What is the treatment plan for diarrhea-predominant Irritable Bowel Syndrome (IBS-D)?

Treatment Plan for Diarrhea-Predominant IBS (IBS-D)

The treatment of IBS-D should follow a step-wise approach starting with dietary and lifestyle modifications, followed by pharmacological interventions targeting specific symptoms, and psychological therapies for refractory cases.

Step 1: Dietary and Lifestyle Modifications

• Regular exercise is recommended as it can provide beneficial effects for IBS symptoms 1, 2
• Low-FODMAP diet trial supervised by a trained dietitian is recommended with moderate evidence strength 2
• Soluble fiber supplementation (e.g., ispaghula) starting at 3-4g/day and gradually increasing 2
• Avoid insoluble fiber (e.g., wheat bran) as it may worsen symptoms 2
• Identify and eliminate food triggers
• Maintain adequate hydration
• Reduce caffeine and alcohol intake

Step 2: First-Line Pharmacological Treatments

For patients with inadequate response to dietary and lifestyle modifications:

• Loperamide 4-12 mg daily (can be divided or single 4 mg dose at night) for diarrhea control 2

  • Can be used prophylactically when diarrhea is anticipated
  • Improves stool frequency and rectal urgency but has mixed results for abdominal pain 3

• Peppermint oil for antispasmodic effects 2, 4

Step 3: Second-Line Pharmacological Treatments

For patients with persistent symptoms despite first-line treatments:

• Tricyclic antidepressants (TCAs) such as amitriptyline 2

  • Start at 10 mg at bedtime
  • Titrate slowly by 10 mg/week as needed
  • Target dose: 25-50 mg at bedtime
  • TCAs should be first choice among neuromodulators 1

• Rifaximin (Xifaxan) 550 mg three times daily for 14 days 5, 6

  • FDA-approved for IBS-D
  • Can be repeated for symptom recurrence
  • Works by modulating gut microbiota, reducing inflammation, and normalizing visceral hypersensitivity

• Eluxadoline (Viberzi) 7, 6

  • FDA-approved for IBS-D
  • Mixed μ- and κ-opioid receptor agonist/δ-opioid antagonist
  • Decreases GI motility, fluid secretion, and visceral pain perception

• Cholestyramine for patients with evidence of bile acid malabsorption 2

  • Most effective when 75SeHCAT retention is <5%

• Selective serotonin reuptake inhibitors (SSRIs) for patients with comorbid anxiety disorders 2

Step 4: Treatments for Refractory Cases

For patients with severe or persistent symptoms despite above treatments:

• Psychological therapies 1, 2

  • Cognitive-behavioral therapy
  • Gut-directed hypnotherapy
  • Dynamic psychotherapy
  • Stress management/relaxation techniques
  • Particularly beneficial for patients who connect symptom flares with stress or have anxiety/depression

• Alosetron (for women with severe IBS-D refractory to conventional therapy) 6

  • 5-HT3 antagonist
  • Slows GI motility
  • Available under restricted license due to risk of ischemic colitis and severe constipation

• Octreotide for severe, persistent diarrhea unresponsive to other measures 2

  • Typical dosage: 100 μg three times daily

Monitoring and Follow-Up

• Use symptom diaries to identify triggers and monitor treatment response 2
• Review efficacy after 3 months of treatment and discontinue if no response 1
• Consider referral to gastroenterology when:
  • Diagnostic uncertainty exists
  • Symptoms are severe or refractory to first-line treatments
  • Patient requests specialist opinion

Important Considerations and Precautions

• Rule out alarm symptoms that would warrant further investigation before diagnosing IBS-D

• Consider diagnostic tests to exclude other conditions:

  • Full blood count, C-reactive protein or ESR, and coeliac serology
  • Fecal calprotectin in patients under 45 years with diarrhea
  • Consider 23-seleno-25-homotaurocholic acid scanning to exclude bile acid malabsorption

• Avoid:

  • Wheat bran and insoluble fiber as they can worsen symptoms
  • IgG antibody-based food elimination diets (low evidence)
  • Gluten-free diets unless celiac disease is confirmed
  • Long-term anxiolytic use due to potential for dependence
  • Unnecessary colonoscopies unless alarm symptoms are present