IBS Management Often Requires Dietary Changes, Education, and Medication

Irritable bowel syndrome (IBS) is a common chronic functional gastrointestinal disorder characterized by recurrent abdominal discomfort and altered bowel habits that affects 10% to 15% of adults in the United States.¹

IBS is also associated with increased economic burden and work absenteeism, and it can negatively affect quality of life including daily living and interpersonal relationships.²

The clinical manifestations of IBS are recurrent abdominal pain with variable characteristics often associated with bloating and relieved by defecation. Patients with IBS have recurrent altered bowel habits described as a change in stool characteristics and frequency. IBS is further classified as constipation predominant subtypes, IBS with mixed bowel habits, or IBS with predominant diarrhea. IBS is usually diagnosed based on a thorough medical history. Laboratory and other diagnostic tests may be used to exclude other diagnoses particularly in the presence of features, such as blood in the stool, a family history of colon cancer or inflammatory bowel disease, nocturnal diarrhea, onset after aged 50 years of age, and weight loss.3

IBS is more common in individuals younger than aged 50 years and women. IBS is associated with an increase in certain psychological comorbidities, including major anxiety, depression, and somatization.⁴ IBS is also more commonly associated with other disorders, including fibromyalgia and gastroesophageal reflux functional dyspepsia.⁵

Treatment Options for IBS

Management of IBS is multidimensional, and it includes dietary and lifestyle modifications and in certain cases pharmacologic therapy. Dietary modifications include an exclusion or reduction in gas-producing foods, such as beans, certain fruits and vegetables, lentils, wheat germ and whole grains. A diet low in fermentable oligo-, di-, and monosaccharides and polyols, including food apples, certain vegetables, dairy products, legumes, peaches, pears, and whole grains, may improve IBS symptoms.⁶ Physical activity is also associated with improvement of IBS symptoms and should be encouraged for overall health.

Pharmacologic Therapy

Pharmacologic therapy for IBS is considered in patients with moderate to severe symptoms and those who do not respond to dietary and lifestyle changes. Pharmacotherapy is tailored to main the predominant IBS symptoms, such as constipation and diarrhea. For patients with IBS with constipation (IBS-C) a stepwise approach can begin with an increase in soluble fiber, such as isphagula/psyllium. The next treatment step is polyethylene glycol (PEG) taken daily at a dose of 17 to 34 g mixed with water. For patients with IBS with persistent constipation despite PEG there are specific prescription pharmacologic options including:

• Lubiprostone is the next step if PEG is not effective. Lubiprostone is approved for adult women with IBS-C, and it is administered 8 micrograms twice daily orally with food. Nausea is the most common adverse effect (AE) of lubiprostone. Constipation is usually improved by 1 to 2 weeks after starting lubiprostone.⁷
• Linaclotide and plebanates are other options for IBS- C with persistent constipation. Linaclotide is administered 290 micrograms orally once daily, and diarrhea is the most common adverse effect. Constipation is usually improved by 1 week after starting linaclotide.⁸ Plebanates is dosed 3 mg once daily, and it has similar efficacy and tolerability to linaclotide. Plecanatide can also reduce IBS-related abdominal pain. Plecanatide may relieve constipation after 24 hours.⁹ Linaclotide and plecanatide are contraindicated in children, because of the potential for severe dehydration.
• Tenapanor is the newest medication for IBS- C, and it is administered 50 mg twice daily. Tenapanor also improves abdominal bloating and pain. The most common AE of tenapanor is diarrhea.¹⁰

Prescription IBS-C medications can be costly. Lubiprostone is available in brand and generic capsules, and it is the least expensive prescription IBS-C medication. Linaclotide and plecanatide are brand-only and have a similar cost per dose. Tenapanor is brand only and is the most expensive IBS-C medication per dose.¹¹

There are a few pharmacologic treatment options for patients with IBS with predominant diarrhea symptoms (IBS-D). Loperamide 2 mg before meals is an antidiarrheal agent used for initial treatment of IBS-D. Second-line options include eluxadoline 100 mg twice daily, which is expensive and contraindicated in patients with a history of gallbladder, pancreatitis, or severe liver disease. Patients with severe IBS-D that is refractory to other treatments may try bile acid sequestrants, such as alosetron or colesevalam. Alosetron is restricted to patients with chronic, refractory, severe IBS-D, and it has certain prescribing restrictions, because of risk of severe constipation and ischemic colitis.¹²

Abdominal bloating and pain are core features of IBS and may be treated with antispasmodics as needed. Antispasmodics, such as dicyclomine or hyoscyamine, are anticholinergic agents and provide short-term relief of abdominal cramps and pain but can increase constipation.³ The antibiotic rifaximin 550 mg 3 times daily or a placebo for a total of 14 days may be used for severe IBS with abdominal bloating and pain.

Conclusion

IBS management requires a combination of patient dietary modification and education and may require pharmacologic therapy. The pharmacologic options for IBS are based on the predominant IBS AE profile, cost, and symptoms.

References

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2. Ballou S, McMahon C, Lee HN, et al. Effects of irritable bowel syndrome on daily activities vary among subtypes based on results from the IBS in America survey. Clin Gastroenterol Hepatol. 2019;17(12):2471-2478.e3. doi:10.1016/j.cgh.2019.08.016

3. American College of Gastroenterology Task Force on Irritable Bowel Syndrome, Brandt LJ, Chey WD, et al. An evidence-based position statement on the management of irritable bowel syndrome. Am J Gastroenterol. 2009;104 Suppl 1:S1. doi:10.1038/ajg.2008.122

4. Solmaz M, Kavuk I, Sayar K. Psychological factors in the irritable bowel syndrome. Eur J Med Res. 2003;8(12):5490556.

5. Chey WD, Kurlander J, Eswaran S. Irritable bowel syndrome: a clinical review. JAMA. 2015;313(9):949-958. doi:10.1001/jama.2015.0954

6. Shepherd SJ, Lomer MC, Gibson PR. Short-chain carbohydrates and functional gastrointestinal disorders. Am J Gastroenterol. 2013;108(5):707717. doi:10.1038/ajg.2013.96

7. Amitiza (lubiprostone). Prescribing information. Takeda Pharmaceuticals America, Inc; 2012. Accessed October 5, 2022. https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/021908s010lbl.pdf

8. Linzess (linaclotide). Prescribing information. Allergan USA, Inc. 2017. Accessed October 5, 2022. https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/202811s013lbl.pdf

9. Trulance (plecanatide). Prescribing information. Synergy Pharmaceuticals, Inc. 2017. Accessed October 5, 2022. https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/208745lbl.pdf

10. Ibsrela (tenapanor). Prescribing information. Ardelyx, Inc. 2019. Accessed October 5, 2022. https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/211801s000lbl.pdf

11. Ibsrela prices, coupons and patient assistance programs. Drugs.com. Accessed October 5, 2022. https://www.drugs.com/price-guide/ibsrela

12. Lotronex (alosetron). Prescribing information. Prometheus Laboratories, Inc. 2008. https://www.accessdata.fda.gov/drugsatfda_docs/label/2008/021107s013lbl.pdf