Irritable bowel syndrome is a common problem that decreases quality of life and increases health care utilization in patients with the disorder. Persons with irritable bowel syndrome are estimated to have greater disability, along with a rate of absenteeism from work that is threefold higher and a rate of average health care costs that is twofold higher than healthy control subjects. Jailwala and associates conducted a systematic review of the published literature on pharmacologic treatment of irritable bowel syndrome to provide evidence-based guidelines for physicians.

A comprehensive search of several medical databases was performed to identify all English-language studies. Studies were included in the evaluation if: (1) treatment of irritable bowel syndrome was addressed; (2) adult patients were studied; (3) more than 10 patients who received a pharmacologic agent for at least two weeks were included in the study; (4) a placebo control group was included; (5) outcomes of global status, individual symptoms of irritable bowel syndrome, or both, were reported; and (6) a randomized, double-blind, parallel group or crossover design was used. A total of 70 studies met these criteria, with a single pharmacologic agent evaluated in 66 trials and a combination of two or more agents examined in four trials. Most of the trials were conducted in Europe, and most of them diagnosed irritable bowel syndrome using criteria modified from the standard criteria.

Thirteen trials evaluated the efficacy of bulking agents, with only four agents showing a beneficial effect of treatment. Improvement occurred mainly in nonspecific outcomes such as constipation, ease of stool passage and frequency of satisfaction with bowel movements. No significant improvement was noted in more specific symptoms such as stool frequency, abdominal pain and bloating.

Thirteen of 16 studies of muscle relaxants demonstrated efficacy with significant improvement in pain. In only two of six trials were prokinetic agents found useful. All four studies of loperamide reported an improvement in diarrhea but no change in pain or abdominal distention. In all seven trials, psychotropic drugs were found to be beneficial.

The largest number of trials focused on smooth-muscle relaxants and bulking agents. In patients with a predominance of pain, smooth-muscle relaxants were helpful. The utility of bulking agents was less clear. Antidepressants might be useful in patients with comorbid depressive or anxiety disorders, although it is less clear whether antidepressants improve specific symptoms or have any global effect in patients without psychiatric disorders. The use of selective serotonin reuptake inhibitors has not been well studied, and prokinetic agents are not helpful. Loperamide decreased diarrhea but did not decrease abdominal pain.

The authors conclude that a multidimensional approach is best in the management of irritable bowel syndrome, including patient education, reassurance and careful dietary modification. Pharmacologic treatment should target major symptoms, and patients should be monitored for adverse effects.