Aprepitant

aprepitant (uh-PREH-pih-tunt) is a drug used with other drugs to prevent nausea and vomiting caused by chemotherapy. It is also used to prevent nausea and vomiting after surgery. Aprepitant blocks the action of a certain chemical in the brain that may trigger nausea and vomiting. Blocking this chemical may lessen nausea and vomiting. Aprepitant is a type of antiemetic and a type of substance P/neurokinin 1 receptor antagonist. Also called Emend.

Information about Aprepitant

Aprepitant is an orally available antiemetic agent that is used to prevent postoperative or cancer chemotherapy related nausea and vomiting. 

Liver safety of Aprepitant

Aprepitant is associated with a low rate of serum enzyme elevations during therapy, but has not been clearly linked to cases of clinically apparent liver injury with jaundice.

Mechanism of action of Aprepitant

Aprepitant (a pre’ pi tant) is a complex molecule with a central morpholine core and two ring carbons and fluorinated phenyl groups.  Aprepitant acts as a substance P antagonist blocking the neurokinin 1 (NK1) receptor, which is found in the central nervous system and induces the vomiting reflex when activated by substance P.  Aprepitant has been shown to inhibit both acute and delayed nausea and vomiting associated with cancer chemotherapy and surgical procedures.  It appears to act synergistically with serotonin type 3 (5-HT3) receptor blockers. 

{fda}} Aprepitant was approved for use in the United States in 2003 and current indications include prevention of postoperative and chemotherapy associated nausea and vomiting. 

Dosage and administration for Aprepitant

Aprepitant is available as 40, 80 and 125 mg capsules under the brand name Emend.  The typical adult oral dose for postoperative nausea and vomiting is 40 mg within four hours of anesthesia induction.  The dose for preventing nausea and vomiting due to chemotherapy is usually 125 mg one hour before chemotherapy given in combination with dexamethasone and a 5-HT3 receptor blocker, followed by 80 mg of aprepitant and dexamethasone orally on days 2 and 3.  Fosaprepitant is a prodrug of aprepitant and is available as a solution for injection in single use vials of 115 and 150 mg. 

Side effects of Aprepitant

Common side effects of oral aprepitant include fatigue, drowsiness, dizziness, headache, diarrhea and abdominal discomfort.

Antidiarrheal agents

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.

• Cholestyramine
• Colesevelam
• Colestipol
• Crofelemer
• Difenoxin
• Diphenoxylate
• Kaolin
• Loperamide
• Methylcellulose
• Octreotide
• Pectin
• Rifamycin
• Rifaximin
• Somatostatin
• Telotristat

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.

Anticholinergic Agents

• Hyoscyamine, Methscopolamine, Scopolamine

Antihistamines

• Cyclizine, Dimenhydrinate, Hydroxyzine, Meclizine, and Promethazine

Cannabinoid Receptor Agonists

• Dronabinol, Nabilone, Tetrahydrocannabinol
• Phenothiazines [See Antipsychotic Agents]
• Chlorpromazine, Prochlorperazine

Serotonin 5-HT3 Receptor Antagonists

• Alosetron, Dolasetron, Granisetron, Ondansetron, Palonosetron

Substance P/Neurokinin 1 Receptor Antagonists

• Aprepitant, Fosaprepitant, Rolapitant

Miscellaneous

• Dexamethasone, Metoclopramide, Trimethobenzamide

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.

Histamine H2 Receptor Antagonists (H2 Blockers) Cimetidine, Famotidine, Nizatidine, Ranitidine

Proton Pump Inhibitors

• Dexlansoprazole, Esomeprazole, Lansoprazole, Omeprazole, Pantoprazole, Rabeprazole

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.

• Bisacodyl
• Cascara Sagrada
• Castor Oil
• Docusate
• Fiber, Bran
• Lactulose
• Magnesium Sulfate
• Methylcellulose
• Naldemedine (Opioid Antagonist)
• Naloxegol (Opioid Antagonist)
• Plecanatide (for Chronic Idiopathic Constipation)
• Prucalopride (for Chronic Idiopathic Constipation)
• Senna

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

• Balsalazide, Mesalamine, Olsalazine, Sulfasalazine

Immunosuppressive Agents

• Azathioprine, Mercaptopurine, Methotrexate

Tumor Necrosis Factor Antagonists

• Adalimumab, Certolizumab, Golimumab, Infliximab

Miscellaneous

• Metronidazole, Natalizumab, Vedolizumab

Irritable Bowel Syndrome Agents Antimuscarinics/Antispasmodics [See Anticholinergic agents

• Dicyclomine, Glycopyrrolate, Hyoscyamine, Methscopolamine

Prokinetic Agents - See Serotonin 5-ht4 receptor agonists Alosetron, Cisapride, Domperidone, Linaclotide, Lubiprostone, Metoclopramide, Plecanatide, Prucalopride, Tegaserod

Other

• Eluxadoline

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