The most important classes of antidepressants are the selective serotonin reuptake inhibitors ( SSRIs ) , serotonin-norepinephrine reuptake inhibitors ( SNRIs ) , tricyclic antidepressants ( TCAs ) and monoamine oxidase inhibitors ( MAOIs ) .
There are different types of antidepressant , called monoamine oxidase inhibitors ( MAOIs ) , tricyclic antidepressants ( TCAs ) , tetracyclic antidepressants ( TeCAs ) , selective serotonin reuptake inhibitors ( SSRIs ) and serotonin-norepinephrine reuptake inhibitors ( SNRIs ) .