General information:
Substance group: Tricyclic antidepressant ATC: N06AA12
Trade names: Doxepin*®, Aponal®, Doxepia®, Mareen®
available dosages: film tablets 5 / 10 / 25 / 50 / 100 mg, solution for taking 10 mg/mL,
Solution of injection 12.5 mg/mL
Reference ranges:
Doxepin: 30 – 100 µg/L
Doxepin + Nordoxepin: 50 – 150 µg/L
Toxic plasma mirrors: Doxepin: 500 – 1000 µg/L
Doxepin + nordoxepin: 300 µg/L
Pharmacokinetics:
T1⁄2 : 11 h (i.v.); 8,2 – 24.5 h (oral) (metabolite: 33.2 – 80.7 h)
Tmax: 2 – 4 h (metabolite: 2 – 10 h)
Bioavailability: 27%
Protein binding: 80%
Clearance: 15.5 mL/min (metabolite: 64 mL/min)
Excretion: Urine: predominantly
Metabolism: hepatic
Distribution volume: 22 L/kg KG
Time to steady state: 2 weeks
Sampling:
Material: Serum (Monovette brown) Minimum volume for analysis: 500µl
Recommendation: trough level (directly before the next intake)
Requirement (internal): … 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 release: on the same working day, via LIMS
DrugBank: https://go.drugbank.com/drugs/DB01142