Background: Irritable Bowel Syndrome (IBS) is the most common cause of GI-man visits. Recent trend was seen towards neurotransmitters, however these drugs are expensive. We have determined the effects of fluoxetine, nortriptyline and amitriptyline in IBS patients referred to a private GI clinic in Tehran in 2000.

Materials and Methods: 173 patients had entered this clinical trial. Diagnosis was made according to the Rome criteria. Patients were concurrently allocated in three groups. Fluoxetine 20 mg/d, amitriptyline 25 mg/d and nortriptyline 25 mg/d were given to individuals of each group, respectively. Pre- and post-test data were collected and recorded in a checklist.

Results: The study population included 53 cases as the “Constipation group”, 57 as the “Diarrhea group” and 63 as the “Abdominal Pain group”. 50 patients received fluoxetine, 69 nortriptyline and 54 received amitriptyline. Fluoxetine has effectively increased the defecation times of constipated individuals (From 2.56/week to 12/week, P<0.02), but was ineffective for diarrhea individuals (NS). Amitriptyline has improved the defection pattern of constipated and diarrhea individuals (2.31/week to 6.54/week and 17.26/week to 11.79/week, respectively, P<0.02). Nortriptyline had the same effect as amitriptyline (2.67/week to 6.33/week and 20.64/week to 12.23/week, respectively, P<0.01). Fluoxetine and TCAs were significantly improved the abdominal pain, bloating and general performance of affected patients. Amitriptyline has shown more side effects than nortriptyline and fluoxetine (P<0.01).

Conclusion: Fluoxetine was shown to be more effective than TCAs in constipated patients, however in patients with diarrhea it seems to be less effective.