title: Risperidone metabolic ratio as a biomarker of individual CYP2D6 genotype in schizophrenic patients.
abstract: OBJECTIVE
  The purpose of the present study was to investigate the predictive value of the risperidone metabolic ratio for the individual CYP2D6 genotype.
  
  
  METHODS
  The determination of risperidone, 9-hydroxyrisperidone, and CYP2D6 genotype was performed in 89 schizophrenic patients. The receiver operator characteristic (ROC) method and the area under the ROC curve (AUC) were used to illustrate the predictive value of risperidone metabolic ratio for the individual CYP2D6 genotype. The area under the ROC curve (AUC) was used as a global measure of this predictive value. To evaluate the proposed cutoff levels of >1 and <0.1 to identify individuals with a poor or ultrarapid CYP2D6 genotype the sensitivity, specificity, positive predictive value and negative predictive were calculated.
  
  
  RESULTS
  The area under the ROC curve (AUC) for poor and ultrarapid metabolisers was 0.85 and 0.86, respectively. The sensitivity, specificity, positive predictive value and negative predictive value of a risperidone/9-OH-risperidone ratio >1 to CYP2D6 poor metaboliser genotype were 75 %, 95 %, 60 % and 97 %, respectively. The corresponding measures for a metabolic ratio < 0.1 to predict ultrarapid metabolisers were 80 %, 77 %, 18 % and 98 %.
  
  
  CONCLUSIONS
  A metabolic ratio > 1 or < 0.1 may be a useful therapeutic biomarker to recommend CYP2D6 genetic testing to guide the present or future treatment of patients in need of psychotropic drugs.
authors.affiliation: Karolinska Institutet, Department of Clinical Science and Education at Södersjukhuset, Stockholm, Sweden, Buster.mannheimer@sodersjukhuset.se.
authors.forename: Buster
authors.initials: B
authors.lastname: Mannheimer
authors.forename: Johan
authors.initials: J
authors.lastname: Holm
authors.forename: Larissa
authors.initials: L
authors.lastname: Koukel
authors.forename: Leif
authors.initials: L
authors.lastname: Bertilsson
authors.forename: Urban
authors.initials: U
authors.lastname: Osby
authors.forename: Erik
authors.initials: E
authors.lastname: Eliasson
mesh_terms: D000328:Adult; D000368:Aged; D014150:Antipsychotic Agents / Q000097:blood / Q000378:metabolism* / Q000493:pharmacokinetics / Q000627:therapeutic use; D019540:Area Under Curve; D015415:Biomarkers / Q000378:metabolism*; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D018967:Risperidone / Q000097:blood / Q000378:metabolism* / Q000493:pharmacokinetics / Q000627:therapeutic use; D012559:Schizophrenia / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents; D015415:Biomarkers; D019389:Cytochrome P-450 CYP2D6; D018967:Risperidone