Ordering Recommendation

Optimize drug therapy and monitor patient adherence.

Mnemonic
CARB EPOXT
Methodology

Quantitative Liquid Chromatography-Tandem Mass Spectrometry

Performed

Mon

Reported

1-8 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation

Timing of specimen collection: Pre-dose (trough) draw - At steady state concentration.

Collect

Plain red. Also acceptable: Lavender (K2 or K3EDTA) or pink (K2EDTA).

Specimen Preparation

Separate serum or plasma from cells within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.5 mL)

Storage/Transport Temperature

Frozen

Unacceptable Conditions

Whole blood. Gel separator tubes, light blue (citrate), or yellow (SPS or ACD solution).

Remarks
Stability

After separation from cells: Ambient: 48 hours; Refrigerated: 1 week; Frozen: 1 month

Reference Interval

Effective November 13, 2017

Available Separately
Components
Therapeutic Range
No Carbamazepine-10, 11 Epoxide Not well established
Toxic:  Greater than 15.0 µg/mL
No Total Carbamazepine Therapeutic Range: 4.0-12.0 µg/mL
Toxic:  Greater than 15.0 µg/mL

Interpretive Data

The therapeutic range is based on serum pre-dose (trough) draw at steady-state concentration. The carbamazepine metabolite, Carbamazepine-10, 11-Epoxide, has anticonvulsant activity and a proposed therapeutic range of 0.4-4 µL/mL. 

A rare, adverse drug reaction to carbamazepine therapy includes Stevens-Johnson syndrome or toxic epidermal necrolysis. Patients of Asian ancestry with the presence of the HLA-B*15:02 have an increased risk for this carbamazepine-induced, life-threatening reaction. Pharmacogenetic testing for HLA-B*15:02 is recommended prior to treatment for patients at risk of carbamazepine hypersensitivity. This information has been included in the FDA-approved label for carbamazepine (<https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&varApplNo=016608>) and in the guideline from the Clinical Pharmacogenetics Implementation Consortium (https://www.pharmgkb.org/guidelines). (HLA-B*15:02 Genotyping, Carbamazepine Hypersensitivity, ARUP test code 2012049.)

A combination of therapeutic drug monitoring with HLA-B*15:02 pharmacogenetics genotyping may benefit patients at increased risk of developing carbamazepine-induced adverse events due to rare genotypes other than the HLA-B*15:02 variant allele.   

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

80156; 80299

Components
Component Test Code* Component Chart Name LOINC
0090616 Carbamazepine, Total 3432-2
0098427 Carbamazepine 10-11 Epoxide 9415-1
* 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.
Aliases
  • 11 Epoxide
  • Atretol
  • Biston
  • Calepsin
  • Carbamazepine - 10,11 Epoxide, Serum or Plasma
  • Carbamazepine and Epoxide Metabolite
  • Carbamazepine Metabolite
  • Carbamazepine-10
  • Carbatrol
  • Epimaz
  • Epitol
  • Epitrol
  • Epoxide 10, 11
  • Equetro
  • Finlepsin
  • Sirtal
  • Tegretol, Metabolite
  • Telesmin
Carbamazepine Epoxide and Total