Antimotility agents are drugs used to alleviate the symptoms of diarrhea. These include

loperamide Loperamide, sold under the brand name Imodium, among others,Drugs.co Page accessed 4 September 2015 is a medication of the opioid receptor agonist class used to decrease the frequency of diarrhea. It is often used for this purpose in irritable ...

(Imodium),

bismuth subsalicylate Bismuth subsalicylate, sold generically as pink bismuth and under brand names including Pepto-Bismol, Pepti-Calm, and BisBacter, is a medication used to treat temporary discomfort of the stomach and gastrointestinal tract. This includes an upset ...

(Pepto-Bismol),

diphenoxylate Diphenoxylate is a centrally active opioid drug of the phenylpiperidine series that is used as a combination drug with atropine for the treatment of diarrhea. Diphenoxylate is an opioid and acts by slowing intestinal contractions; the atropine ...

with

atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically give ...

(Lomotil), and

opiate An opiate is an alkaloid substance derived from opium (or poppy straw). It differs from the similar term ''opioid'' in that the latter is used to designate all substances, both natural and synthetic, that bind to opioid receptors in the brain ( ...

s such as paregoric, tincture of opium,

codeine Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is also commonly used as a recreational drug. It is found naturally in the sap of the opium poppy, ''Papaver somniferum''. It is typically use ...

, and

morphine Morphine, formerly also called morphia, is an opiate that is found naturally in opium, a dark brown resin produced by drying the latex of opium poppies (''Papaver somniferum''). It is mainly used as an analgesic (pain medication). There are ...

. In diarrhea caused by invasive pathogens such as ''

Salmonella ''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' ...

'', ''

Shigella ''Shigella'' is a genus of bacteria that is Gram negative, facultatively anaerobic, non–spore-forming, nonmotile, rod shaped, and is genetically nested within ''Escherichia''. The genus is named after Kiyoshi Shiga, who discovered it in 1 ...

'', and ''

Campylobacter ''Campylobacter'' is a type of bacteria that can cause a diarrheal disease in people. Its name means "curved bacteria", as the germ typically appears in a comma or "s" shape. According to its scientific classification, it is a genus of gram-negat ...

'', 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 ''Clostridioides difficile'' ( syn. ''Clostridium difficile'') is a bacterium known for causing serious diarrheal infections, and may also cause colon cancer. It is known also as ''C. difficile'', or ''C. diff'' (), and is a Gram-positive spec ...

'' cases. Use of antimotility agents in children and the elderly has also been discouraged in treatment of EHEC (

Shiga-like toxin Shiga toxins are a family of related toxins with two major groups, Stx1 and Stx2, expressed by genes considered to be part of the genome of lambdoid prophages. The toxins are named after Kiyoshi Shiga, who first described the bacterial orig ...

producing ''

Escherichia coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...

'') due to an increased rate of hemolytic uremic syndrome.

Loperamide (Imodium)

Mechanism of action

Loperamide is a μ-opioid receptor agonist. By binding to μ-opioid receptors, loperamide inhibits

acetylcholine Acetylcholine (ACh) is an organic compound that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Par ...

release and decreases excitation of neurons in the

myenteric plexus The myenteric plexus (or Auerbach's plexus) provides motor innervation to both layers of the muscular layer of the gut, having both parasympathetic and sympathetic input (although present ganglion cell bodies belong to parasympathetic innervatio ...

, which leads to a decrease in

peristalsis Peristalsis ( , ) is a type of intestinal motility, characterized by symmetry in biology#Radial symmetry, radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an wikt:anterograde, anterograde dir ...

. 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. Unlike other opiates, loperamide does not cross the blood brain barrier, so there is minimal risk for abuse.

Adverse effects

Side effects of use of anti-motility agents include: * Constipation * Abdominal cramps and discomfort * Nausea * Drowsiness * Dizziness * Dry mouth * Skin rash

Contraindications

Contraindications include: * Severe liver damage * Children 2 years old or younger * Malnourished individuals * Dehydrated individuals * Bloody diarrhea present

Drug interactions

CYP3A4 inhibitors, such as erythromycin, fluconazole, ketoconazole, quinidine, and ritonavir, increase plasma levels of loperamide.

Bismuth subsalicylate (Pepto-Bismol)

Mechanism of action

Bismuth subsalicylate (BSS) has both antibacterial and anti-secretory actions that help with diarrhea. Once in the gut, BSS gets broken down into bismuth and salicylic acid. 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. Also, BSS inhibits cyclooxygenase enzyme and leads to a decrease in the production of prostaglandins, which are compounds that increase intestinal inflammation and motility. Lastly, this antidiarrheal agent enhances fluid reabsorption, which helps improve diarrhea symptoms and stool consistency.

Adverse effects

Adverse effects include: * Black tongue * Dark/black stools * Tinnitus * Reye's syndrome in children

Contraindications

Contraindications include: * Pregnancy * Children with flu-like symptoms * Allergy to salicylates * Presence of gastrointestinal ulcers * Bleeding disorders (ie. hemophilia)

Drug interactions

Drug interactions may occur with: * Warfarin * Probenecid * Methotrexate * Medications containing high salicylate content

References

{{reflist Antidiarrhoeals

Loperamide (Imodium)

Mechanism of action

Adverse effects

Contraindications

Drug interactions

Bismuth subsalicylate (Pepto-Bismol)

Mechanism of action

Adverse effects

Contraindications

Drug interactions

See also

References