In a randomized double-blind, placebo-controlled study, researchers at the University of Pittsburgh School of Medicine found that the drug relieved some symptoms of IBS and improved the well-being of people with IBS.
"This study points out the benefits of this drug as a potential new and improved treatment for IBS, a disease that is very difficult for physicians to manage," said George Arnold, M.D., F.A.C.P., clinical professor of medicine at the University of Pittsburgh School of Medicine and principal investigator in the study.
IBS is a chronic gastrointestinal disorder that affects 14-24 percent of women and 5-19 percent of men in western populations and is characterized by abdominal pain, altered bowel habits and abdominal bloating. It generally has been treated with high-fiber diet, drugs or both.
The study found that the percentage of participants experiencing an improvement in overall well-being was significantly greater (63.3 percent) in the paroxetine group than the placebo group (26.3 percent). The percentage of participants experiencing an improvement in bowel movements was significantly greater in the paroxetine recipients (58.6 percent) than the placebo recipients (32.4 percent). There was a significant improvement in food avoidance and work function for those on paroxetine. There was no significant improvement in abdominal pain or bloating between the paroxetine and placebo groups.
"This study showed that in absence of depression, paroxetine helped irritable bowel syndrome," said Dr. Arnold. "This is a medicine that has been in use for some years and is safe with no long term side effects, which is a problem with current medications for IBS."
The effectiveness of paroxetine, a selective serotonin reuptake inhibitor (SSRI), has been reported in case reports but not in controlled studies. SSRIs are considered first line treatments in psychiatric illnesses such as major depression and generalized anxiety disorder, which are found in 50 to 90 percent of patients with IBS, according to Dr. Arnold, who is a gastroenterologist at the University of Pittsburgh Medical Center's (UPMC) Shadyside Hospital.
The two-part clinical study enrolled a total of 110 participants with IBS. Group one consisted of 98 participants who at enrollment were consuming a low-fiber or average-fiber diet, who were then put on a high-fiber diet. In this group, 26 percent reported an overall improvement in well-being. Abdominal pain and bloating decreased in 22 percent and 26 percent of participants respectively.
Group two consisted of 12 participants who at enrollment were already consuming a high-fiber diet plus the 69 participants from group one who reported an inadequate response to the high-fiber diet. Group two participants continued to consume their high-fiber diet throughout the study and were randomized to receive a 12-week course of either paroxetine or a placebo. All participants began with a dosage of paroxetine of 10 mg/day. Participants who experienced improvement in their condition were instructed to continue at the same dosage while those who experienced no improvements were instructed to increase their dosage.
Because SSRIs have a well-recognized effect on depression, the researchers also performed a separate analysis of participants and showed that the improvement in well-being held true for non-depressed patients taking paroxetine.
Also participating in the study were Gary Tabas, M.D., Mary Beaves, R.N., Jiping Wang, M.D., Paul Friday, Ph.D. and Houssam Mardini, M.D.
The study was funded by the Competitive Research Fund of the Shadyside Hospital Foundation of Pittsburgh.