High levels of dopamine D2 receptor occupancy with low-dose haloperidol treatment: a PET study

Am J Psychiatry. 1996 Jul;153(7):948-50. doi: 10.1176/ajp.153.7.948.


Objective: The purpose of this study was to determine the dopamine D2 receptor occupancy induced by low-dose haloperidol treatment in a prospective trial.

Method: Seven patients with schizophrenia were treated with 2 mg/day of haloperidol for 2 weeks, and D2 receptor occupancy was measured by [11C]raclopride and positron emission tomography.

Results: The patients showed high levels of D2 occupancy (53%-74%); five of them showed substantial clinical improvement, and none showed important side effects.

Conclusions: The findings demonstrate that low doses of haloperidol induce D2 receptor occupancies that are in the putative therapeutic range. In combination with recent empirical trials, these findings should encourage clinicians to initiate treatment of psychotic episodes with low (2-4 mg haloperidol equivalent) doses of typical neuroleptics, particularly for first-episode patients.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Brain / diagnostic imaging*
  • Brain / drug effects
  • Brain / metabolism
  • Carbon Radioisotopes
  • Dose-Response Relationship, Drug
  • Female
  • Haloperidol / administration & dosage*
  • Haloperidol / pharmacokinetics*
  • Haloperidol / pharmacology
  • Humans
  • Male
  • Prospective Studies
  • Psychiatric Status Rating Scales
  • Raclopride
  • Receptors, Dopamine D2 / drug effects
  • Receptors, Dopamine D2 / metabolism*
  • Salicylamides
  • Schizophrenia / drug therapy*
  • Schizophrenia / metabolism
  • Schizophrenic Psychology
  • Tomography, Emission-Computed*


  • Carbon Radioisotopes
  • Receptors, Dopamine D2
  • Salicylamides
  • Raclopride
  • Haloperidol