Pharmacokinetics of risperidone in chronic schizophrenic patients.
In a randomized, crossover study, 24 schizophrenic patients received a single 4-mg dose of risperidone in caplet or tablet form. Each of the two study periods lasted 5 days. Blood samples to determine (by radioimmunoassay) plasma levels of risperidone and its major metabolite, 9-hydroxy-risperidone (9-OH-risperidone), were obtained each day. The two formulations of risperidone were bioequivalent. Following are the mean pharmacokinetics of risperidone and risperidone + 9-OH-risperidone: area under the plasma concentration curve (AUC) from 0 to 96 hours; 278.0 and 716.9 ng.hr/mL; AUC from 0 to infinity, 291.9 and 762.4 ng.hr/mL; peak plasma concentration, 33.0 and 44.5 ng/mL; time to peak concentration, 1.39 and 1.78 hours; and elimination half-life, 14.93 and 23.04 hours. These results demonstrate that the active moiety (risperidone plus 9-OH-risperidone) has a half-life of 23 hours and reveal a pool of risperidone (terminal half-life, 14.9 hours) that may allow twice-daily or even once-daily dosing.
Borison
R L
RL
Department of Psychiatry Medical College of Georgia, Augusta 30912-3800.
Diamond
B
B
Pathiraja
A
A
Meibach
R C
RC
D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D002908:Chronic Disease; D018592:Cross-Over Studies; D006801:Humans; D007555:Isoxazoles / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010880:Piperidines / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D018967:Risperidone; D012559:Schizophrenia / Q000188:drug therapy / Q000378:metabolism*; D013810:Therapeutic Equivalency
D014150:Antipsychotic Agents; D007555:Isoxazoles; D010880:Piperidines; D018967:Risperidone