Management of IBS-C Patients with Loose Stools

Introduction to Alternative Treatments

The British Society of Gastroenterology provides a strong recommendation with moderate-quality evidence for lubiprostone in IBS-C, as it is significantly less likely to cause diarrhea compared to other secretagogues used for IBS-C, making it an ideal replacement for patients who cannot tolerate tenapanor due to loose stools 1

Lubiprostone (8 mcg twice daily) has a more favorable bowel side effect profile, with a lower risk of diarrhea, unlike linaclotide, plecanatide, and tenapanor, which all commonly cause diarrhea 1, 2
Lubiprostone demonstrates improvement in both the FDA composite endpoint (abdominal pain + bowel movements) and abdominal pain alone, and is FDA-approved for IBS-C in women at 8 mcg twice daily 2, 3
Linaclotide (290 mcg once daily) is the most efficacious secretagogue for IBS-C, but diarrhea remains a common side effect, making it not recommended for patients with loose stools 1, 3

Tricyclic antidepressants (TCAs), such as amitriptyline, can be used for global symptoms and abdominal pain, starting with 10 mg once daily and titrating to 30-50 mg once daily, and work through gut-brain modulation without causing diarrhea 4, 3
Polyethylene glycol (PEG) laxatives can be used as first-line therapy for constipation symptoms without the diarrhea risk of secretagogues, but evidence for abdominal pain improvement is limited 3

Nausea is a frequent side effect of lubiprostone that patients must be warned about, and can be mitigated by taking the medication with food 1, 3
When switching from tenapanor to lubiprostone, it is recommended to discontinue tenapanor and allow 2-3 days for washout, then start lubiprostone 8 mcg twice daily with food to minimize nausea 3, 1