ONSET OF ACTION AND COMPARATIVE EFFICACY OF ANTIDEPRESSANTS IN MAJOR DEPRESSION

Objectives: To study the time to onset of action and comparative efficacy of three antidepressants from three different classes.

Participants and Methods: 132 patients diagnosed as depressive episode were randomized to receive sertraline, imipramine or des-venlafaxine. Assessments were made at 3rd day, 7th day, 14th day, 21st day, 1 month and 3 months using the Hamilton rating scale for depression and Hamilton rating scale for anxiety.

Results: 5 patients (17.86%) in sertraline and imipramine (16.67%) groups and 5 (15.62%) patients in des-venlafaxine group showed onset of action by the 7th day. 82.14% patients in sertraline group had onset of action by 14 days as compared to 50% in des-venlafaxine and 66.67% in imipramine group. At the end of first month, 82.14% patients of sertraline group showed response (at least 50% reduction in Hamilton rating scale for depression score) as compared to 37.50% in des-venlafaxine and 60% in imipramine group. 46.63% of patients in the sertraline group showed remission at the end of first month as compared to 12.5% in the des-venlafaxine and 33.3% in the imipramine group.

Conclusions: The long held belief that antidepressants take at least 2 weeks to show onset of action is debatable. Many patients start improving within 1 week. Early onset of action also leads to a higher rate of response and remission.