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 .
There are no well controlled studies with Haldol (haloperidol) in pregnant women. There are reports, however, of cases of limb malformations observed following maternal use of Haldol along with other drugs which have suspected teratogenic potential during the first trimester of pregnancy. Causal relationships were not established in these cases. Since such experience does not exclude the possibility of fetal damage due to Haldol, this drug should be used during pregnancy or in women likely to become pregnant only if the benefit clearly justifies a potential risk to the fetus.