Pathology Handbook

Quetiapine

Synonyms

Seroquel, Seroquel XL

Clinical Indications

Quetiapine is a dibenzothiazepine derivative used as an antipsychotic drug in schizophrenia and bipolar disorder. It acts on the chemical neurotransmitters in the brain. The assay can be useful in:

1) Assesing compliance

2) Dose adjustments

3) Investigation of suspected acute poisoning

Drug Kinetics

It is given in incremental doses to target dose of 300-400mg per day by day 4. The effective therapeutic dosage is 200-750 mg/day. It is usually taken three times a day. The half life is 6 hours. Steady state is achieved 3 days after a change of dose. Elimination is by hepatic metabolism and biliary excretion.

Request Form 

ICE request

Availability

Monday to Friday, routine hours in referral laboratory.

Specific Criteria

Samples should be collected pre-dose.

Patient Preparation

Samples should be collected pre-dose.

Turnaround Time

5 working days from reciept of the sample.

Volume

4ml. Minimum, 2ml.

Container

Plastic EDTA Vacutainer (lemon top)

Vacutainer lemon top

Lab Handling

DO NOT SEPARATE. Store whole blood at 4°C. Sample is sent to Llandough Hospital Toxicology Laboratory analysis. 

Causes for Rejection

Unlabelled or incorrectly labelled sample.

Taken at inappropriate time.

Request not justified.

Reference Range

200-600 µg/L