Optimize drug therapy and monitor patient adherence.
Within 24 hours
Allow specimen to clot completely at room temperature. Ensure complete clot formation has taken place prior to centrifugation. Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to an ARUP Standard Transport Tube. (Min: 0.5 mL)
Separator tubes or potassium oxalate/sodium fluoride tubes. EDTA plasma.
After separation from cells: Ambient: 24 hours; Refrigerated: 7 days; Frozen: 1 month
Therapeutic range: 4.0-12.0 µg/mL
Toxic: greater than 15.0 µg/mL
The therapeutic range is based on serum pre-dose (trough) draw at steady-state concentration. Carbamazepine is also subject to drug-drug interactions due to displacement of protein binding and extensive metabolism. Cross-reactivity with metabolites may account for differences in carbamazepine among analytical methods.
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 prior to treatment is recommended for patients at risk for 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 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 who are at increased risk for developing carbamazepine-induced adverse events due to rare genotypes other than HLA-B*15:02 variant allele.
|Component Test Code*||Component Chart Name||LOINC|
- Tegretol, total serum concentration
- Total Carbamazepine