Managing IBS often requires dietary changes, education, and medications

Pharmacological options for irritable bowel syndrome are based on adverse effect profile, cost, and predominant symptoms.

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 of varying characteristics often associated with bloating and relieved by defecation. Patients with IBS have recurrent altered bowel habits described as a change in stool patterns and frequency. IBS is further categorized into constipation predominant subtypes, IBS with mixed bowel habits or IBS with diarrhea predominant. IBS is usually diagnosed based on a thorough medical history. Laboratory tests and other diagnostic tests may be used to rule out other diagnoses, especially if features such as blood in the stool, family history of colon cancer or inflammatory bowel disease are present. , nocturnal diarrhea, onset after age 50, and weight. loss.3

IBS is more common in people under 50 and in women. IBS is associated with an increase in certain psychological comorbidities, including major anxiety, depression, and somatization.4 IBS is also more often associated with other disorders, including fibromyalgia and functional dyspepsia from gastroesophageal reflux disease.5

Treatment options for IBS

The management of IBS is multifaceted and includes dietary and lifestyle modifications and, in some cases, pharmacological therapy. Dietary modifications include an exclusion or reduction of 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 edible apples, certain vegetables, dairy products, legumes, peaches, pears, and whole grains, may improve IBS symptoms.6 Physical activity is also associated with improving IBS symptoms and should be encouraged for overall health.

Pharmacological therapy

Pharmacological treatment of IBS is considered in patients with moderate to severe symptoms and in those unresponsive to diet and lifestyle changes. Drug therapy is tailored to the main predominant symptoms of IBS, such as constipation and diarrhea. For patients with IBS with Constipation (IBS-C), a stepwise approach can start with increasing soluble fiber, such as isphagula/psyllium. The next stage of treatment is polyethylene glycol (PEG) taken daily at a dose of 17-34 g mixed with water. For IBS patients with persistent constipation despite PEG, there are specific prescription pharmacological options, including:

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

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

There are a few pharmacological treatment options for patients with IBS with diarrhea-predominant symptoms (IBS-D). Loperamide 2 mg before meals is an antidiarrheal agent used for the 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 refractory to other treatments can try bile acid sequestrants, such as alosetron or colesevalam. Alosetron is reserved for patients with chronic, refractory and severe IBS-D, and it has certain prescribing restrictions, due to the risk of severe constipation and ischemic colitis.12

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

Conclusion

Management of IBS requires a combination of dietary modifications and patient education and may require pharmacological treatment. Pharmacological options for IBS are based on the profile, cost, and predominant symptoms of IBS AEs.

References

1. Everhart JE, Ruhl CE. Burden of Digestive Diseases in the United States, Part II: Lower Gastrointestinal Diseases. Gastroenterology. 2009;136(3):741-754. doi:10.1053/j.gastro.2009.01.015

2. Ballou S, McMahon C, Lee HN, et al. The effects of irritable bowel syndrome on daily activities vary by subtype 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 Supplement 1:S1. doi:10.1038/ajg.2008.122

4. Solmaz M, Kavuk I, Sayar K. Psychological factors in 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 (plecanatid). 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

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