Tricyclic Antidepressants, also known as TCAs, are chemical compounds that are used in the treatment of depression. First developed in the 1950s, they have largely replaced the other classes of drugs; SSRIs, SNRIs and NRIs, that have traditionally been used for depression treatment. This has happened because of the lack of unpleasant side-effects that occur with the older treatments.
See also: Antidepressant