A comparison of serum prolactin concentrations after administration of paliperidone extended-release and risperidone tablets in patients with schizophrenia

Increases in serum prolactin concentrations after administration of risperidone have been attributed, by some, to the availability of paliperidone in plasma. This double-blind, randomized, parallel-group study in patients with schizophrenia compared serum prolactin concentrations following the administration of paliperidone extended-release and risperidone immediate-release tablets. At steady state, the doses administered resulted in a similar exposure to paliperidone and the pharmacologically active fraction of risperidone (i.e. risperidone + paliperidone), respectively. Eligible patients were randomized to either paliperidone extended-release 12 mg on days 1—6 or risperidone immediate-release 2 mg on day 1 and 4 mg on days 2—6. Mean serum prolactin concentrations increased on day 1 (Cmax: 71.8 ng/ml and 89.7 ng/ml reached at 6.5 hours and 2.6 hours for paliperidone extended-release and risperidone immediate-release, respectively). On day 6, serum prolactin concentration—time profiles were similar for bo...