Antidepressants. A comparative review of the clinical pharmacology and therapeutic use of the 'newer' versus the 'older' drugs.

Supplementing but not supplanting the original series of tricyclic and monoamine oxidase (MAO) inhibitor compounds, a new generation of antidepressant medications has been developed and marketed throughout the past decade. Constituting a more diverse group of drugs than the standard agents, the newer drugs in general have more selective acute biochemical actions (reuptake blockade of a single neurotransmitter, inhibition of 1 subtype of MAO), enabling more precise targeting of symptoms and avoiding common antidepressant-associated side effects, especially anticholinergic and cardiovascular effects. Moreover, a number of recent additions to this group, such as bupropion and ademetionine (S-adenosyl-methionine), incorporate novel mechanisms of action, challenging previous concepts of how antidepressants work, and offering opportunities for research into the pathophysiology of mood disorders. Caution in prescribing the newer antidepressants must be applied, however, as recent experience, e.g. with nomifensine, suggests that unforeseen toxicities may not appear until a medication has been in use for several years.