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Preferred Sample Type


Suitable Specimen Types

  • Serum
  • EDTA Plasma
  • Li Hep Plasma
A minimum of 50 µl of plasma/serum is required.

Sample Processing in Laboratory

Place sample in toxicology rack.

Sample Preparation

None required

Turnaround Time

3 days.

Sample Stability

Keep refrigerated. 4 degrees.


General Information

Quetiapine is a dibenzothiazepine derivative, structurally related to cloazapine which has been used clinically since 1997 as a neuroleptic agent in the treatment of psychosis. Daily doses may range from 150 - 800 mg and are usually administered in 2 - 3 portions. 

Adverse reactions to quetiapine therapy include somnolence, hypertension, dizziness, dry mouth and dyspepsia. Neuroleptic malignant syndrome has also been reported.

Patient Preparation

For TDM, sample should be taken prior to dose. If toxicity is suspected, take sample at earliest opportunity


Quetiapine measured by LC-MS/MS.


Reference Range

Therapeutic range: 100 - 500 μg/L. Toxicity associated with concentrations >1000 μg/L. (Schulz et al. Critical Care 2012, 16:R136).


  • EQA Scheme?: Yes
  • EQA Status: LGC TDM