Prolactin related symptoms during risperidone maintenance treatment: results from a prospective, multicenter study of schizophrenia

BACKGROUND: This study aimed to investigate prolactin related symptoms (PRS) in individuals with schizophrenia during risperidone maintenance treatment for one year, as well as to identify the risk factors for PRS. METHODS: In a multicenter, randomized, controlled, longitudinal study, clinically stabilized schizophrenia patients (N = 374) were randomized to a no-dose-reduction group (N = 129) and 4-week (N = 125) and 26-week (N = 120) reduction groups, in which the original dose was followed by a 50 % reduction over 8 weeks and subsequently maintained. PRS were assessed via a scale of prolactin related adverse events, which included 16 items: menstrual cycle, menstrual period, menstrual volume, menstrual irregularities, amenorrhea, dysmenorrhea, postpartum lactation, gynecomastia, breast tenderness, sexual dysfunction, decreased sexual desire, erectile dysfunction, ejaculatory dysfunction, impotence, increased body hair, and acne. The occurrence of PRS was assessed at baseline and monthly for six months, followed by every two months. A mixed model was used. RESULTS: PRS at baseline were reported in 18.4, 15.0, and 14.0 % of the 4-week, 26-week, and no-dose-reduction groups, respectively. Female gender, younger age at onset, and the Positive and Negative Syndrome Scale (PANSS) total scores at entry predicted the development of PRS. The mixed model indicated that PRS were more severe in females and at a high dose. In the 237 patients who remained in the study after one year, the incidence of PRS decreased to 9.6, 11.1, and 7.6 % in the 4-week, 26-week, and no-dose-reduction groups, respectively. CONCLUSION: These findings indicate that the PRS severity was alleviated during the one year treatment period because of the dose reduction. Attention should focus on the side effects of hyperprolactinemia during long-term treatment, especially with a high dose, females, younger age at onset, and more severe patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00848432. Registered February 19, 2009.