Serum

Draw immediately before next scheduled dose. Serum drawn from patients 12 hours after an oral dose is appropriate. It is customary to treat the patient at bedtime with a dose, then draw specimen the following morning prior to next dose.

Preferred Minimum: 1 mL serum Absolute Minimum: 0.4 mL serum

Specimens that are obtained from gel tubes.

3 days upon receipt at reference laboratory

Venlafaxine + O-desmethylvenlafaxine: 195-400 ng/mL

The therapeutic range is based on serum pre-dose (trough) draw at steady-state concentration. Adverse effects to venlafaxine therapy may include nausea, vomiting, dizziness, tremor and blurred vision.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Venlafaxine is a serotonin and norepinephrine reuptake inhibitor (SNRI) 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.

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.

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

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