The management of the
irritable bowel syndrome (IBS) remains unsatisfactory. For
abdominal pain,
antispasmodics are, at best, of only modest efficacy.
Tricyclic antidepressants in low dose are useful (with the number needed to treat being three), but side effects and patient concerns regarding use of a centrally acting agent for depression remain limitations.
Selective serotonin reuptake inhibitors are of uncertain efficacy in IBS.
Opioid agonists, especially
loperamide, are useful for
diarrhea but not for
pain in IBS; rebound
constipation also remains a problem.
Bile salt sequestering agents are not of established value in IBS but seem to be useful clinically in a small group of IBS patients with
diarrhea. Aloestron, a 5HT(3) antagonist, should be reserved, if available, for women with severe
diarrhea predominant IBS who have failed to respond to conventional
therapy, and started at a low dose. Fiber and bulking agents may help
constipation in some trials, but the evidence that they are efficacious in IBS is equivocal; they are frequently prescribed as first-line drugs for IBS regardless of the primary bowel disturbance but often increase bloating, gas, and
pain. Laxatives are not of established value in IBS but are often taken by patients with
constipation predominant IBS.
Tegaserod, a partial 5HT(4) agonist, is now available in the United States and other countries for use in women with IBS whose primary bowel symptom is
constipation; its efficacy in men and in those with alternating bowel habits is unknown. Probiotics are of uncertain efficacy. Chinese herbal medicine data are insufficient. Other new drugs in development include the
cholecystokinin antagonists and novel visceral
analgesics. Both current and potential
therapies for IBS are reviewed in this article.