Modern Management of Irritable Bowel Syndrome: More Than Motility

Abstract

In the treatment of irritable bowel syndrome (IBS), loperamide seems efficacious for diarrhea and ispaghula for constipation, while musculotropic spasmolytics may relieve abdominal pain. Antidepressants were found to be efficacious for abdominal pain, but their tolerance may be problematic and the therapeutic effect varied largely between trials. While meta-analyses suggest efficacy of probiotics as a group, the quality of the trials is often suboptimal and there is large variability. Lubiprostone, a chloride channel activator, and linaclotide, a guanylyl cyclase-C agonist, showed favorable effects on multiple symptoms in IBS with constipation. For IBS with diarrhea (IBS-D), the 5-HT3 receptor antagonist ramosetron showed efficacy in men and women, but is currently only approved in Japan. A multicenter study with the anti-emetic 5-HT3 receptor antagonist ondansetron showed efficacy on stool pattern in IBS-D. The poorly absorbable antibiotic rifaximin and eluxadoline, a mu opioid receptor agonist and delta antagonist, both showed efficacy in phase III trials in IBS-D and were approved by the FDA. Eluxadoline was associated with increased occurrence of sphincter of Oddi spasm and biliary pancreatitis. The non-pharmacological treatment of IBS, with dietary interventions (mainly gluten elimination and low FODMAP (fructose, oligo-, di-, monosaccharides and polyols)) has received a lot of attention lately. While responder rates vary across studies, perhaps based on regional variations in dietary intake of FODMAPs, the dietary approach seems to have acquired recognition as a valid therapeutic alternative. Long-term studies and comparative studies with pharmacotherapy, as well as elucidation of the underlying mechanisms of action, are needed.