Introduction: Conventional antipsychotic medications are associated with elevated prolactin levels, resulting in hyperprolactinemia and a number of unwanted side effects. Several atypical antipsychotics, on the other hand, are less likely to evoke hyperprolactinemia. The aim of this study was to investigate the prevalence of hyperprolactinemia induced by conventional antipsychotic drugs, examine changes in serum prolactin levels and psychiatric symptoms after switching to quetiapine, and identify the relevant characteristics of patients who may be suitable to switch to quetiapine.
Method: Sixty-nine of 74 consecutive female patients who had received conventional antipsychotic drugs were initially included in the study. Of these, 49 (71 %) patients suffered from hyperprolactinemia, of which a further 25 were subsequently switched to quetiapine. Psychiatric symptoms were assessed by the Positive and Negative Syndrome Scale (PANSS), and serum prolactin levels were measured just before and at 4 and 8 weeks after switching.
Results: Eight of the 25 (32 %) "switch" patients dropped out due to psychotic exacerbation during the 8 weeks. In the remaining 17 (68 %) patients, serum prolactin levels were significantly decreased without any significant change in PANSS scores after switching. The 17 patients who completed the switch had previously demonstrated significantly lower positive symptom scores compared to the 8 dropout patients.
Conclusion: The present findings suggest that 71 % of female patients receiving conventional antipsychotic drugs may suffer from hyperprolactinemia and that approximately two-thirds of patients can be switched to quetiapine, resulting in an improvement in hyperprolactinemia. The main characteristic of the switched patients may be fewer positive symptoms.