EFFICACY OF DULOXETINE COMPARED WITH IMIPRAMINE IN THE TREATMENT OF GENERALIZED ANXIETY DISORDER IN INDIAN PATIENTS
Generalized anxiety disorder (GAD) is the most frequent anxiety disorder with lifetime prevalence of four to six percent, accounting for one third of the total cost of treating psychiatric disorders. Duloxetine, a very potent and balanced reuptake inhibitor of both serotonin and noradrenaline, is approved for treating GAD. Imipramine, a tricyclic acid antidepressant, has been in use to treat GAD because of its established efficacy, despite the availability of more tolerable drugs. To the best of our knowledge, duloxetine has not been compared earlier with imipramine for efficacy in GAD patients. Efficacy of duloxetine in Indian GAD patients has also not been studied earlier. The efficacy of duloxetine was compared with that of imipramine in GAD, in this prospective observer blinded parallel group comparative study. Consenting adult patients (N=60) meeting DSM-IV criteria for MDD who completed six weeks of treatment with, either duloxetine (40 mg) or imipramine (150 mg), were compared for improvement with their base line disease severity, measured by scores on the Hamilton Anxiety (HAM-A) Rating Scale and Clinical Global Impression (CGI) scale. The primary efficacy measure was mean change from baseline to endpoint on the HAM-D scale. The total change in HAM-A score from the baseline score in imipramine group was - 18.83 (±6.74) and that in duloxetine group was -21.10(±7.07) exhibiting a total improvement of 63.68% and 58.66%, respectively. The total change in CGI score in imipramine group was -2.67 (±0.48) and that in duloxetine group was - 2.77(±1.17). Response, defined by a decrease of >50% in the HAM-A Scores, was seen in 22 cases (73.3%) on imipramine and 21(70%) cases on duloxetine. Remission, which was defined as a HAM-A Score≤7 was seen in 8 (26.7%) cases on imipramine and 9 (30%) cases on duloxetine. There was no statistically significant difference between the two groups in response and remission rates (p>0.05). The efficacy of duloxetine and imipramine is comparable in GAD with no significant difference in response and remission rates.