General information:
Substance group: Antipsychotic ATC: N05AH04
Trade names: Quentiax®, Quetiapine*®, Seroquel®
available dosages: film tablets 25 / 50 / 100 / 150 / 200 / 300 / 400 mg,
Retard tablets 50 / 150 / 200 / 300 / 400 mg
Reference ranges:
100 – 500 µg/L
Toxic plasma concentrations: >1000 µg/L
Sampling:
Material: Serum (Monovette brown) Minimum volume for analysis: 50µL
Recommendation: trough level (directly before the next intake)
Requirement (internal): about …. Requirement (external):
Analytics:
Test principle: liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS)
Protein precipitation with acetonitrile, chromatographic separation, mass spectrometry
Analysis according to mass charge ratio
Analysis system: triple stage Quadrupol mass spectrometer (LC-MS/MS)
Findings communication: on the day of submission, via LIMS
T1/2 : 3 – 7 h (metabolite: 12h)
Tmax : 1,5 h
Time to steady state: 2-3 days
Bioavailability: 9%
Protein binding: 83%
Distribution volume: 10 l/kg
Clearance: 55-105 l/h
Excretion: 73% renal (5% unchanged), 21% faeces
Metabolism: metabolism mainly via CYP3A4,
Active metabolite: N-desalkylquetiapine/Norquetiapine (35%)
Drug interactions: CYP3A4 inhibitors (HIV protease inhibitors, Azol antifungal, erythromycin, clarithromycin, nefazodone), caution with concomitant use of anticholinergic agents and drugs which might cause QT interval prolongation
Indication:
Level 2: TDM recommended
TDM at least every 3-6 months or more frequently in case of dose titration, suspected non-adherence, dosage alterations, changes in comedication, adverse drug effects, insufficient clinical improvement.
DrugBank: https://go.drugbank.com/drugs/DB01224