Mood alteration following oral and intravenous haloperidol and relationship to drug concentration in normal subjects.

Haloperidol was administered to 12 subjects intravenously (0.125 mg/kg) and to nine subjects orally (0.5 mg/kg). These doses produced sedation in most subjects. A minimal decrease in orthostatic blood pressure was observed. Administration of the Profile of Mood States to these subjects revealed effects on factor 4, vigor-activity, and factor 6, confusion-bewilderment, but many subjects could not complete testing due to excessive sedation. Haloperidol concentrations were obtained during testing and correlated moderately with scores of these subscales. Correlation was also noted between haloperidol concentration and chlorpromazine effect as measured by the Addiction Research Center Inventory. Extrapyramidal reactions, mainly acute dystonic reactions and akathisia, were common. Dystonia occurred in four subjects after intravenous, and three subjects, after oral administration. Akathisia occurred in eight subjects after intravenous, and three subjects after oral administration. Extrapyramidal reactions tended to occur relatively early or relatively late, at times when drug concentrations were far less than peak values.