Antidiarrheal agents include bulk forming agents, hydroscopic agents, bile acid resins, bismuth, inhibitors of intestinal motility, non-absorbed antibiotics and hormones. Bulk forming agents include methylcellulose; hydroscopic agents include pectin and kaolin; bile acid resins are cholestyramine, colestipol and colesevalam; inhibitors of intestinal motility include opioids such as diphenoxylate and loperamide. Antibiotics include rifamycin and rifaximin which are non-absorbed and are used for travelers' diarrhea. Hormones with antidiarrheal activity include octretide and somatostatin. Most antidiarrheal agents are active locally in the small intestine and colon and are largely not absorbed. Some, however, have been implicated in rare causes of liver injury (senna, cascara, cholestyramine). Telotristat is a relatively new agent that inhibits the synthesis of serotonin and is used specifically for the diarrhea of carcinoid syndrome.
Antiemetics are a diverse group of medications that act at different points in the pathways that regulate nausea and vomiting. These include antihistamines, anticholinergic agents, phenothiazines, serotonin type 3 receptor blockers, centrally acting benzamides, cannabinoid receptor agonists, substance P antagonists and miscellaneous.
Cannabinoid Receptor Agonists
- Dronabinol, Nabilone, Tetrahydrocannabinol
- Phenothiazines [See Antipsychotic Agents]
- Chlorpromazine, Prochlorperazine
Substance P/Neurokinin 1 Receptor Antagonists
Acid peptic disease/antiulcer agents that include antacids, the histamine type 2 receptor blockers (H2 blockers), and the proton pump inhibitors (PPIs). These agents are some of the most commonly taken medications and are very well tolerated, most being available both by prescription and over-the-counter. While many of these drugs are approved for use in duodenal and gastric ulcer disease, their major use is for acid reflux and indigestion.
Cathartics, laxatives or agents for constipation include bulk forming agents, osmotic agents, stool wetting agents, nonspecific stimulants, prokinetic agents and agents that increase fluid secretion. Many of these therapies are not systemically absorbed and none are considered particularly hepatotoxic. Naldemedine and naloxegol are opioid antagonists and are used to treat the constipation associated with opioid use.
- Cascara Sagrada
- Castor Oil
- Fiber, Bran
- Magnesium Sulfate
- Naldemedine (Opioid Antagonist)
- Naloxegol (Opioid Antagonist)
- Plecanatide (for Chronic Idiopathic Constipation)
- Prucalopride (for Chronic Idiopathic Constipation)
Inflammatory bowel disease encompasses several disorders, most commonly ulcerative colitis and Crohn colitis. Agents can be classified as 5-aminosalicyclic acid (5-ASA) based agents, immunosuppressive drugs, antitumor necrosis factor agents, corticosteroids, antibiotics and miscellaneous.
5-Aminosalicyclic Acid (5-ASA) Derivatives
Tumor Necrosis Factor Antagonists
Irritable Bowel Syndrome Agents Antimuscarinics/Antispasmodics [See Anticholinergic agents