The oldest depots available were haloperidol and fluphenazine , with flupentixol and zuclopenthixol as more recent additions. All have a similar, predominantly extrapyramidal, side effect profile though there are some variations between patients. More recently, long acting preparations of the atypical antipsychotic, risperidone , and its metabolite paliperidone , have become available thus offering new choices. However, Risperidone tends to have a higher incidence of extrapyramidal effects when compared to the tricyclic and tetracyclic atypical antipsychotics, such as quetiapine , clozapine , olanzapine , etc. [ citation needed ]
Haloperidol is a typical butyrophenone type antipsychotic that exhibits high affinity dopamine D 2 receptor antagonism and slow receptor dissociation kinetics.  It has effects similar to the phenothiazines .  The drug binds preferentially to D 2 and α 1 receptors at low dose (ED 50 = and mg/kg, respectively), and 5-HT 2 receptors at a higher dose (ED 50 = mg/kg). Given that antagonism of D 2 receptors is more beneficial on the positive symptoms of schizophrenia and antagonism of 5-HT 2 receptors on the negative symptoms, this characteristic underlies haloperidol's greater effect on delusions, hallucinations and other manifestations of psychosis.  Haloperidol's negligible affinity for histamine H 1 receptors and muscarinic M 1 acetylcholine receptors yields an antipsychotic with a lower incidence of sedation, weight gain, and orthostatic hypotension though having higher rates of treatment emergent extrapyramidal symptoms .