Loperamide is a μ-opioid receptor agonist with antidiarrhoeal effects. It is considered to have a low abuse potential because of substantial first-pass metabolism and P-glycoprotein-mediated efflux at the level of the blood-brain barrier. Previous case reports have described that high dosage of loperamide can induce an opioid-like effect on the central nervous system. The most common presentation of loperamide intoxication is syncope which is caused by serious cardiac dysrhythmia and can lead to death. Therefore, it was decided to analyze whether drug prescriptions in the prescription drug database from The Directorate of Health would indicate loperamide misuse in Iceland from 2006-2017. In total 94 individuals used more than one DDD (10 mg) and 17 individuals used more than two DDD (20 mg), if taken daily over one year. These results indicate that loperamide is being used excessively but the reason for each prescription and the total amount sold over the counter is unknown. Increased surveillance and decreased availability of prescription opioids might possibly boost the usage of drugs with similar function such as loperamide. Loperamide overdose can result in serious adverse effects and thus, it is important to inform healthcare employees about such severe consequences.

Figure 1: Quotes from internet-forums, written by individuals who describe their experience of loperamide abuse. Brackets means that a part of the sentence has been removed.

*Losec is the same as omeprazole. **Percs is the same as oxycodone.

Figure 2:  List of drugs that could increase loperamide effects on the central nervous system. Drugs that are inhibitors and/or substrates of the efflux pump P-glycoprotein are shown in the circles. Inhibitors of CYP3A4 are underlined. The list is not exhaustive.

Figure 3: The age and gender distribution of those who received >400 DDD of loperamide per year divided in two groups, those who were prescribed 401-799 DDD and 800 DDD). A DDD is the assumed average maintenance dose per day for a drug used for its main indication in adults. For loperamide one DDD is 10 mg.

Figure 4: A column graph showing the total DDD and a line graph showing the number of individuals who received >400 DDD of loperamide from 2006-2017.  Since total DDD is given for each individual each year it is neither possible to assume the amount sold over the counter nor the exact dosages that were prescribed each time. A DDD is the assumed average maintenance dose per day for a drug used for its main indication in adults. For loperamide one DDD is 10 mg.

Figure 5: A line graph showing loperamide use of the 6 individuals who at some point used ≥1200 DDD/year (or >32mg/day if taken daily over the year). Each line represents one individual and the fluctuation in DDD each year. If divided by 365 days the highest daily dosage of each individual would be 120,5 mg, 67,4 mg, 40 mg, 37,3 mg, 36,2 mg og 32,9 mg. A DDD is the assumed average maintenance dose per day for a drug used for its main indication in adults. For loperamide one DDD is 10 mg but the maximum daily dose is 16 mg.