In the present study, we aimed to determine the pharmacokinetics (PK), pharmacodynamics (PD), adverse events (AEs), and their relationships in Chinese patients with schizophrenia after a single dose of long-acting risperidone. Schizophrenic patients (six females and seven males) were enrolled in this study. Serial blood samples were collected after drug administration during 63 d, and the drug concentrations were analyzed by LC-MS/MS. Safety and tolerance were evaluated by monitoring the AEs, changes in clinical laboratory results, 12-lead ECG, vital signs, physical examination, and injection-site reactions. The extrapyramidal symptoms were evaluated using the ESRS. Efficacy was evaluated by the PANSS and BPRS. Twelve out of the 13 participants completed the trial. There were few clinically meaningful changes in mean clinical laboratory values, vital signs, or ECG parameters, except for the prolactin level and body weight. There were no serious AEs, and those observed were reversible. Significant clinical improvements in PANSS and PANSS-derived BPRS total scores were observed. The mean (standard deviation, coefficient of variation) values for these PK parameters were as follows: Cmax, 8.954 (8.059, 90.0%) ng/mL; area under the curve AUC0–t, 2453 (1156, 47.1%) ng?h/mL; AUC0–∞, 2472 (1160, 46.9%) ng?h/mL; tmax, 830.0 (min: 744.0, max: 984.0, 11.8%) h; and t1/2, 68.56 (10.77, 15.7%) h. The PK characteristics of long-acting risperidone showed a high level of inter-individual variation, while there were no clear correlations between PK, efficacy and AEs among the patients in the present study.
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