What is the role of medications in the treatment of irritable bowel syndrome (IBS)?

Updated: Dec 30, 2019
  • Author: Mohammad F El-Baba, MD; Chief Editor: Carmen Cuffari, MD  more...
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Pharmacotherapy is recommended for patients with moderate-to-severe irritable bowel syndrome (IBS) symptoms that cause disruptions in activity. Treatment is symptomatic and is directed at the most predominant symptom (eg, dietary fiber supplementation and stool softeners for constipation, antidiarrheals for diarrhea, smooth muscle relaxants for pain). A better understanding of the pathophysiology of irritable bowel syndrome and the role of neurotransmitters and receptors involved in the GI sensory and motor functions have provided opportunities for the development of newer therapeutic agents. The role of serotonin in the pathophysiology of irritable bowel syndrome has drawn much attention, and agonists and antagonists at 5-hydroxytryptamine (5-HT) receptors have been approved for the treatment of subgroups of patients with irritable bowel syndrome.

Saps et al conducted a double-blind, placebo-controlled trial examining amitriptyline efficacy in treating children (n=83) with pain-predominant functional GI disorders (eg, irritable bowel syndrome, functional abdominal pain, functional dyspepsia). [28] Participants were randomized to receive 4 weeks of either placebo or amitriptyline (weight < 35 kg = 10 mg/d, weight >35 kg = 20 mg/d). The primary outcome, overall response to treatment (ie, child’s pain assessment and sense of improvement), indicated no difference between placebo and amitriptyline (57.5% improvement and 2.5% worsening with placebo compared with 63% improvement and 5% worsening with amitriptyline; P=0.63). Children with severe baseline pain in both groups had poorer response to treatment. Although placebo and amitriptyline both produced a therapeutic response of pain reduction, this study showed no significant difference between placebo and amitriptyline.

Newer drugs have been approved for the treatment of adults with chronic idiopathic constipation (CIC) and irritable bowel syndrome. Lubiprostone, a locally acting chloride channel agonist, has been approved in the United States for the treatment of CIC in adults and for irritable bowel syndrome with predominant constipation in women at least 18 years old. Linaclotide (Guanylin Cyclase-C receptor agonist) is another drug that was approved for treatment in adult patients with irritable bowel syndrome and constipation. Currently, lubiprostone and linaclotide are not FDA approved in the United States for use in children. A study showed lubiprostone to be effective in the management of children with CIC. [29]

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