Risperidone and 9-hydroxyrisperidone
Toxicology Overview / Directory
Purpose of the test
Risperidone (Risperidal®) is an atypical or ‘second generation’ antipsychotic. Side-effects of risperidone may include somnolence, nausea, dizziness, and anxiety. There is a risk of hypotension at higher doses. Risperidone can be administered either orally, or by intra-muscular injection. Oral dosage is normally 2-6 mg/d (BNF recommended limit). Patients receiving intra-muscular injection are normally given up to 50 mg every two weeks.
Risperidone is metabolised by hydroxylation and N-demethylation. The 9-hydroxylated metabolite, 9-hydroxyrisperidone, is an active metabolite that also accumulates in plasma. Racemic 9-hydroxyrisperidone is itself licensed for the management of schizophrenia (Paliperidone®).
Measurement of plasma risperidone and total 9-hydroxyrisperidone can be useful to (i) assess adherence, (ii) assess adequacy of dosage, and (iii) investigate suspected acute poisoning. The assay may also be beneficial to ensure that intra-muscular injection shows equivalence to oral dosing. Although a target range in therapy has not been established, a steady state reference range of 20-60 µg/L (risperidone + total 9-hydroxyrisperidone) has been suggested (Hiemke et al., 2004).
Sample Requirements
2mL of EDTA whole blood preferred. Serum or plasma can be used if required.
Storage and Transport
Please refrigerate (if possible) if not sending immediately. Send by first class post to:
Toxicology Unit
Top Floor, Bessemer Wing
King’s College Hospital
Denmark Hill
London
SE5 9RS
COMPLETE (details can be completed electronically) & PRINT the request form below and send as a hard copy (DO NOT SEND ELECTRONICALLY) with the sample. This will ensure all relevant information is available and will aid us in processing your test.
PDF Request Form
Download Risperidone And 9-hydroxyrisperidone Request Form
Turnaround Time
Results are available within 3-5 working days of receipt in the laboratory.
Price
Price available on application - please contact adrianturner1@nhs.net. Discounts could be available for significant workloads.
Contacts
Clinical Advice & Interpretation
Dr Bob Flanagan
T: 020 3299 5881
F: 020 3299 5888
Laboratory
T: 020 3299 5883
F: 020 3299 5888
References
Kim B, L S-H, Choi TK, Suh SY, Kim YW, Lee EH. Yook KH, Effectiveness of risperidone long-acting injection in first-episode schizophrenia: In naturalistic setting Progress in Neuro-Psychopharmacology & Biological Psychiatry 2008; 32(5): 1231-1235
Flanagan RJ. Therapeutic Monitoring of Antipsychotic Drugs CPD Clinical Biochemistry 2006; 7(1): 3-18
Hiemke C, Dragicevic A, Gründer G, Hätter S, Sachse J, Vernaleken I, Müller MJ. Therapeutic Monitoring of Antipsychotic Drugs Therapeutic Drug Monitoring 2004; 26(2): 156-160
