Atypical antidepressant drugs - psychopharmacological profile and mechanism of action.

The psychopharmacological profile and mechanism of action of ten atypical novel and potential antidepressive drugs (AD) have been investigated. It has been shown that they form a pharmacologically heterogeneous group. Some of them may be considered as central 5-hydroxytryptamine (5-HT) antagonists. Two typical AD, amitriptyline and doxeprine, turned out to be potent 5-HT antagonists also. These observations justify the conclusion that these drugs rather block than facilitate 5-HT neurotransmission. Some data indicate that 5-HT antagonists can shift the balance between the noradrenergic and serotoninergic systems in favour of the former. Both atypical and typical AD when administered chronically, induce effects not observed after single-dose treatment. The effects observed indicate that the chronic administration of AD leads to the development of the increased responsiveness (or activation) of the noradrenergic system.