Viberzi (eluxadoline) was approved by the FDA on May 27, 2015, for the treatment of IBS-D. Viberzi, like loperamide, activates mu-opioid receptors. In addition, Viberzi blocks delta-opioid receptors. When Viberzi 75 mg twice daily, 100 mg twice daily, or placebo were combined the response rates after 26 weeks were 29% in the 100 mg group, 23% in the 75 mg group, and 17% in the placebo group. Viberzi reduced abdominal pain and diarrhea. Its side effects include constipation, abdominal pain, and nausea.
IBS is associated with disruption of communication between the brain and the gut. Serotonin affects gut function and mood. In addition, 50 to 90% of patients seeking treatment for IBS have psychiatric conditions such as anxiety or depression and these conditions may worsen IBS symptoms. Tricyclic antidepressants (TCA) have been shown to improve diarrhea symptoms and abdominal pain. The evidence for selective serotonin reuptake inhibitor (SSRI) is less conclusive. Examples of TCAs used for treating IBS are amitriptyline 10 to 25 mg orally at bedtime, imipramine 25 to 50 mg orally at bedtime, and desipramine 50 mg three times daily.
Lotronex (alosetron) is a 5-HT3 antagonist effective for reducing abdominal pain and slowing gut motility. Common side effects include abdominal pain, nausea, and constipation. It may cause ischemic colitis and severe constipation that may result in hospitalization, surgery, and death. Alosetron was previously withdrawn in November 2000 for severe gastrointestinal events but was reinstated in June 2002 to treat severe IBS-D in women. It is only available through the Lotronex Risk Management Program. The recommended dose is 0.5 mg twice daily for 4 weeks.
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