What is "tricyclic antidepressant"

n. an antidepressant drug that acts by blocking the reuptake of norepinephrine and serotonin and thus making more of those substances available to act on receptors in the brain [syn: tricyclic, tricyclic antidepressant drug]

Tricyclic antidepressants (TCAs) are chemical compounds used primarily as antidepressants. TCAs were first discovered in the early 1950s and marketed later in the decade. They are named after their chemical structure, which contains three rings of atoms. Tetracyclic antidepressants (TeCAs), which contain four rings of atoms, are a closely related group of antidepressant compounds.

Although TCAs are sometimes prescribed for depressive disorders, they have been largely replaced in clinical use in most parts of the world by newer antidepressants such as selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs) and norepinephrine reuptake inhibitors (NRIs). Adverse effects have been found to be of a similar level between TCAs and SSRIs.