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Zonisamide Level

Zonegran

Test Codes

Antrim #19574, EPIC: LAB5433, SOFT: ZONIS

Department

Toxicology

Specimen Collection Criteria

Collect: One plain Red-top tube. (Minimum Whole Blood: 2.0 mL)

Do not use Serum Separator Tubes.
Time of Collection: Trough, just prior to the next dose.
Record the exact time of specimen collection on the tube or in the computer system.

Physician Office/Draw Specimen Preparation

Let specimens clot 30-60 minutes. Refrigerate (2-8°C or 36-46°F) the collection tube within two hours of collection. (Minimum: 2.0 mL blood)

Preparation for Courier Transport

Transport: Collection tube, refrigerated (2-8°C or 36-46°F). (Minimum: 2.0 mL blood)

Rejection Criteria

• Serum Separator (SST) tubes.
• Severely lipemic or hemolyzed specimens. 

In-Lab Processing

Let specimens clot 30-60 minutes. Centrifuge specimen to separate serum from cells. Deliver an aliquot of serum or the collection tube immediately to the appropriate testing station.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Specimen Storage in Department Prior to Disposal:

Frozen (-20°C/-4°F or below): 2 months

Laboratory

Royal Oak Toxicology Laboratory

Performed

Monday, Wednesday, Friday.
Results available the same day as testing performed (1-3 days).

Reference Range

Therapeutic Range: 10-40 mcg/mL.
Critical Value: 80 mcg/mL.

Test Methodology

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

This test was developed and its performance characteristics determined by Beaumont Health. It has not been cleared or approved by the FDA. The Laboratory is regulated under CLIA as qualified to perform high-complexity testing. This test is used for clinical purposes and should not be regarded as investigational or for research.

Interpretation

Zonisamide is distributed extensively to red blood cells. Hemolysis will falsely elevate serum measurements. Zonisamide has an extended elimination half-life (2-3 days) and time to steady-state may be two weeks. Zonisamide is eliminated by renal and metabolic means. A decline in renal function will increase Zonisamide steady-state concentrations. Concurrent drugs that induce hepatic metabolism (Phenytoin, Phenobarbital, Carbamazepine) will typically decrease steady-state Zonisamide concentrations.

Clinical Utility

Zonisamide is approved as adjunct therapy in the treatment of partial seizures in adults with epilepsy.

CPT Codes

80203
LOINC:  29620-2

Contacts

Last Updated

1/17/2023