Loperamide as a Potential Drug of Abuse and Misuse: Fatal Overdoses at the Medical University of South Carolina

Loperamide positive deaths in Sweden 2012-2022 and Finland 2017-2022: Fatal loperamide intoxication exclusively for Sweden

Loperamide, a potent μ-opioid receptor agonist used as an antidiarrheal drug, exhibits increased bioavailability at supratherapeutic doses, causing potential central nervous system effects. Its misuse for opioid withdrawal relief and euphoria can lead to dangerously elevated blood levels, causing severe cardiac dysrhythmias and death. This study aimed to compare loperamide positive autopsy cases in Sweden and Finland after the introduction of postmortem toxicological analysis of loperamide, focusing on loperamide's role in fatalities and identifying common characteristics among those affected. All cases with detected loperamide in femoral blood at forensic autopsies in Sweden (2012-2022) and Finland (2017-2022) were included. In Sweden, loperamide was detected in 126 individuals, and in Finland, in 111 individuals. The incidence of individuals positive for loperamide in postmortem femoral blood increased steadily over the study duration in both Sweden and Finland. Loperamide related fatalities were observed exclusively in Sweden (n=80), predominantly involving younger males with histories of substance abuse, typically classified as accidental deaths. The group of loperamide nonrelated deaths in Sweden mirrored the entirety of cases in Finland. The concentration of loperamide in postmortem femoral blood was significantly higher in cases where loperamide was considered the cause of death (median 0.140 μg/g) compared to cases where loperamide contributed (median 0.080 μg/g), as well as in deaths unrelated to loperamide in both countries (Sweden: median 0.029 μg/g; Finland: median 0.010 μg/ml). The high limit of quantification for loperamide in Sweden may underestimate therapeutic users in epidemiological assessments. This study underscores the absence of loperamide misuse in Finland and indicates a rising trend of loperamide abuse in Sweden.

Loperamide Misuse Mimicking Symptoms of Severe Malnutrition

Loperamide, an oral over-the-counter μ-opioid receptor agonist used to treat diarrhea, acts primarily in the gut and, when used as recommended, has little to no systemic effect. At high doses, it may cause a "high" like other opioids. Recent literature describes an increasing incidence of loperamide misuse and overdose in the setting of the US opioid epidemic. In this case, we describe a 16-year-old with anorexia nervosa who developed dizziness, syncope, and constipation at the time of weight loss. These symptoms were originally attributed to malnutrition; however, after weight restoration, her symptoms worsened. She did not respond to initial management of suspected postural orthostatic tachycardia syndrome (POTS). She then developed acute urinary retention requiring hospitalization. Her symptoms were ultimately found to be caused by chronic surreptitious high-dose loperamide use. Her symptoms rapidly improved after cessation. This case illustrates the non-specific symptoms associated with loperamide misuse and the potential overlap with other common adolescent conditions. Adolescent medicine clinicians must be aware of the signs and symptoms of loperamide misuse as well as familiar with recommendations for both the management of acute complications and the treatment of the substance misuse.

Preventing the Abuse and Misuse of Over-the-Counter Medicines: A Survey of Community Pharmacists in Finland

BACKGROUND

Over-the-counter (OTC) medicines intended for short-term use for self-care may be abused or misused.

AIM

To explore the experiences and perceptions of community pharmacists (dispensers, pharmacists, and pharmacy owners) of the use, abuse, and misuse of OTC medicines by pharmacy customers, and to identify their perceptions of the most appropriate methods to prevent inappropriate use of OTC medicines.

METHOD

A cross-sectional national online survey to community pharmacists in Finland. A previously validated structured questionnaire was modified. Three national pharmaceutical associations were contacted to help in recruitment of their members (n = 5594, calculated target sample size n = 360). Descriptive statistical analyses were conducted.

RESULTS

In total, 442 responses were received. Most respondents strongly agreed (Md all = 5) that OTC medicines could be abused or misused; pharmacy owners were more likely to strongly agree than pharmacists (p = 0.012). Pharmacy owners were more likely to think that laxatives were liable for abuse than dispensers (p = 0.008), and that travel sickness medicines were liable for misuse than dispensers (p < 0.001) and pharmacists (p = 0.013). Patient counseling was the most commonly employed method to prevent the problem. Respondents perceived that providing training to staff about OTC medicines that can be abused (Md all = 5) was the most appropriate strategy to prevent OTC medicine abuse; pharmacy owners were more likely to strongly agree or agree of this (p = 0.005) than dispensers. Conclusion: Community pharmacists are aware of the liability of OTC medicines for the potential abuse and misuse. They employ various methods as advising and counseling the customer to support the rational use of OTC medicines.

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.

Perspectives of and Experience toward the Abuse of Antidiarrheal Drug (Loperamide) among Community Pharmacists: A Cross-Sectional Study

This study aimed to assess the ability of community pharmacists to recognize cases of loperamide abuse at the point of sale, their perspective of and experience toward potential abuse cases.

METHODS

A cross-sectional study was conducted in Jordan, using a self-administered online questionnaire. The questionnaire consisted of three main parts: demographics, the experience of pharmacists with abusers' behavior, as well as their perspectives toward loperamide abuse.

RESULTS

A total of 250 community pharmacists completed the survey, 54% (135) of which were female. Almost one-third (33.2%; 83) of the participants reported exposure to suspected cases of loperamide abuse during the last six months. Pharmacists declared that most of the suspected loperamide abusers were male (60.2%), of middle-low socioeconomic status (69.9%), and between 20 and 30 years of age (57.8%). The largest quantity (packs) of loperamide requested by a single patient was around 33.2 ± 14.9 at once. As reported by pharmacists, the suspected reasons behind loperamide abuse included 50% seeking euphoria, 17% relieving anxiety, and 33% controlling addiction (weaning off other opioids). The multivariate logistic regression analysis demonstrated a significant correlation between the male sex (OR = 1.2, 95% CI 0.12-1.59), pharmacy location in the center of Jordan (OR = 21.2, 95% CI 2.45-183.59), late-night working shift (Shift C, OR = 1.29, 95% CI 0.12-2.08), and abuse to loperamide during the last six months.

CONCLUSIONS

This study sheds light on loperamide abuse potentials, which could be influenced by different sociodemographic characteristics. Accordingly, close monitoring and thorough tackling of the abuse practices are mandated through an increase in educational and awareness campaigns about proper medication use.

Opioids in the Treatment of Chronic Idiopathic Diarrhea in Humans—A Systematic Review and Treatment Guideline

In patients with chronic idiopathic diarrhea resistant to standard treatment, opioids are often used as rescue therapy. This systematic review investigated opioid effects on gut function in chronic diarrhea. PubMed and Embase were searched regarding effects of opioid agonists on the gastrointestinal tract in humans with chronic or experimentally induced diarrhea. A total of 1472 relevant articles were identified and, after thorough evaluation, 11 clinical trials were included. Generally, studies reported a reduction in stool frequency and an increase in transit time during treatment with the opioid receptor agonists loperamide, asimadoline, casokefamide, and codeine compared with placebo. Loperamide and diphenoxylate significantly improved stool consistency compared with placebo, whereas asimadoline showed no such effects. Compared with placebo, loperamide treatment caused less abdominal pain and urgency. Asimadoline showed no significant subjective improvements, but fedotozine was superior to placebo in reducing abdominal pain and bloating in selected patients. Only two relevant studies were published within the last 20 years, and standardized endpoint measures are lacking. Most trials included few participants, and further evidence is needed from larger, prospective studies. Likewise, consensus is needed to standardize endpoints for stool frequency, transit time, and consistency to conduct future meta-analyses on opioids in management of chronic idiopathic diarrhea.

DARK Classics in Chemical Neuroscience: Loperamide

Loperamide, a popular and inexpensive over-the-counter antidiarrheal medicine, is a potent μ-opioid receptor agonist approved by the U.S. Food and Drug Administration (FDA). It has been on the market since 1976 and is relatively safe with no central nervous system-related side effects when used for a short period of time at the recommended therapeutic dose (2-8 mg/day). In recent years, loperamide has become notoriously known as the "poor man's methadone" for people with substance dependence due to the increase in loperamide overdoses from self-administered medication to treat opioid withdrawal symptoms. As a result, in 2018, the FDA decided to limit the available packaged dose of loperamide to stop prominent abuse. This review provides the synthesis and chemical properties of loperamide as well as the pharmacology and adverse effects of its use and the social effects of such abuse.

A Case Report of Loperamide-Induced Ventricular Storm

Loperamide is an easily accessible antidiarrheal medication. Unlike other medications in its class, loperamide is unique in that it causes euphoria at supratherapeutic levels due to its effect on opioid receptors. Unfortunately, with its growing abuse potential also comes increasing reports of cardiotoxicity including prolonged QT, torsades de pointes, and sudden cardiac death. We report a case of a 29-year-old female who presented with unstable arrhythmia that further progressed into electrical storm in the setting of loperamide toxicity. Due to its growing popularity and availability, it is important for clinicians to understand loperamide’s mechanisms for causing toxicity as well as how to appropriately treat its complications.

Loperamide Abuse and Its Sequelae

INTRODUCTION

Loperamide is an opioid available over the counter and in prescription form. Loperamide functions as a μ-agonist within the enteric nervous system to slow intestinal motility. Its antidiarrheal properties and primarily peripheral activity make loperamide an important tool in the management of inflammatory bowel disease.

CASE REPORT

A 42-year-old man was found unconscious in cardiac arrest, and emergency medical personnel restored normal sinus rhythm. Family reported complaints of abdominal pain and that he "went through a lot" of loperamide. In the emergency department, the patient exhibited symptoms consistent with an opioid overdose. Mental status improved after administration of naloxone, an opioid antagonist. An electrocardiogram revealed a prolonged QTc interval, which progressed into Torsades de Pointes rhythm during admission. The patient succumbed from hypoxic brain injury, and there was evidence of acute pancreatitis at autopsy. Loperamide and desmethylloperamide (loperamide metabolite) were detected in blood samples. Cause of death was ruled loperamide toxicity.

DISCUSSION

Because of reduced central nervous system activity and associated euphoria at therapeutic doses, loperamide abuse is rarely reported. This case demonstrates that an overdose on loperamide can occur in patients seeking symptom alleviation, and may mimic the presentation of opioid overdose.