Risperidone (and 9-hydroxyrisperidone)

Risperidone and 9-hydroxyrisperidone by LC-MS/MS.
Clinical details: 
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®). 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.
Sample type and Volume required: 
2mL of EDTA whole blood preferred. Serum or plasma can be used if required.
Turnaround time: 
5 working days.
Storage and transport: 
Please refrigerate (if possible) if not sending immediately. Send by first class post.
Toxicology Department at King's Hospital
020 3299 5881
King's College Hospital
Bessemer Wing - 3rd Floor
Denmark Hill
London SE5 9RS
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 03/10/2022