Selective neuroendocrine effects of low-dose haloperidol in normal adult men.

The neuroendocrine effects of haloperidol, usually reported as side effects of this drug when given in antipsychotic doses, have not been systematically investigated. In the present study 5 normal 18-35 yr old males were administered saline and 2 doses of haloperidol (0.25 mg, 0.5 mg im) in a double-blind randomized block design. The anterior pituitary growth hormone (GH), luteinizing hormone (LH), follicle stimulating hormone (FSH), and prolactin (PRL) were measured in blood samples taken every 20 min for several hours. The low doses of haloperidol used have been shown by others to alter the human EEG; in the present Ss these doses produced no objective or subjective clinical effects. There were no drug related changes in GH, LH, or FSH. PRL, however, showed a prompt, statistically significant, dose-related increase in plasma levels, with a return to baseline within 5 hrs. Haloperidol has strong dopamine (DA)-blocking effects, and the hypothalamic inhibitory mechanism for PRL release is believed to be DA mediated. Results suggest that haloperidol may have utility in low doses primarily for its hypothalamic neuroendocrine effects, and that dose-related PRL release may be a useful paradigm for comparing DA-blocking antipsychotic agents in humans. (38 ref) (PsycINFO Database Record (c) 2016 APA, all rights reserved)