[Atypical neuroleptics, pharmacology and clinical importance]

Since the development of clozapine the investigation of atypical neuroleptic compounds has become increasingly relevant. Compared with classic neuroleptics they are distinguished by either fewer or absent (clozapine) extrapyramidal side effects, some of them also by lower increases of serum prolactin concentrations. Pharmacologically they are a group of heterogeneous substances. At the level of transmitter systems a high 5HT2/D2-ratio is regarded as the best criterion to distinguish between atypical and classic neuroleptics. Further differences involve: the preferred effects of atypical neuroleptics on mesolimbic D2 receptors compared to striatal dopaminergic neurotransmission; a higher potency of some atypical neuroleptics to antagonize D1-receptors; the increase of serum corticosterone concentrations by some of the atypical neuroleptics.