Gonadal axis hormones in male schizophrenic patients during treatment with haloperidol and after switch to risperidone.

RATIONALE

The atypical neuroleptic risperidone, in addition to its dopamine receptor blocking activity, has a high affinity for serotonergic receptors. Since both dopaminergic and serotonergic neuronal activities participate in regulation of the pituitary gonadal axis (PGA), it is expected that a switch from treatment with haloperidol to treatment with risperidone should influence plasma levels of PGA hormones.

OBJECTIVE

To study the effects of a drug with dopamine and serotonin receptor blocking activity on PGA hormones in patients who were on treatment with a dopamine receptor blocker.

METHODS

Plasma levels of testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH), as well as prolactin and cortisol, were measured in 16 male schizophrenic patients during treatment with haloperidol (mean dose 23.3 mg daily, SD = 16.9) and 6 weeks later after switching to treatment with risperidone (mean dose 11.8 mg daily, SD = 2.9). Psychopathology was assessed by BPRS.

RESULTS

After switching to risperidone, total BPRS score and the scores in its subscales for positive, negative, and general symptoms were all significantly reduced in the order of 35-45%. Prolactin levels were significantly increased from 39.5+/-22.3 to 58.9+/-28.5 ng/ml (F= 4.61, P = 0.04), while cortisol, testosterone, LH, and FSH remained unchanged. No significant correlations between prolactin increases and reduction in BPRS or in its subscale scores were found.

CONCLUSIONS

The results show that blocking of both dopamine and serotonin receptors does not influence the pituitary gonadal axis but considerably increases prolactin release.