and hERG-mediated IKr are the most likely basis for this cardiac electrophysiological toxicity at overdose exposures. The cardiac toxic effects of loperamide at the overdoses could be aggravated by co-medication with other drug(s) causing ion channel inhibition.

Medical Therapies for Diarrhea-Predominant Irritable Bowel Syndrome

Diarrhea-predominant irritable bowel syndrome is a common functional gastrointestinal disorder that manifests with abdominal pain and diarrheal bowel patterns, without structural explanation. Diarrhea-predominant irritable bowel syndrome is a heterogeneous condition resulting from diverse pathophysiologic processes. Treatment strategies with varied mechanisms of action are beneficial in its management. The clinician must become familiar with a multi-dimensional approach to irritable bowel syndrome. The 3 approved medications are central to disease management. Effective treatment uses off-label medications and emerging therapies and a growing number of over-the-counter and supplemental agents to optimize symptom improvement for the patient with diarrhea-predominant irritable bowel syndrome.

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.

Toward a broader view of mechanisms of drug cardiotoxicity

Cardiotoxicity, defined as toxicity that affects the heart, is one of the most common adverse drug effects. Numerous drugs have been shown to have the potential to induce lethal arrhythmias by affecting cardiac electrophysiology, which is the focus of current preclinical testing. However, a substantial number of drugs can also affect cardiac function beyond electrophysiology. Within this broader sense of cardiotoxicity, this review discusses the key drug-protein interactions known to be involved in cardiotoxic drug response. We cover adverse effects of anticancer, central nervous system, genitourinary system, gastrointestinal, antihistaminic, anti-inflammatory, and anti-infective agents, illustrating that many share mechanisms of cardiotoxicity, including contractility, mitochondrial function, and cellular signaling.

Peripherally acting opioid analgesics and peripherally-induced analgesia

The management of pain, particularly chronic pain, is still an area of medical need. In this context, opioids remain a gold standard for the treatment of pain. However, significant side effects, mainly of central origin, limit their clinical use. Here, we review recent progress to improve the therapeutic and safety profiles of opioids for pain management. Characterization of peripheral opioid-mediated pain mechanisms have been a key component of this process. Several studies identified peripheral µ, δ, and κ opioid receptors (MOR, DOR, and KOR, respectively) and nociceptin/orphanin FQ (NOP) receptors as significant players of opioid-mediated antinociception, able to achieve clinically significant effects independently of any central action. Following this, particularly from a medicinal chemistry point of view, main efforts have been directed towards the peripheralization of opioid receptor agonists with the objective of optimizing receptor activity and minimizing central exposure and the associated undesired effects. These activities have allowed the characterization of a great variety of compounds and investigational drugs that show low central nervous system (CNS) penetration (and therefore a reduced side effect profile) yet maintaining the desired opioid-related peripheral antinociceptive activity. These include highly hydrophilic/amphiphilic and massive molecules unable to easily cross lipid membranes, substrates of glycoprotein P (a extrusion pump that avoids CNS penetration), nanocarriers that release the analgesic agent at the site of inflammation and pain, and pH-sensitive opioid agonists that selectively activate at those sites (and represent a new pharmacodynamic paradigm). Hopefully, patients with pain will benefit soon from the incorporation of these new entities.

Pharmacovigilance Assessment of Cardiac Implications of Nicotine Replacement Therapy Among Smokers

PURPOSE

The purpose of this quantitative comparative study was to examine the possible relationship between nicotine replacement therapy (NRT) and cardiac disorder risk by comparing the rates of cardiac disorder risk of NRT with cardiac disorder risk of non-replacement drugs among smokers seeking smoking cessation.

METHODS

The study used retrospective quantitative design, which involved the collection of secondary data from the adverse event reporting system (FAERS) database of the U.S Food and Drug Administration (FDA). Rates of cardiac disorder were compared between the NRT group and non- NRT (varenicline and bupropion) group. Statistical analyses involved using a 2x2 contingency table and logistic regression to calculate odds ratio (reporting odds ratio (ROR)).

RESULTS AND DISCUSSION

Unadjusted ROR was 0.45 (95% confidence interval [CI] 0.28, 0.70). With age and sex as confounding factors, the smokers in the NRT group still had lower odds of having cardiac disorder risk than the non-NRT group (adjusted ROR=0.44, 95% CI 0.28, 0.70).

CONCLUSION

Our study findings showed lower cardiac disorder risk with the NRT group compared to the non-NRT (varenicline and bupropion) group. While the study did not aim to undermine either using NRT or non-NRT for smoking cessation therapy to prevent smoking illness, the study results offer informed findings that could potentially improve current smoking cessation management using NRT intervention among smokers and enhance smokers' health outcome. Despite the negative signal detection of cardiac disorder risk with NRT as compared to non-NRT in final findings, we still recommend further research on the causal relationship between NRT and non-NRT and cardiac disorder risk.

Loperamide overdose causing torsades de pointes and requiring Impella temporary mechanical support: a case report

Background

Loperamide is a widely available oral μ-opioid receptor agonist, and loperamide abuse is increasing by those seeking intoxication. Loperamide has potent QTc-prolonging properties, placing patients at risk for ventricular arrhythmias and sudden cardiac death.

Case summary

A 23-year-old woman was found to be in pulseless ventricular fibrillation with a QTc of 554 ms and received multiple defibrillations and IV lidocaine. Her toxicology studies were negative. She subsequently experienced multiple episodes of torsades de pointes and was found to be in cardiogenic shock with a left ventricular ejection fraction of 5%. Following multiple defibrillations, an Impella® mechanical circulatory support device was placed, and she was given IV magnesium and IV lidocaine. After mechanical circulatory support was withdrawn, she experienced major bleeding and was found to have a deep vein thrombosis, bilateral radial artery thrombosis, and multiple pulmonary embolisms in the setting of heparin-induced thrombocytopenia. After stabilizing, she admitted to taking 80 tablets of loperamide 2 mg in pursuit of euphoria.

Discussion

Loperamide is an increasingly popular agent of abuse. Loperamide-associated ventricular arrhythmias are rare with normal doses but more common with high doses, chronic ingestion, or interacting medications. Loperamide cardiotoxicity may be prolonged due to a long half-life and accumulation. Loperamide abuse may be under-recognized, leading to delays in treatment. Intravenous fluids, magnesium supplementation, chronotropes, transcutaneous or transvenous pacing, and defibrillation may be helpful in mitigating loperamide-associated polymorphic ventricular tachycardia. Clinicians should monitor for drug interactions in patients taking loperamide and screen for electrocardiographic abnormalities in those taking chronic or high-dose loperamide.

Radiographic dose-dependency study of loperamide effects on gastrointestinal motor function in the rat. Temporal relationship with nausea-like behavior

BACKGROUND

Loperamide is a potent mu opioid receptor agonist available over the counter to treat diarrhea. Although at therapeutic doses loperamide is devoid of central effects, it may exert them if used at high doses or combined with drugs that increase its systemic and/or central bioavailability. Recently, public health and scientific interest on loperamide has increased due to a growing trend of misuse and abuse, and consequent reports on its toxicity. Our aim was to evaluate in the rat the effects of increasing loperamide doses, with increasing likelihood to induce central effects, on gastrointestinal motor function (including gastric dysmotility and nausea-like behavior).

METHODS

Male Wistar rats received an intraperitoneal injection of vehicle or loperamide (0.1, 1, or 10 mg kg^-1 ). Three sets of experiments were performed to evaluate: (a) central effects (somatic nociceptive thresholds, immobility time, core temperature, spontaneous locomotor activity); (b) general gastrointestinal motility (serial X-rays were taken 0-8 hours after intragastric barium administration and analyzed semiquantitatively, morphometrically, and densitometrically); and (c) bedding intake (a rodent indirect marker of nausea). Animals from sets 1 and 3 were used to evaluate gastric dysmotility ex vivo at 2 and 4 hours after administration, respectively.

KEY RESULTS

Loperamide significantly induced antinociception, hypothermia, and hypolocomotion (but not catalepsy) at high doses and dose-dependently reduced gastrointestinal motor function, with the intestine exhibiting higher sensitivity than the stomach. Whereas bedding intake occurred early and transiently, gastric dysmotility was much more persistent.

CONCLUSIONS AND INFERENCES

Our results suggest that loperamide-induced nausea and gastric dysmotility might be temporally dissociated.

Is there such a thing as a 'lope' dope? Analysis of loperamide-related European Medicines Agency (EMA) pharmacovigilance database reports

Background

Among over-the-counter (OTC) drugs, loperamide has recently emerged for its potential of misuse and cardiotoxicity issues. Hence, we aimed here at assessing the loperamide-related cases being reported to the EMA's EudraVigilance (EV) database.

Methods

All spontaneous EV reports relating to loperamide misuse/abuse/dependence/withdrawal and cardiotoxicity issues were here retrieved, performing a descriptive analysis.

Findings

During the years 2005–2017, EV collected a number of 1,983 (out of a total of 7,895; 25.11%) loperamide-related misuse/abuse/dependence/withdrawal adverse drug reaction (ADR) reports, with a progressively increasing trend since 2014. Most cases were classified as drug use disorder (37.4%) or intentional overdose (25.4%). Loperamide was used on its own in 41.9% of cases; remaining, polydrug, cases included antidepressants; benzodiazepines; and other OTCs. Some 1,085 (1,085/7,895 = 13.7%) cardiovascular ADRs were reported, being conduction abnormalities and EKG alterations the most frequently identified.

Conclusions

EV data may support the levels of concern relating to loperamide potential of abuse and associated cardiotoxicity issues.

Review article: an analysis of safety profiles of treatments for diarrhoea-predominant irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is multifactorial in nature, and a wide range of therapies is available to manage symptoms of this common disorder.

AIM

To provide an overview of the safety of interventions that may be used to manage patients with diarrhoea-predominant IBS (IBS-D).

METHODS

Medline and Embase database searches (through 02 May 2018) to identify clinical studies that evaluated treatment safety and/or efficacy in adults with IBS-D.

RESULTS

IBS-D treatments include dietary modification, probiotics, serotonin receptor antagonists, opioid receptor agonists and antagonists, nonsystemic antibiotics, bile acid sequestrants, antidepressants, and complementary and alternative therapies. These treatments vary in administration frequency (eg, daily; short-course therapy) and target various pathophysiologic factors. Safety profiles vary considerably by treatment among IBS-D therapies. The number needed to harm (defined as the number of patients treated to encounter an adverse event) was lowest (worse) for antidepressants (8.5) and highest (best) for probiotics (35), and the number needed to harm (defined as the number of patients who discontinued due to an adverse event) was lowest for tricyclic antidepressants (9) and highest for rifaximin (8971). Notable safety concerns with IBS-D treatments include pancreatitis with eluxadoline, ischaemic colitis and serious complications of constipation with alosetron, and cardiac adverse events with loperamide and tricyclic antidepressants. Treatment decisions need to account for medication risks and adverse events for each patient.

CONCLUSIONS

Multiple treatment options are now available for patients with IBS-D. However, the safety profiles of these agents vary widely by number needed to harm value. Providers should consider both safety and efficacy of a specific intervention when determining how best to manage patients' IBS-D symptoms.

Bradycardia and Syncope in a Patient Presenting With Loperamide Abuse

Loperamide is an antidiarrheal agent available as an inexpensive over-the-counter (OTC) medication. In general, it is considered to be safe, but lately, loperamide drug abuse has been reported due to its opioid properties. When used in high doses, several harmful effects including cardiotoxicity, central nervous system (CNS) and respiratory depression have been reported. This prompted the FDA to release a warning in 2016 regarding the arrhythmogenic potential of loperamide. We present a case of a 32-year-old male with a history of polysubstance abuse who presented to the emergency department (ED) requesting “detoxification” from loperamide. The patient complained of opiate withdrawal symptoms including chills, nausea, vomiting, constipation, and abdominal cramps thought to be secondary to the abuse of loperamide. He was found to have right bundle branch block (RBBB) and bradycardia with a heart rate (HR) of 51 beats per min (bpm). He also reported an unexplained syncopal episode, one day prior to visiting the ED. In the current case report, we discuss loperamide abuse, its harmful effects, and management.

Abuse of Prescription Drugs in the Context of Novel Psychoactive Substances (NPS): A Systematic Review

Recently, a range of prescription and over-the-counter drugs have been reportedly used as Novel Psychoactive Substances (NPS), due to their potential for abuse resulting from their high dosage/idiosyncratic methods of self-administration. This paper provides a systematic review of the topic, focusing on a range of medications which have emerged as being used recreationally, either on their own or in combination with NPS. Among gabapentinoids, pregabalin may present with higher addictive liability levels than gabapentin, with pregabalin being mostly identified in the context of opioid, polydrug intake. For antidepressants, their dopaminergic, stimulant-like, bupropion activities may explain their recreational value and diversion from the therapeutic intended use. In some vulnerable clients, a high dosage of venlafaxine (‘baby ecstasy’) is ingested for recreational purposes, whilst the occurrence of a clinically-relevant withdrawal syndrome may be a significant issue for all venlafaxine-treated patients. Considering second generation antipsychotics, olanzapine appears to be ingested at very large dosages as an ‘ideal trip terminator’, whilst the immediate-release quetiapine formulation may possess proper abuse liability levels. Within the image- and performance- enhancing drugs (IPEDs) group, the beta-2 agonist clenbuterol (‘size zero pill’) is reported to be self-administered for aggressive slimming purposes. Finally, high/very high dosage ingestion of the antidiarrhoeal loperamide has shown recent increasing levels of popularity due to its central recreational, anti-withdrawal, opiatergic effects. The emerging abuse of prescription drugs within the context of a rapidly modifying drug scenario represents a challenge for psychiatry, public health and drug-control policies.

Risk of Pancreatitis Following Treatment of Irritable Bowel Syndrome With Eluxadoline

BACKGROUND & AIMS

The Food and Drug Administration approved eluxadoline for the treatment of diarrhea-predominant irritable bowel syndrome despite cases of pancreatitis in early stage trials. We investigated the frequency of pancreatitis attributed to eluxadoline in postmarketing surveillance.

METHODS

We extracted reports on eluxadoline submitted to the Federal Adverse Event Reporting System from January through September 2016. We collected data on patient age and sex, event date, reporting entity (consumer, physician, pharmacist, legal worker, or other), medications, dosages, presumed role in the event (coinciding, primary, or secondary suspect), treatment indication, and outcome (death, life threatening, hospitalization, disability, or other).We compared data for eluxadoline with data from antidiarrheals, oxycodone, and rifaximin using the κ² test, Kruskal-Wallis rank test, and analysis of variance; findings with P < .05 were considered statistically significant.

RESULTS

Pancreatitis accounted for 16.4% of the 597 reports of adverse events linked to eluxadoline; 53 cases required hospitalization. Pancreatitis was listed as treatment complication of other agents in significantly lower proportions of cases (loperamide, 0.3%; diphenoxylate, 0.4%; oxycodone, 0.2%; rifaximin, 0.5%), with 75% of these submissions not considering the agent as causal.

CONCLUSIONS

In an analysis of reports on eluxadoline submitted to the Federal Adverse Event Reporting System, we confirmed a previously reported risk of pancreatitis associated with eluxadoline. The need for hospitalization in at least half of these instances and a recent report of 2 fatalities should prompt reassessments of the agent's risk-benefit ratio.

When good times go bad: managing 'legal high' complications in the emergency department

Patients can use numerous drugs that exist outside of existing regulatory statutes in order to get "legal highs." Legal psychoactive substances represent a challenge to the emergency medicine physician due to the sheer number of available agents, their multiple toxidromes and presentations, their escaping traditional methods of analysis, and the reluctance of patients to divulge their use of these agents. This paper endeavors to cover a wide variety of "legal highs," or uncontrolled psychoactive substances that may have abuse potential and may result in serious toxicity. These agents include not only some novel psychoactive substances aka "designer drugs," but also a wide variety of over-the-counter medications, herbal supplements, and even a household culinary spice. The care of patients in the emergency department who have used "legal high" substances is challenging. Patients may misunderstand the substance they have been exposed to, there are rarely any readily available laboratory confirmatory tests for these substances, and the exact substances being abused may change on a near-daily basis. This review will attempt to group legal agents into expected toxidromes and discuss associated common clinical manifestations and management. A focus on aggressive symptom-based supportive care as well as management of end-organ dysfunction is the mainstay of treatment for these patients in the emergency department.

Ventricular fibrillation due to overdose of loperamide, the "poor man's methadone"

Loperamide is an over-the-counter antidiarrheal agent that is considered by many patients to be safe, but has been used as a drug of abuse due to its opioid properties. However, cardiotoxicity has been reported, prompting the FDA to release a warning regarding the arrhythmogenic potential of loperamide. We present a case of a 38-year-old female presenting with cardiac arrest thought to be secondary to abuse of the loperamide that she was using to alleviate the heroin withdrawal symptoms. Cardiac ischemia and other drug toxicities were ruled out. Loperamide induces QTc prolongation and cardiac dysrhythmias. She had recurrent ventricular arrhythmias with multiple cardiac arrests. The persistence of the cardiotoxicity for a longer duration than previously reported in the literature is unique in this clinical presentation. We also highlight the potential mechanisms for loperamide cardiotoxicity and its challenging management.

Abbreviations: ACLS: Advanced cardiac life support; GI: Gastrointestinal

Intentional Misuse and Abuse of Loperamide: A New Look at a Drug with "Low Abuse Potential"

BACKGROUND

Despite its opioid properties, loperamide has long been thought to have low abuse potential due to its poor absorption from the gastrointestinal tract and limited potential to cross the blood-brain barrier. A recent patient reportedly taking loperamide to avoid heroin withdrawal symptoms, at doses approximately 100 times those recommended, directed our attention to this issue.

OBJECTIVES

1) Investigate number of cases of intentional loperamide abuse and misuse reported to poison centers between 2009 and 2015; 2) Compile reports of clinical effects of loperamide abuse; and 3) Search for evidence of increasing Internet interest in the central opioid effects of loperamide.

METHODS

For the years 2009 thru 2015, we reviewed exposure calls related to misuse/abuse of loperamide in the Texas Poison Center Network's database and the National Poison Data System. We used Google trend analysis to detect evidence of increased Internet interest in the illicit use of loperamide.

RESULTS

Between 2009 and 2015, the number of misuse/abuse calls related to loperamide alone nearly doubled, with about one-third of cases occurring in teens and young adults in their 20s. Of particular concern are reports of significant cardiotoxic effects (∼18% of cases), including conduction defects and various dysrhythmias, sometimes leading to death. Google Trends analysis demonstrates an increasing number of searches for "loperamide high" and "loperamide withdrawal" beginning in 2011.

CONCLUSIONS

Loperamide misuse/abuse seems to be on the rise. Given its propensity to induce conduction disturbances and dysrhythmias at very high doses, emergency physicians should be vigilant for this form of drug abuse.