Augmentation of antidepressant effects of duloxetine and bupropion by caffeine in mice

There is an unmet need in the treatment of depression suggesting requirement of new therapeutic approaches having better efficacy and safety profile. Patients receiving antidepressant therapy generally consume caffeine in the form of tea or coffee. The objective of the present study was to evaluate the augmentation of antidepressant effects of duloxetine and/or bupropion with caffeine. Male Swiss Albino mice received treatment of normal saline (10 ml/kg), 'caffeine alone' (10 mg/kg), 'duloxetine alone' (10 mg/kg), 'bupropion alone' (10 mg/kg), caffeine + duloxetine (5 mg/kg, each), bupropion + caffeine (5 mg/kg, each), and bupropion + duloxetine (5 mg/kg, each) through the intra-peritoneal route. The immobility period was analyzed 30 min after the treatment in forced swim and tail suspension tests. Norepinephrine, dopamine, and serotonin levels were analyzed in hippocampus, cerebral cortex and whole brain using HPLC with fluorescence detector. Euthanasia was performed 1 h after treatment. Comparison between vehicle treated group and other groups showed significant decrease in immobility in all drug treated groups in both antidepressant models. Caffeine plus duloxetine treated group was better among the combination treated groups in terms of decrease in immobility and increase in norepinephrine, dopamine, and serotonin levels in hippocampi, cerebral cortices, and whole brain when compared to their respective monotherapy treated groups. These combination approaches may help in reducing the dose of duloxetine/bupropion, and consequently lower the associated side/adverse effects.