Pharmacopsychiatry 2002; 35(6): 231-234
DOI: 10.1055/s-2002-36389
Original Paper
© Georg Thieme Verlag Stuttgart · New York

Relationship between Risperidone and 9-hydroxy-risperidone Plasma Concentrations and CYP2D6 Enzyme Activity in Psychiatric Patients

R. Berecz1, 2 , A. LLerena1 , A. de la Rubia1 , J. Gómez1 , M. Kellermann2 , P. Dorado1 , I. Degrell2
  • 1University of Extremadura, Faculty of Medicine, Department of Pharmacology and Psychiatry, Unit of Research and Clinical Psychopharmacology, Mérida Psychiatric Hospital, Badajoz, Spain
  • 2University of Debrecen, Medical and Health Science Center, Department of Psychiatry, Debrecen, Hungary
Further Information

Publication History

Received: 8. 3. 2001 Revised: 25. 2. 2002

Accepted: 8. 3. 2002

Publication Date:
20 December 2002 (online)

The implication of cytochrome P450 CYP2D6 enzyme activity in the metabolism of the antipsychotic drug risperidone has been reported in vitro and in studies of healthy volunteers. Around 7 % of Caucasians have inherited impaired capacity of this enzyme (poor metabolisers). These subjects might be prone to higher plasma concentrations of risperidone. The aim of the study was to determine the relationship between the debrisoquine metabolic ratio (MR), a marker of CYP2D6 enzyme activity, and risperidone plasma levels in psychiatric patients.

A population of 40 Spanish and Hungarian schizophrenic patients was studied. The possible inhibition of CYP2D6 enzyme was also evaluated in a subgroup of patients co-medicated with inhibitors of CYP2D6. The risperidone/9-hydroxy-risperidone ratio correlated significantly with debrisoquine MR (p < 0.001). In patients co-medicated with strong inhibitors of CYP2D6, the plasma levels of risperidone (p < 0.05) and debrisoquine MR (p < 0.01) and risperidone/9-hydroxy-risperidone ratio were higher compared to patients with monotherapy. According to the present data, the evaluation of the risperidone/9-hydroxy-risperidone ratio may reflect the actual enzyme activity of CYP2D6. Therefore, the use of this ratio may help to assess potential pharmacokinetic interactions and to improve risperidone treatment.

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Dr. Adrián Llerena

University of Extremadura

Faculty of Medicine

Department of Pharmacology and Psychiatry. Avda. de Elvas s/n.

E-06071

Badajoz

Spain

Phone: 34 924289467

Fax: 34 924289467

Email: allerena@unex.es

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