Loperamide (Imodium), a common over-the-counter antidiarrheal drug and opioid derivative, is formulated to act upon intestinal opioid receptors, but at high doses well above recommended dosages for diarrhea, loperamide crosses the blood-brain barrier and reaches central opioid receptors in the brain, resulting in euphoria and respiratory depression.
Federal health officials are investigating reports of overdoses and deaths involving widely used anti-diarrhea drugs, which contain loperamide. At least one case of Loperamide overdose and death has been classified as a poor man’s methadone.
The Food and Drug Administration warned doctors and patients Tuesday that over-the-counter and prescription medications, including Imodium, can cause potentially deadly heart problems when taken in large doses. The agency has received 31 reports of people hospitalized due to the heart problems, including 10 deaths over the last 39 years.
But national poison centers report a 71 percent increase in calls involving the drug between 2011 and 2014.
The primary ingredient in the drugs, loperamide, is intended to control diarrhea. Loperamide is an opioid-receptor agonist and acts on the μ-opioid receptors in the myenteric plexus of the large intestine. Loperamide works similarly to morphine — decreasing the activity of the myenteric plexus, which decreases the tone of the longitudinal and circular smooth muscles of the intestinal wall. But the loperamide, when taken at supratherapeutic oral doses, can reportedly cause euphoric highs, similar to opioid drugs like morphine. Some critics deny that loperamide can cause euphoric highs because its biochemical nature is blocked from the blood brain barrier and because its concentration is greatly reduced by metabolism in the liver after entering the hepatic portal system from the digestive system. Critics also state that people are only abusing loperamide to ease withdrawal symptoms by self-medicating to get away from addiction. Abuse is probably occurring in both cases — for a high, and for a cure.
Oral loperamide abuse as an opioid substitute has been increasing among patients attempting to self-treat their opioid addiction. Ventricular dysrhythmias and prolongation of the QRS duration and QTc interval have been reported after oral loperamide abuse.
In one death, loperamide was suspected because toxicity tests detected chlorine, which is included in the molecular formula of loperamide (C29H33ClN2O2)
When originally approved for medical use in the United States, loperamide was considered a narcotic and was put into Schedule II of the Controlled Substances Act 1970. Loperamide was transferred to Schedule V on July 17, 1977 and then decontrolled as of November 3, 1982.
Dierksen J1, Gonsoulin M, Walterscheid JP. Poor Man’s Methadone: A Case Report of Loperamide Toxicity. Am J Forensic Med Pathol. 2015 Dec;36(4):268-70.
Eggleston W1, Clark KH2, Marraffa JM3. Loperamide Abuse Associated With Cardiac Dysrhythmia and Death. Ann Emerg Med. 2016 Apr 26. pii: S0196-0644(16)30052-X.
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