Oxcarbazepine Metab (Trileptal)

Test Code
OXC( 36637)

Quest Code

CPT Codes


Preferred Specimen
1 mL serum collected in a red-top tube (no gel)

Minimum Volume
0.25 mL

Other Acceptable Specimens
Plasma collected in an EDTA (lavender-top) tube

Transport Temperature
Refrigerated (cold packs)

Specimen Stability
Room temperature: 72 hours
Refrigerated: 14 days
Frozen: 60 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Serum separator tubes (SST®)

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

Setup Schedule
Set up: Mon-Sat; Report available: 1-3 days

Reference Range
10-Hydroxycarbazepine 8.0-35.0 mcg/mL

Clinical Significance
Oxcarbazepine (trileptal) is an anti-convulsant used for treating generalized tonic-clonic and partial seizures. It can be administered alone or as an adjunct to other anti-convulsants. Clinically significant effects of oxcarbazepine are observed when plasma levels of its active metabolite, 10-OH-carbazepine, are between 15 and 35 ug/mL. Toxic symptoms may occur when plasma levels exceed 35 ug/mL. The therapeutic monitoring of oxcarbazepine and its active metabolite are important for achieving proper serum/plasma concentration to inhibit epileptic seizures and avoid adverse effects. The precise mechanism of the action by which oxcarbazepine and its active metabolite exert their antiseizure effect is unknown. However, in vitro electro-physiological studies indicate that they produce blockade of voltage-sensitive sodium channels, resulting in the stabilization of hyperexcited neural membranes, inhibition of repetitive neuronal firing, and diminution of propagation of synaptic impulses. These are important in prevention of seizure spread in the brain. In addition, the increased potassium conduction and calcium channel activities may contribute to the antiseizure treatment effects. After oral administration, oxcarbazepine is readily absorbed in the body, followed by rapid and almost complete metabolization to 10-OH-carbazepine, active metabolite. The half-life of oxcarbazepine is only 1 to 2.5 hours, while that of 10-OH-carbazepine is 11 to 15 hours. The protein binding of oxcarbazepine is about 67%, whereas that of the metabolite is about 38%. The clearance of oxcarbazepine and its active metabolite from the body is mainly through ketone reduction and O-site conjugation with glucuronic acid rather than oxidative processes via cytochrome P450 system. More than 95% of the treatment dosage is excreted by the kidneys. Fecal excretion only accounts for less than 4%.

Performing Laboratory
Quest Diagnostics Nichols Institute
27027 Tourney Road
Valencia, CA 91355-5386

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.