Pharmacological Management of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is the most common diagnosis in clinical gastroenterology. It is estimated that approximately 10%–15% of the general adult population is affected.

For this review, the important role of nonpharmacological therapies, including dietary and lifestyle modification, was not considered.

IBS is a chronic functional gastrointestinal disorder characterized by abdominal pain and/or discomfort associated with altered defecation. Other common symptoms include bloating, straining, rectal urgency, and the sensation of incomplete evacuation.

The current Rome III criteria for IBS require the presence of recurrent abdominal pain and/or discomfort at least 3 days/month in the past 3 months that is associated with 2 or more of the following: improvement with defecation, onset associated with a change in stool frequency or in form (appearance) of stool. Symptoms have to be present for at least 6 months.

Further subclassification is based on the predominant stool consistency: IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), IBS with mixed pattern (IBS), and unsubtyped IBS.

Current pharmacological treatments are generally aimed at improving one or more of the predominant symptoms, such as abdominal pain, constipation, or diarrhea. Commonly used pharmacological therapies for IBS include linaclotide, lubiprostone, polyethylene glycol (PEG_S) laxative, rifaximin, alosetron, loperamide, tricyclic antidepressants (TCA), selective serotonin reuptake inhibitors (SSRI_S), and antispasmodics.