Prolactin levels in male schizophrenic patients treated with risperidone and haloperidol: a double-blind and randomized study.
BACKGROUND
There are few data from systematic, double-blind clinical trials that have compared the effect of the typical and the atypical antipsychotics on serum prolactin (PRL) levels in patients with schizophrenia.


OBJECTIVE
The goal of this study was to compare the effect of risperidone and haloperidol on serum PRL and investigate the relationship between serum PRL levels and clinical response in patients with schizophrenia.


METHODS
Seventy-eight inpatients with a diagnosis of schizophrenia (according to DSM-III-R) were randomly assigned to 12 weeks of treatment with 6 mg/day of risperidone or 20 mg/day of haloperidol after a 2-week washout period, using a randomized, double-blind design. Clinical efficacy was determined using the positive and negative syndrome scale (PANSS). Their serum PRL was assayed by means of radioimmunometric assay (RIA) between pre-treatment and post-treatment, and compared with 30 sex-matched and age-matched normal subjects.


RESULTS
Both risperidone and haloperidol treatment significantly increased serum PRL levels in drug-free chronic schizophrenia patients (both P<0.001). Hyperprolactinemia induced by risperidone 6 mg/kg was comparable to levels produced by haloperidol 20 mg/day. Considering dose-adjusted serum PRL levels, risperidone treatment induced a significant elevation of PRL levels compared with haloperidol treatment at the haloperidol equivalent (P<0.001). Change in PRL levels at pre-treatment and post-treatment were related to positive symptom improvement seen in the risperidone group (r=0.51, P=0.016), but not in the haloperidol group (P>0.05). Female patients showed both a higher baseline and post-treatment PRL level and a greater increase in PRL than men (all P<0.05).


CONCLUSIONS
Risperidone is associated with a robust effect on prolactin secretion in contrast to the conventional antipsychotic haloperidol. Prolactin monitoring during risperidone treatment should be performed.
Institute of Mental Health, Peking University, Beijing, People's Republic of China. zhangxy9@yahoo.com
Xiang Yang
XY
Zhang
Dong Feng
DF
Zhou
Lian Yuan
LY
Cao
Pei Yan
PY
Zhang
Gui Ying
GY
Wu
Yu Cun
YC
Shen
D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects*; D004311:Double-Blind Method; D005260:Female; D006220:Haloperidol / Q000009:adverse effects*; D006801:Humans; D006966:Hyperprolactinemia / Q000139:chemically induced; D008297:Male; D011388:Prolactin / Q000097:blood* / Q000378:metabolism; D011863:Radioimmunoassay; D018967:Risperidone / Q000009:adverse effects*; D012559:Schizophrenia / Q000188:drug therapy*
D014150:Antipsychotic Agents; D011388:Prolactin; D006220:Haloperidol; D018967:Risperidone