Typical antipsychotics

The primary pharmacological effect of typical antipsychotic drugs is achieved though the antagonistic action at dopamine receptors. The therapeutic potency of the antipsychotic drugs correlates to some extent with the affinity for the D2 receptor. The main indication for typical agents are to reduce positive symptoms. However, the typical agents are not selective for any of the four dopamine pathways in the brain and therefore are related with a wide range and high incidence of side effects.

Types of typical antipsychotic drugs​


Phenothiazines: act as antagonists not only at dopamine receptors but at various other receptors which include α1- adrenoceptors, histamine H1 receptors and muscarinic cholinergic receptors. Phenothiazines can be classed into three main groups. 
        1. Aminoalkyl compounds: chlorpromazine, promazine and  levomepromazine produce moderate antimuscarinic and extrapyramidal side effects, and marked sedation.
        2. Piperidine compounds: pipotiazine and pericyazine produce moderate sedation and  have a low incidence of extrapyramidal side effects.
        3. Piperazine compounds: Trifluoperazine, perphenazine and fluphenazine have fewer antimuscarinic and sedating properties, however they most frequently produce pronounced extrapyramidal side effects.

Butyrophenones: consist of haloperidol and benperidol, which are clinically similar to the piperazine compounds.

Thioxanthenes include zuclopentixol and flupentixol which produce moderate antimuscarinic, sedative, and extrapyramidal side effects.

Substituted benzamides (sulpiride) and the diphenylbutylpiperidines (pimozide) both produce reduced antimuscarinic, sedative and extrapyramidal side effects.