What are the newest treatments for irritable bowel syndrome (IBS)?

Newest Treatments for Irritable Bowel Syndrome (IBS)

Linaclotide (290 mcg once daily) is the most effective newest treatment for IBS with constipation (IBS-C), showing statistically significant improvement in both abdominal pain and bowel movements compared to placebo. 1

First-Line Treatments Based on IBS Subtype

For All IBS Subtypes

• Antispasmodics: Recommended as first-line treatment for trapped wind pain and associated gastrointestinal symptoms 2
  • Hyoscine (Buscopan) 10mg up to three times daily
  • Dicyclomine 10-20mg three to four times daily

For IBS with Constipation (IBS-C)

1. Linaclotide (LINZESS): 290 mcg once daily 1

   • Clinical trials showed 12-13% of patients were combined responders (improved abdominal pain and complete spontaneous bowel movements) vs 3-5% with placebo
   • Take with food to reduce nausea side effects

2. Lubiprostone: 8 mcg twice daily for women with IBS-C 3

   • Should be taken with food and water
   • Capsules should be swallowed whole

For IBS with Diarrhea (IBS-D)

• Rifaximin: A non-absorbable antibiotic that has shown efficacy for IBS-D 4
• Eluxadoline: Effective for improving abdominal pain and stool consistency 4
• Alosetron: Approved only for women with severe IBS-D 4

Second-Line Treatments

Neuromodulators

• Low-dose tricyclic antidepressants (TCAs): Effective for abdominal pain 2

  • Amitriptyline 10mg at bedtime (starting dose)
  • Provides global symptom relief (RR 0.67; 95% CI 0.54-0.82)

• Selective serotonin reuptake inhibitors (SSRIs): Preferred for patients with concurrent mood disorders 2

  • Improves overall well-being and perception of symptoms

Combination Therapies

• Antispasmodic + simethicone: Recommended for pain and bloating 2
• Neuromodulators + antidepressants: Recommended for severe pain 2

Dietary and Lifestyle Modifications

Dietary Approaches

• Low FODMAP diet: Effective for reducing bloating and pain (RR 0.51 [95% CI 0.37-0.70]) 2

  • Should be implemented under dietitian supervision
  • Recommended for moderate to severe gastrointestinal symptoms

• Mediterranean diet: Recommended for patients with psychological-predominant symptoms 2

  • Should be implemented for at least 12 weeks

• Fiber management: 2

  • Increase soluble fiber (ispaghula/psyllium) starting with 3-4g/day
  • Decrease fiber for IBS-D patients

Lifestyle Modifications

• Regular exercise: Recommended as first-line treatment 2
• Peppermint oil: Can help relieve IBS symptoms 2, 5
  • Has shown highest efficacy in some meta-analyses

Treatment Algorithm

1. Start with symptom assessment to determine IBS subtype (IBS-C, IBS-D, IBS-M)
2. Begin with dietary and lifestyle modifications:
   • Low FODMAP or Mediterranean diet based on symptom pattern
   • Regular exercise
   • Peppermint oil
3. Add first-line pharmacological treatment based on subtype:
   • IBS-C: Linaclotide or lubiprostone
   • IBS-D: Rifaximin, eluxadoline, or alosetron (women only)
   • All subtypes: Appropriate antispasmodic
4. If inadequate response after 4-6 weeks, add or switch to:
   • Neuromodulators (TCAs or SSRIs)
   • Combination therapy
5. Consider referral to gastroenterology if symptoms are severe or refractory to first-line treatments

Important Caveats

• Avoid ineffective treatments:

  • Insoluble fiber (wheat bran) may worsen symptoms 2
  • Conventional analgesics or opioids may worsen symptoms 2
  • Discontinue ineffective treatments after 12 weeks 2

• Safety considerations:

  • Rifaximin has the most favorable safety profile among the approved agents for IBS-D 4
  • Lubiprostone is contraindicated in patients with known or suspected mechanical gastrointestinal obstruction 3
  • Linaclotide and lubiprostone may cause diarrhea as a side effect 1, 3

• Regular reassessment: Modify treatment approach after 4-6 weeks if no improvement is seen 2