Monitoring serum concentration during therapy
Evaluating potential toxicity
Evaluating patient compliance
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Effexor (Venlafaxine)
Effexor XR
Venlafaxine (Effexor)
VENLA
Serum Red
Collection Container/Tube: Red top (serum gel/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Draw blood immediately before next scheduled dose.
2. Blood drawn from patients 12 hours after an oral dose is also appropriate. It is customary to treat the patient at bedtime with a dose, and then collect specimen the following morning prior to next dose.
3. Centrifuge and aliquot serum into a plastic vial within 2 hours of collection.
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.
0.4 mL
Gross hemolysis | OK |
Gross lipemia | OK |
Gross icterus | OK |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum Red | Refrigerated (preferred) | 28 days | |
Ambient | 28 days | ||
Frozen | 28 days |
Monitoring serum concentration during therapy
Evaluating potential toxicity
Evaluating patient compliance
Venlafaxine is a serotonin and norepinephrine reuptake inhibitor approved for treatment of major depression, anxiety and panic disorders, and social phobias. It is also used for bipolar disorder, bulimia, post-traumatic stress, obsessive behavior, and attention-deficit disorder. Venlafaxine is converted by cytochrome P450 (CYP) 2D6 to the active metabolite, O-desmethylvenlafaxine. The therapeutic range for venlafaxine includes measurement of O-desmethylvenlafaxine; optimal response is seen when combined concentrations of parent and metabolite are between 100 and 400 ng/mL. Venlafaxine is significantly affected by reduced hepatic function but only slightly by reduced kidney function.
Average elimination half-lives are 5 hours for venlafaxine and 10 hours for O-desmethylvenlafaxine, which are much shorter than many other antidepressants. For this reason, extended-release formulations are available. Time to peak serum concentration is 2 hours for the regular product and 8 hours for the extended-release product. Common toxicities are mild, including drowsiness, dizziness, nausea, and headache.
Venlafaxine + O-desmethylvenlafaxine: 100-400 ng/mL
Most individuals display optimal response to venlafaxine when combined serum levels of venlafaxine and O-desmethylvenlafaxine are between 100 and 400 ng/mL. Some individuals may respond well outside of this range or may display toxicity within the therapeutic range; thus, interpretation should include clinical evaluation. Risk of toxicity is increased with combined levels greater than 800 ng/mL. Therapeutic ranges are based on specimens collected at trough (ie, immediately before the next dose).
Specimens that are obtained from gel tubes are not acceptable as the drug can absorb on the gel and lead to falsely decreased concentrations.
1. Wille SMR, Cooreman SG, Neels HM, Lambert WEE: Relevant issues in the monitoring and toxicology of antidepressants. Crit Rev Clin Lab Sci. 2008;45(1):25-89
2. Baumann P, Hiemke C, Ulrich S, et al: The AGNP-TDM expert group consensus guidelines: therapeutic drug monitoring in psychiatry. Pharmacopsychiatry. 2004 Nov;37(6):243-265
3. Rifai N, Horvath AR, Wittwer CT, eds: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018
4. 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
Venlafaxine and its metabolite are measured using acetonitrile precipitation and analysis by high-performance liquid chromatography-tandem mass spectrometry.(Unpublished Mayo method)
Thursday
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.
80299
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
VENLA | Venlafaxine, S | 62849-5 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
83732 | Venlafaxine | 9630-5 |
30195 | O-desmethyl Venlafaxine | 9630-5 |
32182 | Venlafaxine+O-Desmethylvenlafaxine | 62849-5 |