An atypical antidepressant is any antidepressant medication that acts in a manner that is different from that of most other antidepressants. Atypical antidepressants include agomelatine, bupropion, iprindole, mianserin, mirtazapine, nefazodone, opipramol, tianeptine, and trazodone.[1][2][3] The agents vilazodone and vortioxetine are partly atypical. Typical antidepressants include the SSRIs, SNRIs, TCAs, and MAOIs, which act mainly by increasing the levels of the monoamine neurotransmitters serotonin and/or norepinephrine.[1][2][3] Among TCAs, trimipramine is an atypical agent in that it appears not to do this.[3] In August 2020, esketamine (JNJ-54135419) was approved by the U.S. Food and Drug Administration (FDA) for the treatment of treatment-resistant depression with the added indication for the short-term treatment of suicidal thoughts.[4]
Buprenorphine/samidorphan (ALKS-5461) is an antidepressant with a novel mechanism of action which was formerly under development and considered an atypical antidepressant.[5] They act faster than available antidepressants.[5]