Haloperidol chemical structure

Because of multiple receptor actions, which occur at different concentrations, different neuroleptics have different action profiles. There are many classifications for neuroleptic drugs, the least useful of which is probably based on their chemical structure. Other classifications include linear classifications based on the propensity to cause EPS, or multidimensional ones such as the Liege star which combines information on three positive effects (anti-autistic, antiproductive, antipsychotic), and three negative (hypotensive, extrapyramidal, sedative). In a general way, the more sedative neuroleptics such as levomepromazine, used more to treat acute agitation states, cause more hypotension related to alpha blockade, whereas those that act best on delirium (productive states) such as haloperidol tend to cause more EPS. 

Fig. 13.1 Chemical structure of clozapine, some of its structural analogues, typical (chlorpromazine, haloperidol) and atypical antipsychotics (risperidone, ziprasidone, sertindole and amisulpride) unrelated to clozapine.

Chart 1.9 Chemical structures of chlorpromazine (20), reserpine (21), haloperidol (22). 

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