Doxepin and Metabolite, Serum or Plasma
Also known as: DOXEPIN
Use
The test is used to optimize dosing and monitor patient adherence for doxepin, a tricyclic antidepressant. Monitoring the levels of doxepin and its primary metabolite, nordoxepin, helps ensure therapeutic efficacy and helps avoid toxic concentrations. Therapeutic drug monitoring is crucial for patient safety and effectiveness of treatment.
Special Instructions
Before sample collection, ensure the patient is at a steady-state concentration. Timing is critical, with collection scheduled for a predose (trough) draw. Utilize plain red, lavender (K2 or K3EDTA), or pink (K2EDTA) tubes for specimen collection.
Limitations
The test does not directly measure the efficacy of treatment, but provides data on drug and metabolite concentration levels. Therapeutic and toxic ranges are provided, but individual responses may vary. Toxic concentrations may cause anticholinergic effects and cardiac abnormalities, but not all side effects or symptoms might correlate with concentration levels measured. Interference from certain medications or improper specimen handling could affect accuracy.
New York Approved
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 3579-0
- 3582-4
- 3862-0
Result Turnaround Time
2-8 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
ARUP standard transport tube
Collection Instructions
Separate serum or plasma from cells within 2 hours of collection.
Patient Preparation
Predose (trough) draw at steady-state concentration.
Storage Instructions
Refrigerated.
Causes for Rejection
Whole blood. Gel separator tubes, light blue (citrate), or yellow (SPS or ACD solution).
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 5 days |
| Refrigerated | 2 weeks |
| Frozen | 6 months |
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