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Test Code
This test is a lab developed test. For further information, see the Compliance Remarks section below.
SynonymsAdapin; Nordoxepin; Prudoxin; Sinequan; Zonalon
Container TypeRed top tube (plain)
Supply Item Number1372
Specimen TypeSerum
Preferred Volume0.5 mL
Emergency Minimum Volume0.2 mL
Patient PrepTiming of specimen collection: Pre-dose (trough) draw - At steady state concentration.
Collection ProcedureOptimal time to collect sample: Draw 10-14 hours post-dose. If a divided dose is given, draw before morning dose.
Specimen ProcessingBlood samples should be collected by venipuncture in a plain red top and serum samples must be allowed to clot naturally at room temperature. Separate serum from cells within 4 hours and place in separate polypropylene (not polystyrene) tube.
Store and TransportRefrigerated
Required Patient InfoDate and time of dose and draw
StabilityRoom Temp 5 days  Refrigerated 1 week  Frozen (-20 °C) 1 month  Frozen (-70 °C) 1 year  
Unacceptable ConditionDO NOT use gel separator tubes (Corvac®, SST or equivalent) for the collection of blood samples for this test.
Reference LaboratoryPAML
Reference Lab Test CodeLCA code 911179
CPT Codes80335, (HCPCS G0480)
Interface Order Code80166.Z3
Billing CodeDOXMP
Test ScheduleMon, Wed, Fri
Turnaround Time1-3 days
MethodTandem Mass Spectrometry
Reference Ranges
DoxepinNot establishedng/mL
NordoxepinNot establishedng/mL
Total (Doxepin + Nordoxepin)Therapeutic50-150ng/mL
Toxic> 150ng/mL
Compliance RemarksThis test was developed and its performance characteristics determined by PAML. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test. However, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. PAML is authorized under Clinical Laboratory Improvement Amendments (CLIA) to perform high-complexity testing.
NotesPlasma concentrations vary widely among patients. The therapeutic range listed relates to the antidepressant characteristics of the drug. A therapeutic range for treating obsessive compulsive disorder is not well defined.

Interface Codes
typeorder codetest descriptionresult coderesult descriptionunitsdecimal placesloinc code
o80166.Z3Doxepin and Metabolite
r80166.Z3Doxepin and Metabolite80166.Z1Doxepinng/mL 3579-0
r80166.Z3Doxepin and Metabolite80166.Z2Doxepine/Nordoxepine Totalng/mL 3582-4
r80166.Z3Doxepin and Metabolite80299.Z71Nordoxepinng/mL 3862-0