Antimotility agents are drugs used to alleviate the symptoms of diarrhea. These include loperamide (Imodium), bismuth subsalicylate (Pepto-Bismol), [1] diphenoxylate with atropine (Lomotil), and opiates such as paregoric, tincture of opium, codeine, and morphine. In diarrhea caused by invasive pathogens such as Salmonella , Shigella , and Campylobacter , the use of such agents has generally been strongly discouraged, though evidence is lacking that they are harmful when administered in combination with antibiotics in Clostridioides difficile cases. [2] Use of antimotility agents in children and the elderly has also been discouraged in treatment of EHEC (Shiga-like toxin producing Escherichia coli ) due to an increased rate of hemolytic uremic syndrome. [3]
Loperamide is a μ-opioid receptor agonist. [4] By binding to μ-opioid receptors, loperamide inhibits acetylcholine release and decreases excitation of neurons in the myenteric plexus, which leads to a decrease in peristalsis. [4] Decreasing intestinal motility prolongs the transit time of food content through the digestive tract, which allows for more fluid absorption; thereby alleviating diarrhea symptoms and improving stool consistency and frequency. [4]
Unlike other opiates, loperamide does not cross the blood brain barrier, so there is minimal risk for abuse. [5]
Side effects of use of anti-motility agents include:
Contraindications include:
CYP3A4 inhibitors, such as erythromycin, fluconazole, ketoconazole, quinidine, and ritonavir, increase plasma levels of loperamide. [7]
Bismuth subsalicylate (BSS) has both antibacterial and anti-secretory actions that help with diarrhea. [1] Once in the gut, BSS gets broken down into bismuth and salicylic acid. [1] Bismuth produces other bismuth salts, which blocks the binding and proliferation of bacteria in stomach mucosal cells, leading to a decrease in inflammation in the intestine. [9] Also, BSS inhibits cyclooxygenase enzyme and leads to a decrease in the production of prostaglandins, which are compounds that increase intestinal inflammation and motility. [1] Lastly, this antidiarrheal agent enhances fluid reabsorption, which helps improve diarrhea symptoms and stool consistency. [1]
Adverse effects include:
Contraindications include:
Drug interactions may occur with: [1]