What are the treatment options for Irritable Bowel Syndrome with Diarrhea (IBS-D)?

Treatment Options for Irritable Bowel Syndrome with Diarrhea (IBS-D)

For patients with IBS-D, a structured approach starting with first-line dietary and lifestyle modifications followed by pharmacological interventions targeting predominant symptoms offers the most effective management strategy, with 5-HT3 receptor antagonists being the most efficacious drug class for IBS-D. 1

First-Line Treatments

Lifestyle Modifications

• Regular exercise should be advised for all patients with IBS-D as it can improve symptoms 1
• First-line dietary advice should be offered to all patients 1

Dietary Approaches

• Soluble fiber (e.g., ispaghula) is effective for global symptoms and abdominal pain, starting at low doses (3-4g/day) and gradually increasing to avoid bloating 1
• Low FODMAP diet can be considered as second-line dietary therapy, but should be supervised by a trained dietitian with planned reintroduction of FODMAPs according to tolerance 1
• Food elimination diets based on IgG antibodies are not recommended 1
• Gluten-free diets are not recommended specifically for IBS 1

Over-the-Counter Options

• Loperamide is effective for diarrhea management but may cause abdominal pain, bloating, nausea, and constipation; careful dose titration is recommended 1
• Certain antispasmodics may help with global symptoms and abdominal pain, though side effects include dry mouth, visual disturbance, and dizziness 1
• Probiotics may be effective for global symptoms and abdominal pain, but no specific strain can be recommended; a 12-week trial is reasonable 1

Second-Line Treatments

Gut-Brain Neuromodulators

• Tricyclic antidepressants (TCAs) are effective second-line treatments for global symptoms and abdominal pain 1
  • Start at low dose (e.g., amitriptyline 10mg once daily) and titrate slowly to 30-50mg once daily 1
  • Require careful explanation of rationale and counseling about side effects 1
• Selective serotonin reuptake inhibitors (SSRIs) may be effective for global symptoms 1
  • Consider particularly when concurrent mood disorders are present 1

IBS-D Specific Medications

• 5-HT3 receptor antagonists are the most efficacious drug class for IBS-D 1

  • Alosetron is effective but restricted to women with severe IBS-D under a risk management program due to rare but serious adverse events including ischemic colitis 1
  • Ondansetron (4mg once daily, titrated to maximum 8mg three times daily) is a reasonable alternative where alosetron is unavailable 1
  • Constipation is the most common side effect 1

• Eluxadoline (mixed opioid receptor drug) is efficacious for IBS-D 1, 2

  • Contraindicated in patients with prior sphincter of Oddi problems, cholecystectomy, alcohol dependence, pancreatitis, or severe liver impairment 1
  • Side effects include constipation, nausea, and headache 1

• Rifaximin (non-absorbable antibiotic) is effective for IBS-D 1, 3

  • Recommended dose is 550mg three times daily for 14 days 3
  • Patients who experience symptom recurrence can be retreated up to two times with the same regimen 3
  • Effect on abdominal pain may be limited 1
  • Has a favorable safety profile compared to other approved agents 4

Other Considerations

• Bile acid sequestrants (e.g., cholestyramine) may be considered for patients with cholecystectomy or suspected bile acid malabsorption 1
• Psychological therapies (cognitive behavioral therapy, hypnotherapy) can be effective for global symptoms and abdominal pain 1
  • Consider these approaches when symptoms are refractory to drug treatment for 12 months 1

Treatment Algorithm

1. Start with lifestyle modifications and dietary advice 1
2. For diarrhea control: Loperamide with careful dose titration 1
3. If inadequate response, add antispasmodics for pain and bloating 1
4. For persistent symptoms, consider second-line therapies:
   • For predominant pain and global symptoms: TCAs (first choice) or SSRIs 1
   • For predominant diarrhea: 5-HT3 antagonists, eluxadoline, or rifaximin 1
5. For refractory symptoms: Consider psychological therapies 1

Common Pitfalls and Caveats

• Avoid insoluble fiber (e.g., wheat bran) as it may worsen symptoms 1
• When using TCAs, start at low doses and titrate slowly to minimize side effects 1
• Carefully screen patients before prescribing eluxadoline due to contraindications 1
• Rifaximin is not effective for travelers' diarrhea caused by pathogens other than E. coli 3
• Alosetron should only be used in women with severe IBS-D under risk management protocols due to risk of ischemic colitis 1