The efficacy of Fluoxetin and Doxepin in treatment of irritable bowel syndrome

Background: This study compares the efficacy of Fluoxetine (serotonin-selective reuptake inhibitors-SSRI) with Doxepin (tricyclic antidepressants –TCAs- antihistaminic) in treatment of irritable bowel syndrome (IBS).

Methods: This randomized clinical trail recruited 200 patients who had referred to Kermanshah Imam Reza hospital during the period 2006-7. All the patients had been diagnosed with IBS bases on Rome II criteria of IBS and were randomized into two groups. The patients were then received treatment with anti-depresants Fluoxetine (20mg /day) in one group and Doxepin (20mg/ day) in the other group for 12 weeks. In order to compare the quantitative variables, we used Leven and t-test. Chi-2 test was used for qualitative variables.

Results: There was no statistically significant difference between mean age in Fluoxetine (37±98 years) and Doxipin group (37±02 years). The number of males in Fluoxitine and Doxipin groups was 40 and 42 respectively, which indicated no difference. Doxipin proved more effective on bloating, decreaing stool consistency, need for urgency and incomplete evaluation than Fluoxetine. On the other hand, the effect of Fluoxetin on abdominal pain and increasing of defecation was greater than Doxipin (p<0.05).The figure for positive response to improvement of 50% was 67% and 52% for Doxipin and Fluoxetine groups respectively (p<0.022).

Conclusion: Our results indicated higher efficacy of Doxipin, the new TCA generation, in reducing most symptoms in patients with IBS, making it the recommended anti-depressant in treating IBS with no constipation.