Clinical efficacy, extrapyramidal symptoms and serum levels: influence of administration schedules and concomitant drugs on serum bromperidol concentrations.

Bromperidol (4 or 12 mg per day) was administered to 18 newly admitted schizophrenics and 29 chronic schizophrenic inpatients once or four times a day and the two dose schedules were compared. The bromperidol levels in the four-times-a-day group were significantly higher than those in the once-a-day group and the daily variation in the serum level of the agent was markedly wider in the latter than in the former patients. The incidence and severity of extrapyramidal symptoms were not significantly different between the two. A clear relationship was not present between the serum levels and the development of extrapyramidal symptoms. The bromperidol serum values were not correlated with the therapeutic response but, at more than 5 ng per ml, there might be a positive correlation between the bromperidol levels and clinical efficacy in the newly admitted schizophrenics. As for concomitant medication, levomepromazine may raise the bromperidol serum level. An anti-parkinson drug failed to depress the bromperidol level.