Antidepressant-like activity of tramadol in mice

OBJECTIVE: To evaluate antidepressant-like effect of tramadol in mice. MATERIALS AND METHODS: Tramadol was administered at three different doses (10, 20, and 40 mg/kg, i.p.) once daily for 7 days to Swiss albino mice of either sex. The immobility period of control and drug-treated mice was recorded in forced swim test (FST). The antidepressant effect of tramadol was compared to that of fluoxetine (20 mg/kg, i.p.), administered for seven successive days. RESULTS: Tramadol produced significant antidepressant effect at all the three (10, 20, and 40 mg/kg) doses, as indicated by reduction in immobility times of drug-treated mice compared to control mice. The efficacy of tramadol at doses of 10 and 20 mg/kg was comparable to that of fluoxetine, but antidepressant activity in animals administered with tramadol 40 mg/kg was significantly less as compared to fluoxetine-pretreated mice. CONCLUSION: The results of the present study indicate antidepressant-like activity of tramadol.