Beyond the limits of typical antidepressants.

Trazodone and tricyclics share similar activity towards the core symptoms of depression, whereas their effects on neurohumoral transmission tend to be opposite. This once again casts doubt upon the theories on depression postulated from the study of monoamine oxidase inhibitors and tricyclics. The effects of trazodone and tricyclics on the autonomic nervous system are also different, reflecting, respectively, the alpha-adrenergic blocking activity of the former and the muscarinic-anticholinergic and alpha-adrenergic stimulating properties of the latter. It is stressed that the autonomic changes that accompany depression to some extent overlap those produced by tricyclics, whereas they are generally relieved by trazodone. This drug, therefore, extends the previous limitations of antidepressant treatment.