Medical XpressDrug combination for treatment-resistant depression not more effective than a single antidepressantMedical XpressPsychiatrists and GPs increasingly combine mirtazapine with an SSRI (selective serotonin reuptake inhibitor) or SNRI (serotonin-noradenaline reuptake inhibitor) antidepressant for patients whose depression does not respond to a single antidepressant.