Dose requirement and prolactin elevation of antipsychotics in male and female patients with schizophrenia or related psychoses

Abstract

Aims: The aim of this study was to investigate the prolactin (PRL) secretion and the growth hormone (GH)-insulin-like growth factor I (IGF-I) axis in relation to gender and side-effects and dose of antipsychotic drugs during long-term treatment.

Methods: Forty-seven patients (21 men and 26 women), diagnosed with schizophrenia or related psychoses according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria and treated with different classical antipsychotics, were studied. Prolactin, GH and IGF-I were measured, as well as the serum concentration of the antipsychotics. In addition, body mass index (BMI) was calculated.

Results: The median daily, as well as the median body weight, adjusted daily dose of antipsychotic drugs was twofold higher in male compared with female patients. Antipsychotic-induced hyperprolactinaemia was more frequent and occurred at a lower daily dose of antipsychotics in women. Irrespective of sex, more than half of the patients had elevated BMI. Two patients had a slight increment in IGF-I levels, whereas the GH concentration, as assessed on a single occasion, was normal in all patients.

Conclusions: Patients on long-term antipsychotic therapy, with doses adjusted according to therapeutic efficiency, exhibited hyperprolactinaemia and elevated BMI, but no obvious influence on the GH-IGF-I axis. Furthermore, it appeared that the males required twice the dose of antipsychotic compared with females.

Figures

Figure 1

Prolactin (PRL) levels related to daily reference dose, expressed as chlorpromazine (CPZ) equivalents in 21 men (•) and 26 women (•) on long-term treatment with antipsychotics. Reference value of PRL ≤ 15µg l−1 for men (dashed line), ≤ 19 µg l−1 for women (solid line).

Figure 2

Ratio between prolactin (PRL) level and daily reference dose of antipsychotic drug (expressed as chlorpromazine equivalents) in 21 men and 26 women on long-term treatment. The box plots indicate the median and lower and upper quartiles, and the whiskers show 10th and 90th percentiles. Outliers are also indicated (•).