Ordering Recommendation

Use to optimize drug therapy and monitor patient adherence.


Quantitative High Performance Liquid Chromatography-Tandem Mass Spectrometry


Mon, Wed, Sat


1-5 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Plain Red, Lavender (K2 or K3EDTA) or Pink (K2EDTA).

Specimen Preparation

Separate from cells ASAP or within two hours of collection. Transfer 2 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.3 mL)

Storage/Transport Temperature

Refrigerated. Also acceptable: Room temperature or frozen.

Unacceptable Conditions

Gel separator tubes. Hemolyzed specimens.


Ambient: 3 days; Refrigerated: 2 weeks; Frozen: 2 months (Avoid repeated freeze thaw cycles)

Reference Interval

Test Number
Reference Interval
  Clobazam 30-300 ng/mL
  N-Desmethylclobazam 300-3000 ng/mL

Interpretive Data

Clobazam is a benzodiazepine drug indicated for adjunctive treatment for seizures associated with Lennox-Gastaut syndrome in patients 2 years and older.  The therapeutic range is based on serum, pre-dose (trough) draw collection at steady-state concentration. The pharmacokinetics of clobazam are influenced by drug-drug interactions and by poor CYP2C19 metabolism. Adverse effects may include constipation, somnolence, sedation, and skin rash. The concomitant use of clobazam with other central nervous system (CNS) depressants may increase the risk of somnolence and sedation.

Interpretive Data
Clobazam Toxic: Greater than 500 ng/mL
N-Desmethylclobazam Toxic: Greater than 5000 ng/mL

Compliance Category

Laboratory Developed Test (LDT)


Hotline History


CPT Codes

80339 (Alt code: G0480)


Component Test Code* Component Chart Name LOINC
3002509 Clobazam 3487-6
3002510 N-Desmethylclobazam 35107-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • Onfi
  • Sympazan
Clobazam and Metabolite, Quantitative, Serum or Plasma