Randomized controlled trial comparing changes in serum prolactin and weight among female patients with first-episode schizophrenia over 12 months of treatment with risperidone or quetiapine

BACKGROUND: Increased serum prolactin and weight gain are common side effects of atypical antipsychotics but few studies have assessed the long-term pattern of these adverse effects. AIM: Compare the effects of risperidone and quetiapine on serum prolactin and weight over 12 months of treatment among female patients with first-episode schizophrenia. METHODS: Eighty female inpatients with first-episode schizophrenia were randomly assigned to receive risperidone (n=40) or quetiapine (n=40) for 12 months. Prolactin concentration, weight and height were measured one day before starting treatment and 1, 3, 6, 9 and 12 months after initiating treatment. Severity of symptoms was assessed at the same time periods using the Positive and Negative Syndrome Scale (PANSS). RESULTS: Thirty-one patients in the risperidone group and 33 patients in the quetiapine group completed the 12 months of treatment. PANSS scores decreased at each follow-up assessment for both groups; the improvement was significantly greater in the risperidone group after 3 months and 6 months of treatment but by the 9th month of treatment the level of improvement in the two groups was similar. In the quetiapine group serum prolactin remained stable throughout the 12 months but in the risperidone group the serum prolactin level increased 3.5- to 5.2-fold over the one-year follow-up. Weight gain was seen in both groups, particularly during the first 3 months of treatment: 62% of the increase in BMI in both groups had occurred by the end of the 3rd month of treatment. No between-group differences in weight changes were observed. The correlation between changes in weight and changes in prolactin levels were weakly positive: r(s)=0.17(p=0.104) in the risperidone group and r=0.07 (p=0.862) in the quetiapine group. CONCLUSIONS: Risperidone and quetiapine had similar efficacy in the first year of treatment of first-episode schizophrenia though risperidone was more rapidly effective. Use of risperidone was associated with chronic hyperprolactinemia but this did not occur with quetiapine. Long-term use of both drugs was associated with sustained weight gain; the timing and magnitude of the weight gain is similar for the two drugs. Weight gain was not strongly related to changes in prolactin levels.