What is the role of loperamide in IBS?
Loperamide is a synthetic peripheral opioid agonist that reduces gut transit. By binding to the μ opioid receptors on the myenteric neurons in the upper and lower bowel, loperamide reduces gut motility, which allows for greater fluid absorption and improved stool consistency. Loperamide does not cross the blood-brain barrier at standard doses, and therefore does not have central nervous system side effects, such as sedation or addiction. Most patients with IBS experience reduction in diarrhea and frequency, as well as improvement in stool consistency. Loperamide 2 to 4 mg each morning after the initial bowel movement and before social events can reduce undesirable urges to defecate, and increases confidence and willingness to engage in social activities.