Olanzapine
Toxicology Overview / Directory
Purpose of the test
The atypical antipsychotic agent olanzapine is structurally similar to clozapine, and is used in the treatment of schizophrenia and related disorders. It has high affinity for dopamine D1, D2, D4, 5HT2A, 5HT2C, 5HT3, alpha1-adrenergic, histamine H1 and five subtypes of muscarinic receptors, and has been shown to improve both the positive and negative symptoms of schizophrenia. Olanzapine is extensively metabolised and distributed throughout the body, although the principal metabolites are thought to lack pharmacological activity. No metabolites accumulate in plasma on chronic dosage. Dosage is normally 5-20 mg/d (BNF recommended limit), but some patients are given up to 60 mg/d. Dose-related side effects associated with olanzapine may include somnolence, weight gain, dizziness, peripheral oedema, and postural hypotension.
Olanzapine assay can be useful to (i) assess adherence, (ii) assess adequacy of dosage, and (iii) investigate suspected acute poisoning. A steady-state reference range of 20 – 40 µg/L has been suggested (12h post-dose sample).
Sample Requirements
4 mL of ETDA whole blood is preferred. Serum or plasma can be used if required, but please avoid gel-separator tubes.
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
Please use the form below, COMPLETE ALL FIELDS, and send as a hard copy with the sample.
PDF Request Form
Download Olanzapine Request Form
Turnaround Time
Results are available within 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
Simon Handley
T 020 3299 5883
F 020 3299 5888
References
RJ Flanagan. TDM of antipsychotics. CPD Bull Clin Biochem (2006); 7: 3-18.
