Irritable Bowel Syndrome: Newer Drugs Provide Relief

Irritable bowel syndrome (IBS) is a chronic, relapsing functional gastrointestinal (GI) disorder.^1-3 Patients who develop IBS report abdominal pain and altered bowel habits (Table 1)^1,4-6 with no identifiable cause. Patients may report a predominance of diarrhea (IBS-D) or constipation (IBS-C), but both may occur in an individual patient. Some patients report only abdominal pain and bloating (IBS-PB).¹ IBS prevalence (all types) is estimated at 10% to 20% of the US population and at any time, up to 2% of the population experiences active symptoms.^2,3 Women are up to 3 times more likely to develop IBS than men in the United States, and those with the condition are at increased risk of ectopic pregnancy and miscarriage.^4,5 Many adult patients report that they have experienced symptoms since childhood. Onset before 35 years of age is common.⁷

The etiology of IBS has not yet been identified. Examination of the large and small bowels has revealed altered GI motility. This delays meal transit in patients who report constipation but accelerates transport in patients who report diarrhea. Patients with IBS also have visceral hyperalgesia. Microscopically, some bacterial overgrowth and microscopic inflammation has been identified in patients who have IBS.⁸

In addition, IBS is associated with psychopathology. Patients with IBS tend to have a higher incidence of anxiety disorder, catastrophizing, major depression, panic disorder, and somatoform disorders than the general population.^1,9 A major concern in patients with IBS is suicidal attempts or ideation.¹⁰ Clinicians should heighten awareness around this risk.

IBS Management

Patients need to know 2 things: Symptoms tend to be chronic and exacerbate from time to time, and individuals need to avoid stressors and triggers.⁴ Patients with IBS need 3 types of support.

First, they need support to address the common psychological comorbidities. Cognitive behavioral therapy and judicious use of antidepressants may reduce symptoms or strengthen coping skills.^3,6,10

Second, they need advice about dietary measures that can ameliorate or prevent symptoms. Fiber supplementation can improve constipation and diarrhea, but it may cause bloating or distention. Clinicians should note that a Cochrane systematic review of bulking agents and fiber in IBS found that these medications had no benefit.¹¹ Regardless, many patients report improvement.

Third, additional dietary recommendations include staying adequately hydrated, limiting fermentable oligo-, di-, and monosaccharides and polyols, and supplementing calcium for patients who avoid lactose entirely.^12,13

Pharmacologic treatment is considered adjunct to lifestyle management and must be symptom directed.⁶ Clinicians can choose among anticholinergics, antidiarrheals, bulk-forming laxatives, chloride channel activators, guanylate cyclase C agonists, prokinetics, serotonin receptor antagonists, and tricyclic antidepressants. The choice of the drug(s) used depends on the patient’s symptoms, preference, and previous responses.⁶ The Figure shows the typical approach to treatment; note that the stepwise approach is deceptively simple, and no comparative effectiveness studies support its structure.⁶ For many patients, it will take time and trial and error to find the most successful strategy.¹⁴

In the past several years, the FDA has approved many agents to treat IBS. Table 2 describes the newer agents.^15-20

With recent developments, the likelihood of successful treatment for patients with any type of IBS is greater than ever before. Pharmacists need to take note of specific indications, the most common adverse reactions, and potential drug interactions. Given time and trial of multiple interventions, most patients will learn to live successfully with IBS and control its exacerbations.

Jeannette Y. Wick, RPh, MBA, FASCP, is assistant director of the Office of Pharmacy Professional Development at the University of Connecticut School of Pharmacy in Storrs.

References

• Definition and facts for irritable bowel syndrome. National Institute of Diabetes and Digestive and Kidney Diseases website. niddk.nih.gov/health-information/digestive-diseases/irritable-bowel-syndrome/definition-facts. Published November 2017. Accessed April 2, 2017.
• Buono JL, Carson RT, Flores NM. Health-related quality of life, work productivity, and indirect costs among patients with irritable bowel syndrome with diarrhea. Health Qual Life Outcomes. 2017;15(1):35. doi: 10.1186/s12955-017-0611-2.
• Ballou S, Keefer L. The impact of irritable bowel syndrome on daily functioning: characterizing and understanding daily consequences of IBS. Neurogastroenterol Motil. 2017;29(4). doi: 10.1111/nmo.12982.
• Khashan AS, Quigley EM, McNamee R, McCarthy FP, Shanahan F, Kenny LC. Increased risk of miscarriage and ectopic pregnancy among women with irritable bowel syndrome. Clin Gastroenterol Hepatol. 2012;10(8):902-909. doi: 10.1016/j.cgh.2012.02.014.
• Weinberg DS, Smalley W, Heidelbaugh JJ, Sultan S; American Gastroenterological Association. American Gastroenterological Association Institute Guideline on the pharmacological management of irritable bowel syndrome. Gastroenterology. 2014;147(5):1146-1148. doi: 10.1053/j.gastro.2014.09.001.
• Houghton LA, Lea R, Agrawal A, Reilly B, Whorwell PJ. Relationship of abdominal bloating to distention in irritable bowel syndrome and effect of bowel habit. Gastroenterology. 2006;131(4):1003-1010. doi: 10.1053/j.gastro.2006.07.015.
• Chumpitazi BP, Weidler EM, Lu DY, Tsai CM, Shulman RJ. Self-perceived food intolerances are common and associated with clinical severity in childhood irritable bowel syndrome. J Acad Nutr Diet. 2016;116(9):1458-1464. doi: 10.1016/j.jand.2016.04.017.
• Symptoms and causes of irritable bowel syndrome. National Institute of Diabetes and Digestive and Kidney Diseases website. niddk.nih.gov/health-information/digestive-diseases/irritable-bowel-syndrome/symptoms-causes. Published November 2017. Accessed April 2, 2017.
• Sherwin LB, Leary E, Henderson WA. The association of catastrophizing with quality-of-life outcomes in patients with irritable bowel syndrome. Qual Life Res. 26(8):2161-2170. doi: 10.1007/s11136-017-1554-0.
• Ballou S, Bedell A, Keefer L. Psychosocial impact of irritable bowel syndrome: a brief review. World J Gastrointest Pathophysiol. 2015;6(4):120-123. doi: 10.4291/wjgp.v6.i4.120.
• Ruepert L, Quartero AO, de Wit NJ, van der Heijden GJ, Rubin G, Muris JW. Bulking agents, antispasmodics and antidepressants for the treatment of irritable bowel syndrome. Cochrane Database Syst Rev. 2011;(8):CD003460. doi: 10.1002/14651858.CD003460.pub3.
• Gibson PR. Use of the low-FODMAP diet in inflammatory bowel disease. J Gastroenterol Hepatol. 2017;32(suppl 1):40-42. doi: 10.1111/jgh.13695.
• Miheller P, Gesztes W, Lakatos PL. Manipulating bone disease in inflammatory bowel disease patients. Ann Gastroenterol. 2013;26(4):296-303.
• Kuritzky L. Hot topics in primary care: individualizing pharmacologic management of irritable bowel syndrome. J Fam Pract. 2015;64(suppl 12):S16-S21.
• Xifaxan [prescribing information]. Bridgewater, NJ: Salix Pharmaceuticals Inc; 2004. www.accessdata.fda.gov/drugsatfda_docs/label/2010/022554lbl.pdf. Accessed May 25, 2018.
• Viberzi [prescribing information]. Madison, NJ: Allergan USA Inc; 2018. allergan.com/assets/pdf/viberzi_pi. Accessed May 25, 2018.
• Linzess [prescribing information]. Irvine, CA: Allergan USA Inc; 2017. allergan.com/assets/pdf/linzess_pi. Accessed May 25, 2018.
• Amitiza [prescribing information]. Deerfield, IL: Takeda Pharmaceuticals America Inc; 2006. general.takedapharm.com/amitizapi. Accessed May 25, 2018.
• Lotronex [prescribing information]. Roswell, GA: Sebela Pharmaceuticals Inc; 2016. lotronex.com/hcp/. Accessed May 25, 2018.
• Zheng Y, Yu T, Tang Y, et al. Efficacy and safety of 5-hydroxytryptamine 3 receptor antagonists in irritable bowel syndrome: a systematic review and meta-analysis of randomized controlled trials. PLoS One. 2017;12(3):e0172846. doi: 10.1371/journal.pone.0172846.