Tricyclic antidepressants(TCAs) are a class of medications that are used primarily as antidepressants. TCAs were discovered in the early 1950s and were 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.
TCA overdose is a significant cause of fatal drug poisoning. The severe morbidity and mortality associated with these drugs is well documented due to their cardiovascular and neurological toxicity.