Given these considerations, antipsychotic drugs should be prescribed in a manner that is most likely to minimize the occurrence of tardive dyskinesia. Chronic antipsychotic treatment should generally be reserved for patients who suffer from a chronic illness that 1) is known to respond to antipsychotic drugs, and 2) for whom alternative, equally effective, but potentially less harmful treatments are not available or appropriate. In patients who do require chronic treatment, the smallest dose and the shortest duration of treatment producing a satisfactory clinical response should be sought. The need for continued treatment should be reassessed periodically.
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 .
Clozapine, olanzapine and, to a lesser extent, quetiapine may cause sedation, anticholinergic effects and orthostatic hypotension. Quetiapine has not been studied in the elderly. 18 How this drug compares with other newer antipsychotics remains to be established. 19 Risperidone is well tolerated, 18 and several studies have demonstrated its efficacy in the management of psychotic and aggressive symptoms in patients with dementia. 18 , 20 Risperidone, in dosages of to mg per day, has successfully alleviated behavioral disturbances in patients with Alzheimer's disease. 21 , 22 Clozapine is somewhat more difficult to use because of its association with agranulocytosis and the need for periodic monitoring of complete blood counts.