Irritable Bowel Syndrome Management

Introduction to Treatment

• The American Gastroenterological Association (AGA) suggests using antispasmodics like dicyclomine in patients with IBS (conditional recommendation, low certainty in evidence) 1
• Antispasmodics demonstrated improvement in abdominal pain compared to placebo (RR 0.74; 95% CI 0.59-0.93) 1
• Dicyclomine specifically showed significant improvement in pain in clinical trials 2

Pharmacological Treatment

• The American Gastroenterological Association (AGA) recommends using antispasmodics like dicyclomine, with standard dosing being 10-20mg three times daily 1
• Tricyclic antidepressants (TCAs) are recommended as the first-line drug for IBS pain management, with a relative risk of persistent pain of 0.53 (95% CI: 0.34-0.83), and a starting dose of 10 mg amitriptyline at bedtime, titrating up to 30-50 mg based on response 3, 4
• Desipramine or nortriptyline (10-25mg at bedtime) have lower anticholinergic effects than amitriptyline and are better tolerated in patients with IBS-C or mixed type 4
• Dicyclomine (10-20mg three times daily) is a second-ranked treatment for IBS pain, with a relative risk of persistent pain of 0.64 (95% CI: 0.49-0.84) 5
• Enteric-coated peppermint oil (0.2-0.4mL three times daily) is ranked first for global symptom management in IBS and third-ranked for abdominal pain, with a moderate strength of evidence 5, 3
• Loperamide (2-4mg as needed) is effective for controlling diarrhea and can be used on an as-needed basis 5, 3
• Eluxadoline is effective for the IBS-D component in mixed IBS, but is contraindicated in patients with a history of pancreatitis, sphincter of Oddi problems, cholecystectomy, or alcohol dependence 5
• Alosetron is recommended for women with diarrhea-predominant IBS who have not responded to conventional therapy, starting with a dose of 0.5 mg once daily, which may be increased to 0.5 mg twice daily if tolerated 5
• Rifaximin, a non-absorbable antibiotic, is effective for diarrhea-predominant IBS, but has limited effect on abdominal pain 5
• Linaclotide, a guanylate cyclase-C agonist, and lubiprostone, a chloride channel activator, are recommended for patients with constipation-predominant IBS, with lubiprostone being particularly appropriate as it addresses constipation but has nausea as a side effect 5

Non-Pharmacological Treatment

• Cognitive behavioral therapy (CBT) shows efficacy for global IBS symptoms, with a moderate strength of evidence 5, 6
• Gut-directed hypnotherapy is effective for psychological stress and maladaptive cognitive processes in patients with IBS, with a moderate strength of evidence 6
• Mindfulness-based stress reduction helps with psychological stress and negative emotions in patients with IBS, with a moderate strength of evidence 6
• Regular exercise is recommended for all IBS patients, with a low strength of evidence 5
• Dietary modifications, including a low FODMAP diet, may help reduce symptoms in patients with IBS, with a low strength of evidence 5
• Soluble fiber supplementation, starting at 3-4 g/day, may help reduce symptoms in patients with IBS, with a low strength of evidence 5

Safety and Monitoring

• Regular use of antispasmodics like dicyclomine in constipation-predominant IBS may be limited due to anticholinergic effects 1
• Use with caution in elderly patients who may be more sensitive to anticholinergic effects 1, 2
• Regular monitoring is essential, especially when initiating new treatments, with a high strength of evidence 6
• Combining pharmacological and psychological approaches may provide better outcomes for refractory cases, with a moderate strength of evidence 6