Influence of sildenafil on the antidepressant activity of bupropion and venlafaxine in the forced swim test in mice

► Nitric oxide is implicated in the mechanism of action of antidepressant drugs. ► Sildenafil is often used concomitantly with antidepressant drugs. ► Effect of sildenafil on the activity of bupropion and venlafaxine was investigated. ► Sildenafil potentiated the anti-immobility action of the studied drugs. ► The interactions may have pharmacodynamic and/or pharmacokinetic basis.