RISPERIDONE AND METABOLITE QUANTITATION
- RISPERIDONE AND METABOLITE QUANTITATION
- Start Date
- Expiration Date
- Risperdal®, Risperidone Metabolite, Total Active Moiety
- CPT Codes
- Reference Test
- ATLAS Test Code
- Transport Info
Centrifuge and immediately transfer serum to separate plastic tube
- Fasting Required?
- Patient Instructions
- Reference Range
High Performance Liquid Chromatography/Tandem Mass Spectrometry (LC-MS/MS)
Therapeutic Drug Monitoring/Antipsychotic (Neuroleptic)
Risperidone (Risperdal) is a relatively unique antipsychotic drug of the benzisoxazole class that is used in the management of the manifestations of schizophrenia. Its activity is thought to be mediated through the antagonism of a combination of dopamine type 2 (D2) and serotonin type 2 (5HT2) receptors. The efficacy of antipsychotic activity was established in short-term (6-8 weeks) controlled trials. A physician who counsels patients to use risperidone for longer periods of time is advised to periodically re-evaluate the long-term usefulness for each individual patient. THERAPEUTIC MONITORING: Among other products, biotransformation in the liver produces 9-hydroxyrisperidone, which is of the same pharmacological activity and intensity as parent risperidone. For this reason, it is important to add the measurement of risperidone and 9-hydroxyrisperidone together when monitoring the antischizophrenic therapy of risperidone administration. The apparent half-life of risperidone is 3 hours, and for 9-hydroxyrisperidone it is 21 hours. Steady state for risperidone is usually reached in one day and in 5-6 days for the metabolite. The concentrations of risperidone plus 9-hydroxyrisperidone are dose-proportional with the dosing range of 1-16 mg per day. Following oral administration, mean peak plasma concentrations of risperidone and 9- hydroxyrisperidone occur at ca. 1 and 3 hours, respectively.