Digesting the details of IBS

CaseHT, a 28-year-old female, seeks your advice on managing her gastrointestinal (GI) symptoms. For the past six months, she has experienced abdominal pain alongside alternating episodes of diarrhea and constipation, bloating, flatulence and occasional belching. Her symptoms are often triggered by emotional stress, anxiety, and certain foods such as dairy, fruits and high-fat meals. HT has a history of migraines, which she manages with sumatriptan. She has no known allergies. HT has tried over-the-counter remedies for her GI symptoms, including stimulant laxatives and antidiarrheal agents, but these have provided only minimal relief. She does not drink alcohol, smoke or use recreational drugs and has no family history of GI disorders or colorectal cancer. HT mentions that she often cannot participate in work or social activities outside her home unless there are easily accessible bathroom facilities available.BackgroundIrritable bowel syndrome (IBS) is a chronic functional GI disorder characterized by recurrent abdominal pain and altered bowel habits (i.e., constipation, diarrhea, or both), often accompanied by abdominal bloating, and occurring without any identifiable organic cause.1 It is one of the most common GI disorders, affecting approximately 10% of the general population.1 IBS significantly impacts patients’ quality of life and is associated with considerable healthcare resource utilization.2The exact etiology of IBS remains unclear, but is believed to involve a combination of abnormal GI motility, visceral hypersensitivity, altered gut-brain interactions and gut microbiota changes.3,4 Psychological factors, such as chronic stress and anxiety, can exacerbate symptoms.3,4When assessing and diagnosing IBS, a full history and relevant examination are recommended, with limited use of diagnostic tests (see Table 1). The current recommended diagnostic criteria for IBS are the Rome IV criteria: abdominal pain (≥ 1 day/week for ≥ 3 months) associated with defecation or a change in bowel habits.1 Pain can occur anywhere in the abdomen, but it is more commonly experienced in the lower abdomen.4,5 IBS is then subtyped based on predominant symptoms (Figure 1): constipation-predominant (IBS-C, > 25% hard stools and 25% loose stools and 25% loose stools and > 25% hard stools); and unclassified (IBS-U < 25% loose stools and < 25% hard stools).1The Bristol Stool Form Scale (BSFS) is a valuable tool for evaluating bowel habits (Figure 1).1 It has been demonstrated to be a reliable surrogate marker for colonic transit. To help guide treatment, IBS subtypes should be determined according to stool consistency using the BSFS. Subtyping is more accurate when patients experience at least four days of abnormal bowel habits per month. Subtypes should be based on the BSFS for days with abnormal bowel habits. Most patients with IBS have chronic symptoms that vary in severity over time. Patients may also experience a change in IBS subtype over time with the most frequent change being from predominant constipation or diarrhea to mixed bowel habits.5IBS patients often report that meals trigger or worsen their symptoms, although these symptoms are not specific enough to be included in the IBS diagnostic criteria.4 Additionally, a variety of other GI symptoms (e.g., dyspepsia) and non-GI symptoms (e.g., migraine headaches, fibromyalgia, interstitial cystitis, dyspareunia) are frequently present in IBS patients. The presence of these concurrent symptoms further supports the diagnosis of IBS.General treatment approachAdditional testing for IBS is typically guided by the presence of alarm features. Although these features suggest a higher likelihood of organic disease, the results of such tests are usually negative or inconclusive.3,5 Alarm features include abdominal mass, onset of symptoms after age 50, rectal bleeding or melena, nocturnal diarrhea, progressive abdominal pain, unexplained weight loss, laboratory abnormalities (e.g., iron deficiency anemia, elevated C-reactive protein), and a family history of inflammatory bowel disease or colorectal cancer.1,3,5,6In the absence of alarm signs and symptoms, routine diagnostic tests for IBS can be minimized, especially for patients under 50, who have a low probability of an alternate organic disease.3 Specific tests should be based on individual symptoms and clinical suspicion (Table 1). Referral to a gastroenterologist is recommended if alarm features are present or if management strategies prove ineffective.Effective management of IBS involves a combination of dietary modifications, lifestyle changes, and pharmacologic treatments tailored to the patient’s symptoms and subtype. Pharmacists are well-positioned to provide patient education, recommend appropriate OTC products, and collaborate with other healthcare providers for optimal care. A stepwise management approach, incorporating both nonpharmacologic and pharmacologic therapies, is usually advocated, with nonpharmacologic interventions being sufficient for some patients. However, those with moderate to severe symptoms often require pharmacologic treatments.Nonpharmacologic interventionsIBS is highly variable, with different triggers for each person. Dietary modifications are often the first line of treatment. Keeping a food intake and symptom diary helps identify and avoid problematic foods, such as high-fat foods, caffeine, alcohol and artificial sweeteners. The low FODMAP diet, which restricts fermentable oligosaccharides, disaccharides, monosaccharides and polyols, has been shown to improve symptoms in many IBS patients.7,8 This diet involves avoiding specific foods for six to eight weeks to see if symptoms subside. If symptoms improve, FODMAPs can be slowly reintroduced to a tolerable limit. Since many foods contain FODMAPs, long-term removal can increase the risk of nutritional deficiencies. Therefore, patients should consult a registered dietitian before eliminating any food group long-term.Figure 2 summarizes dietary modifications and adjunctive pharmacologic therapies (peppermint oil, antispasmodics, probiotics) for IBS.1,6 Stress management techniques and other psychological therapies can also be beneficial in reducing symptom severity.1Pharmacologic treatmentsInitial treatment of any IBS subtype may include a trial of psyllium to help reduce symptoms. Patients whose main symptoms include pain or bloating may benefit from peppermint oil or antispasmodics. Additional pharmacologic treatments should be individualized based on the patient’s predominant symptoms and the severity of their condition (see Figure 3).1-31. For IBS-C:Fibre supplements (e.g., psyllium) can help improve bowel regularity, but insoluble fibre (e.g., wheat bran) may worsen symptoms.1-5Osmotic laxatives (e.g., polyethylene glycol) can be used for short-term relief of constipation, but will not help abdominal pain.Linaclotide 290 µg daily, a prescription medication, can be used first- line in patients along with lifestyle changes to improve pain and increase the number of bowel movements.1Selective serotonin reuptake inhibitors (e.g., citalopram) may decrease transit time and can help manage IBS symptoms in patients with comorbid depression.Lubiprostone 8 µg twice daily, a prescription medication, can be considered for patients with moderate to severe IBS-C who do not respond to first-line treatments.2. For IBS-D:Antidiarrheal agents (e.g., loperamide) can be used prophylactically when patients anticipate diarrhea; they can reduce stool frequency, but do not relieve abdominal pain.Low-dose tricyclic antidepressants (e.g., nortriptyline, desipramine) can help manage pain and improve overall symptoms.Eluxadoline 100 mg twice daily, a newer prescription option with mixed opioid effects, provides relief from both diarrhea and abdominal pain.3. For IBS-M or IBS-U:Treatment should be symptom-directed, addressing constipation and diarrhea as they occur.Low-dose tricyclic antidepressants (e.g., nortriptyline, desipramine) can help manage pain and improve overall symptoms.Case analysisHT presents with symptoms consistent with IBS-M, characterized by alternating episodes of diarrhea and constipation, along with abdominal pain and bloating. Given her history of stress and anxiety, psychological interventions (e.g., cognitive behavioural therapy [CBT] or hypnotherapy) should be a key component of her treatment plan.Case recommendation1. Dietary and lifestyle modifications:Advise HT to maintain a food and symptom diary to identify potential IBS triggers.Recommend a low FODMAP diet, implemented under the guidance of a dietician, for as short-term as possible (e.g., 4 weeks) to reduce symptoms.Encourage CBT.Let HT know that reducing air intake, the main source of intestinal gas, and avoiding gas-producing foods in large amounts can help reduce flatulence and belching. To minimize swallowed air, avoid chewing gum, gulping food, carbonated drinks, washing food down with liquids, and sipping hot drinks. Chronic anxiety and tension can also increase air swallowing.2. Pharmacologic treatment:Recommend 25 g of fibre daily (legumes, grains such as oatmeal, vegetables).Consider soluble fibre supplements (e.g., psyllium) in patients who cannot meet their daily fibre intake target to improve bowel regularity. Advise HT to take up to 12 g per day, gradually increasing by 3 g/day every week to avoid bloating and flatulence. Encourage increased fluid intake simultaneously.Probiotics, especially combination products containing various Lactobacillus species, have shown efficacy in improving IBS symptoms; single-species Lactobacillus products show less significant benefits.1 Despite potential benefits, the effectiveness of specific probiotic strains is unclear, and patients should opt for licensed products due to regulation and shelf-life concerns. Products with Health Canada-approved indications for IBS, along with their dosage forms and doses, can be easily found using the probioticchart.ca tool.9 A one-month probiotic trial is recommended, considering the economic burden and the appeal of probiotics as a natural, low-risk option.Suggest peppermint oil 180 mg tid, in an encapsulated form to reduce its potential adverse effects of heartburn and nausea.1,10Consider an antispasmodic (e.g., dicyclomine 10 mg tid-qid) “as-needed” to relieve abdominal pain.If symptoms persist or significantly impact her quality of life, discuss the option of referral to a gastroenterologist via her primary care provider for further evaluation and potential prescription treatments.3. Follow-up:Schedule a follow-up appointment with HT in four to six weeks to assess symptom improvement and adherence to dietary and lifestyle recommendations, as well as to reassess the effectiveness of pharmacologic treatments and make adjustments as necessary.SummaryBy providing comprehensive management tailored to a patient’s specific symptoms and needs, pharmacists can play a crucial role in improving the quality of life for patients with IBS. With a good understanding and consistent adherence to an individualized treatment plan, many patients with IBS, like HT, can expect significant improvement over time. Statistics show that about 10% of IBS patients improve each year.8Dr. Nardine Nakhla is a practising community pharmacist and a faculty member at the University of Waterloo School of Pharmacy.References:Moayyedi P, Andrews CN, MacQueen G, et al. Canadian Association of Gastroenterology clinical practice guideline for the management of irritable bowel syndrome (IBS). J Can Assoc Gastroenterol 2019;2(1):6-29. doi:10.1093/jcag/gwy071.Canavan C, West J, Card T. Review article: the economic impact of the irritable bowel syndrome. Aliment Pharmacol Ther 2014;40:1023-34.Pinto-Sanchez MI, Bercik P. Irritable bowel syndrome. In: Compendium of Therapeutics Choices. Canadian Pharmacists Association. Updated May 13, 2021. Accessed June 1, 2024.Mearin F, Lacy BE, Chang L, et al. Bowel disorders. Gastroenterology 2016;150:1393–407.e5. doi:10.1053/j.gastro.2016.02.031.Wald A. Clinical manifestations and diagnosis of irritable bowel syndrome in adults. In: Post T, ed. UpToDate 2024. (accessed February 27, 2024).Wald A. Treatment of irritable bowel syndrome in adults. In: Post T, ed. UpToDate 2024. (accessed June 24, 2024).Dean G, Chey SW, Singh P, et al. A diet low in fermentable oligo-, di-, monosaccharides and polyols improves abdominal and overall symptoms in persons with all subtypes of irritable bowel syndrome. 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