Epic Code LAB3310 Paroxetine, Serum
Additional Codes
Mayo Code: PARO
Epic Code: LAB 3310
CDM: 3421571
Interface Order Alias: 10557
Cerner: 4039
Performing Laboratory
Mayo Clinic Laboratories in RochesterUseful For
Monitoring paroxetine therapy
Identifying noncompliance, although regular blood level monitoring is not indicated in most patients
Identifying states of altered drug metabolism when used in conjunction with CYP2D6 genotyping
Specimen Type
Serum RedSpecimen Required
Collection Container/Tube: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions:
1. Draw blood before next scheduled dose.
2. Centrifuge and aliquot serum into plastic vial within 2 hours of collection.
COLLECTION NOTE: Volumes listed are in serum or plasma, draw approximately 2 1/2 times the requested volume in whole blood.
Specimen Minimum Volume
0.4 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum Red | Refrigerated (preferred) | 28 days | |
Ambient | 28 days | ||
Frozen | 28 days |
Reject Due To
Gross hemolysis | OK |
Gross lipemia | OK |
Gross icterus | OK |
Day(s) Performed
Thursday
Reference Values
20-65 ng/mL
Clinical Information
Paroxetine (Paxil and Paxil CR) is approved for treatment of depression. Paroxetine is completely absorbed. Metabolites of paroxetine are inactive. Paroxetine metabolism is carried out by cytochrome P450 (CYP) 2D6. Paroxetine can saturate CYP2D6 resulting in a nonlinear relationship between dose and serum concentration. Paroxetine clearance is significantly affected by reduced hepatic function but only slightly by reduced kidney function.
A typical adult paroxetine dose is 20 mg per day. Paroxetine is 100% bioavailable, 95% protein bound, and the apparent volume of distribution is 17 L/kg. Time to peak serum concentration is 5 hours for the regular product and 8 hours for the controlled release product. The elimination half-life is 20 hours. Half-life is prolonged in the elderly and with cirrhosis.
Cautions
Specimens that are obtained from gel tubes are not acceptable as the drug can absorb on the gel and lead to falsely decreased concentrations.
Interpretation
Steady-state serum concentrations associated with optimal response to paroxetine are in the range of 30 to 120 ng/mL and in the narrower range of 20 to 65 ng/mL.
The most common toxicities associated with excessive serum concentration are asthenia, anticholinergic effects, anxiety, blurred vision, and changes in sexual function. The toxic range for paroxetine is greater than 120 ng/mL.
Reporting Name
Paroxetine, SMethod Name
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Method Description
Paroxetine, citalopram, venlafaxine, and venlafaxine metabolite are extracted from serum by precipitation with acetonitrile. Dilute methanolic hydrochloric acid is added to form a salt to protect analytes from volatilization during the evaporation of the acetonitrile. High-performance liquid chromatography with detection by tandem mass spectrometer is used to measure concentration.(Unpublished Mayo method)
CPT Code Information
80299
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
PARO | Paroxetine, S | 9699-0 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
83731 | Paroxetine, S | 9699-0 |
Report Available
1 to 4 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.Clinical Reference
1. Hiemke C, Baumann P, Bergemann N, et al: AGNP consensus guidelines for therapeutic drug monitoring in psychiatry: update 2011. Pharmacopsychiatry. 2011 Sept;44(6):195-235
2. Rifai N, Horvath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018
3. Hiemke C, Bergemann N, Clement HW, et al: Consensus guidelines for therapeutic drug monitoring in neuropsychopharmacology: Update 2017. Pharmacopsychiatry. 2018 Jan;51(1-02):9-62
Forms
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.