Messanae Universitas Studiorum

Effect of fluvoxamine on plasma risperidone concentrations in patients with schizophrenia

D'Arrigo, Concetta and Migliardi, Gaetana and Santoro, Vincenza and Morgante, Letterio and Muscatello, Maria R. A. and Ancione, Maria and Spina, Edoardo (2005) Effect of fluvoxamine on plasma risperidone concentrations in patients with schizophrenia. Pharmacological Research, 52 (6). pp. 497-501. ISSN 1043-6618


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The effect of fluvoxamine on plasma concentrations of risperidone and its active metabolite 9-hydroxyrisperidone (9-OH-risperidone) was investigated in 11 schizophrenic patients with prevailingly negative or depressive symptoms. Additional fluvoxamine, at the dose of 100 mg/day, was administered for 4 weeks to patients stabilized on risperidone (3–6 mg/day). Mean plasma concentrations of risperidone, 9-OH-risperidone and the active moiety (sum of the concentrations of risperidone and 9-OH-risperidone) were not significantly modified following co-administration with fluvoxamine. After 4 weeks, fluvoxamine dosage was increased to 200 mg/day in five patients and then maintained until the end of week 8. At final evaluation, mean plasma levels of risperidone active moiety were not modified in the six patients who were still receiving the initial fluvoxamine dose, while concentrations increased slightly but significantly (by a mean 26% over pretreatment; P < 0.05) in the subgroup of five subjects treated with a final dose of 200 mg/day. Fluvoxamine co-administration with risperidone was well tolerated and no patient developed extrapyramidal side effects. These findings indicate that fluvoxamine at dosages up to 100 mg/day is not associated with clinically significant changes in plasma risperidone concentrations. However, higher doses of fluvoxamine may elevate plasma risperidone levels, presumably as a result of a dose-dependent inhibitory effect of fluvoxamine on CYP2D6-and/or CYP3A4-mediated 9-hydroxylation of risperidone.

Item Type: Article
Uncontrolled Keywords: Risperidone; 9-Hydroxyrisperidone; Fluvoxamine; Drug interaction; CYP2D6; CYP3A4
Subjects: M.U.S. - Contributi Scientifici > 06 - Scienze mediche
Depositing User: Mr Nunzio Femminò
Date Deposited: 08 Oct 2009
Last Modified: 22 Jan 2013 09:38

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