The article by Volavka et al1 in the October 1995 issue of the Archives supports the existence of an upper limit of haloperidol plasma concentrations of approximately 12 ng/mL for the treatment of patients with acutely exacerbated schizophrenia.
Volavka et al1 do not report a clear lower limit for the antipsychotic activity of plasma concentrations of haloperidol. The authors suggest that a "continuous increase of antipsychotic activity from levels close to 0 to approximately 12 ng/mL" exists.1 However, the definition of a minimum haloperidol plasma concentration for a meaningfulantipsychotic effect may have clinical relevance. The reanalysis of their data using the lower limit found in our study2 showed that while only 54.8% of the patients with plasma concentrations less than 5.5 ng/mL were considered improved, the value for patients with concentra
Palao DJ, Araùxo A, Haro JM, Brunet M, Bernardo M. The Relationship Between Plasma Haloperidol Concentrations and Clinical Results. Arch Gen Psychiatry. 1996;53(12):1167-1168. doi:10.1001/archpsyc.1996.01830120107019