New and Emerging Treatment Options for Irritable Bowel Syndrome

Abstract

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder associated with abdominal pain, diarrhea, constipation, or a mix of symptoms. The pathophysiology of IBS is not completely understood but appears to involve genetics, the gut microbiome, immune activation, altered intestinal permeability, and brain-gut interactions. There is no gold standard for diagnosis. Several sets of symptom-based guidelines exist. Treatment strategies for IBS may include both nonpharmacologic and pharmacologic approaches. Lifestyle modifications that aim to improve exercise, sleep, diet, and stress may be warranted. Recent data suggest that a gluten-free diet and a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) may benefit some patients. For patients with diarrhea-predominant IBS, treatment options include the synthetic peripheral μ-opioid receptor agonist loperamide, antispasmodic agents, antidepressants, serotonin 5-HT3 antagonists, and the gut-specific antibiotic rifaximin. Ongoing research is evaluating the use of probiotics. For patients with constipation-predominant IBS, therapeutic strategies may include dietary fiber, laxatives, and the prosecretory agents lubiprostone and linaclotide. Research is continuing to optimize the use of available agents and evaluating new approaches to further improve the care of patients with IBS.

Figure 1

Worldwide prevalence of irritable bowel syndrome.

Figure 2

Long-term dietary changes can alter the gut microbiome.

Figure 3

Impact of irritable bowel syndrome on various aspects of life, as reported in a survey of 261 patients.

Figure 4

Frequency of BMs in patients randomized to a diet with or without gluten. BM, bowel movement; BSFS, Bristol Stool Form Scale; GCD, gluten-containing diet; GFD, gluten-free diet.

Figure 5

Time course for stool consistency during treatment periods in a randomized, double-blind, crossover study of ondansetron.

Figure 6

Patients with adequate relief of global IBS symptoms in TARGET 1 and TARGET 2 during the 10-week follow-up period after cessation of treatment with rifaximin or placebo. IBS, irritable bowel syndrome.

Figure 7

Overall response in patients with IBS-C in 2 randomized, placebo-controlled trials comparing lubiprostone vs placebo. IBS-C, irritable bowel syndrome with constipation.