Tricyclic Antidepressants (TCAs) are so-called because of their molecular structure, which contains three rings of atoms. They act mainly by inhibiting the reuptake of both norepinephrine and serotonin. Other receptors that might also experience a TCA induced inhibition are muscuranic, alpha1 adrenergic, and histaminic receptors.
The TCAs of interest in the treatment of depression include amitriptyline (Elavil, Endep, Tryptanol), amoxapine (Asendin, Asendis, Defanyl, Demolox, Moxadil), clomipramine (Anafranil), imipramine (Tofranil), desipramine (Norpramin, Pertofrane), dothiepin hydrochloride (Thaden, Prothiaden), doxepin (Adapin, Sinequan), Iofepramine (Lomont, Gamanil), triimipramine (Surmontil), nortriptyline (Pamelor, Aventyl), and protriptyline (Vivactil).
Amitriptyline inhibits serotonin and noradrenaline reuptake almost equally. It is approved for the treatment of endogenous depression, involutional melancholia, and reactive depression. Amoxapine mainly inhibits the reuptake of norepinephrine.