title: Lack of effect of amitriptyline on risperidone pharmacokinetics in schizophrenic patients.
abstract: The interaction between plasma concentrations of the tricyclic antidepressant amitriptyline and the metabolism of the new antipsychotic risperidone was studied in 12 patients with chronic schizophrenia. Each patient received 3 mg risperidone twice a day for 28 days. Amitriptyline was coadministered at doses of 50 mg/day on day 15 and 100 mg/day on days 16 to 21. Amitriptyline did not significantly affect the mean plasma concentrations or pharmacokinetics of risperidone in schizophrenic patients or influence the antipsychotic fraction (the total concentration of risperidone and 9-hydroxyrisperidone, its primary and biologically active metabolite). These results suggest that risperidone dose need not be adjusted when coadministered with amitriptyline at doses up to 100 mg/day in schizophrenic patients.
authors.affiliation: Department of Pharmacology, University of Pretoria, South Africa.
authors.forename: D K
authors.initials: DK
authors.lastname: Sommers
authors.forename: J R
authors.initials: JR
authors.lastname: Snyman
authors.forename: M
authors.initials: M
authors.lastname: van Wyk
authors.forename: M W
authors.initials: MW
authors.lastname: Blom
authors.forename: M L
authors.initials: ML
authors.lastname: Huang
authors.forename: J C
authors.initials: JC
authors.lastname: Levron
mesh_terms: D000328:Adult; D000639:Amitriptyline / Q000009:adverse effects*; D000929:Antidepressive Agents, Tricyclic / Q000009:adverse effects*; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001711:Biotransformation; D003692:Delayed-Action Preparations; D004347:Drug Interactions; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D018967:Risperidone / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012559:Schizophrenia / Q000378:metabolism*
chemical_list: D000929:Antidepressive Agents, Tricyclic; D014150:Antipsychotic Agents; D003692:Delayed-Action Preparations; D000639:Amitriptyline; D018967:Risperidone