Serum concentrations and side effects in psychiatric patients during risperidone therapy

Ther Drug Monit. 1998 Aug;20(4):380-4. doi: 10.1097/00007691-199808000-00004.


Steady state serum concentrations of risperidone and 9-hydroxyrisperidone (9-OH-risperidone), the active moiety, were measured in 42 patients. The concentration-to-dose ratios (C/D) varied by a factor of 20, from 1.8 to 36.8 (nmol/l)/(mg/24 hours), and 90% of the active moiety was constituted of 9-OH-risperidone. No correlation between the serum concentration of the active moiety and the side effects evaluated by the UKU Side Effect Scale was found. The absence of CYP2D6 (poor metabolizers) or the coadministration of drugs other than benzodiazepines increased the ratio between parent compound and metabolite but did not significantly influence the C/D of the total active moiety. A therapeutic range for serum risperidone has not been established, but 6 mg/day is considered the optimum dose for most patients. The authors found that in 90% of 22 patients administered 6 mg/day risperidone, the serum levels were within 50 to 150 nmol/l.

Publication types

  • Clinical Trial

MeSH terms

  • Adult
  • Aged
  • Antipsychotic Agents / adverse effects*
  • Antipsychotic Agents / blood*
  • Antipsychotic Agents / therapeutic use
  • Cross-Sectional Studies
  • Cytochrome P-450 CYP2D6 / metabolism
  • Drug Interactions
  • Female
  • Genotype
  • Humans
  • Isoxazoles / blood
  • Male
  • Middle Aged
  • Paliperidone Palmitate
  • Psychotropic Drugs / pharmacology
  • Pyrimidines / blood
  • Risperidone / adverse effects*
  • Risperidone / blood*
  • Risperidone / therapeutic use


  • Antipsychotic Agents
  • Isoxazoles
  • Psychotropic Drugs
  • Pyrimidines
  • Cytochrome P-450 CYP2D6
  • Risperidone
  • Paliperidone Palmitate