Plasma haloperidol levels drawn at neuroleptic threshold doses: A pilot study

Joseph P. McEvoy, Richard L. Stiller, Pussell Farr

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


The daily haloperidol doses of 33 newly admitted, acutely psychotic schizophrenic patients were rapidly adjusted to a point at which slight hypokinesia–rigidity first appeared on clinical examination (the neuroleptic threshold). The mean daily haloperidol dose at which the neuroleptic threshold was crossed was 4.2 ± 2.4 mg/day. The plasma haloperidol levels obtained at these neuroleptic threshold doses clustered around a mean of 4.9 ± 2.9 ng/ml. This plasma haloperidol level distribution extensively overlaps the proposed lower boundaries for the therapeutically effective range of plasma haloperidol levels, but it is below the range in which coarse extrapyramidal side effects appear in high frequency (>10 ng/ml). Sixty–seven percent of our patients demonstrated moderate or greater therapeutic improvement within 3 weeks of treatment at neuroleptic thresh-old doses, a therapeutic efficacy rate identical to that expected with standard neuroleptic doses. The authors propose that the neuroleptic threshold is a readily available clinical marker which identifies a range of plasma haloperidol levels cpable of producing therapeutic response with minimal associated coarse extrapyramidal side effects.

Original languageEnglish (US)
Pages (from-to)133-138
Number of pages6
JournalJournal of Clinical Psychopharmacology
Issue number3
StatePublished - Jan 1 1986
Externally publishedYes

ASJC Scopus subject areas

  • Psychiatry and Mental health
  • Pharmacology (medical)


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