Table 5.

Receptor affinities for selected antipsychotics (derived from Procyshyn et al. [92] Howard et al. [93], and Lal et al. [94])

Drug	D2 blockadea	5-HT1A blockade	5-HT2A blockade	α1 blockadeb	α2 blockade	H1 blockadec	M1 blockaded
Haloperidol	+++++	+	+++	+++	+	+	+
Levomepromazine (methotrimeprazine)	+++	?	++++	+++++	++	+++++	++
Chlorpromazine	++++	+	++++	++++	++	+++	+++
Olanzapine	+++	+	++++	+++	++	++++	++++
Quetiapine	++	++e	+++	+++	+++	+++	++
Risperidone	++++	++	+++++	++++	++	+++	–
Aripiprazole	+++++e	++++e	++++	+++	+++	+++	–

The lower the K _i value, the higher the receptor affinity

Increased sedation associated with increasing H₁ blockade

5-HT _1A 5-hydroxytryptamine-1A (serotonergic) receptor, 5-HT _2A 5-hydroxytryptamine-2A (serotonergic) receptor, D ₂ dopamine-2 receptor, H ₁ histamine-1 receptor, K _i inhibition constant, M ₁ anticholinergic (muscarinic-1) receptor, α ₁ alpha-1 adrenergic receptor, α ₂ alpha-2 adrenergic receptor, – indicates K _i > 10,000 nM, + indicates K _i 1000–10,000 nM, ++ indicates K _i 100–1000 nM, +++ indicates K _i 10–100 nM, ++++ indicates K _i 1–10 nM, +++++ indicates K _i 0.1–1 nM, ? indicates unknown K _i

^aPharmacological effects of antagonism in nigrostriatal system: extrapyramidal side effects partially mitigated in second-generation (atypical) antipsychotics by 5-HT_2A receptor antagonism

^bPharmacological effects: postural hypotension, dizziness, sedation

^cPharmacological effects: sedation, anxiolytic effects

^dPharmacological effects: moderation of extrapyramidal adverse effects; anticholinergic effects: blurred vision, dry mouth, constipation, etc

^ePartial agonist