title: Sequential changes in the plasma concentration of risperidone following intentional overdose.
abstract: Risperidone (RIS) is a novel antipsychotic agent whose pharmacokinetics have yet to be fully determined. In particular, little is known about RIS following an overdose. We report the pharmacokinetics following ingestion of a high dose of RIS by serially measuring the plasma concentration in two patients. These patients were admitted in a comatose state following an intentional overdose of RIS; all patients survived. In the first patient, 14 mg of RIS had been ingested 2 hr before the first blood sample was obtained. The second patient ingested an estimated 90 mg of RIS. Seven time-points were determined. The maximum concentration of unaltered RIS was 325 ng/mL and that of the principal metabolite (9-hydroxy-risperidone: 9-OH RIS) was 139 ng/mL. By plotting the time-concentration curve for the active fraction (RIS plus 9-OH-RIS) in the first and second patients, the half-life of RIS following overdose was determined and was approximately 12.7 hr and 17.8 hr, respectively. These values are similar to the half-life of RIS in healthy individuals ingesting a therapeutic dose. Two patients did not developed parkinsonism nor dystonia, and were discharged without sequelae.
authors.affiliation: Department of Kidney and Dialysis, Hyogo College of Medicine, Nishinomiya, Japan. h-nskg@hyo-med.ac.jp
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Nishikage
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takamitsu
authors.forename: Junnosuke
authors.initials: J
authors.lastname: Yamamoto
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000097:blood* / Q000627:therapeutic use; D003128:Coma / Q000097:blood / Q000150:complications / Q000188:drug therapy; D004305:Dose-Response Relationship, Drug; D062787:Drug Overdose / Q000097:blood*; D005260:Female; D006801:Humans; D007555:Isoxazoles / Q000097:blood; D008875:Middle Aged; D000068882:Paliperidone Palmitate; D011743:Pyrimidines / Q000097:blood; D018967:Risperidone / Q000009:adverse effects / Q000097:blood* / Q000627:therapeutic use; D012559:Schizophrenia / Q000097:blood* / Q000150:complications / Q000188:drug therapy; D013997:Time Factors
chemical_list: D014150:Antipsychotic Agents; D007555:Isoxazoles; D011743:Pyrimidines; D018967:Risperidone; D000068882:Paliperidone Palmitate