Carbamazepine-10,11-Epoxide, Serum
Use
This test is useful for monitoring patients who exhibit symptoms of carbamazepine toxicity despite their total serum carbamazepine concentration being within the therapeutic range. It helps detect significant levels of the active metabolite carbamazepine-10,11-epoxide, which can accumulate to concentrations equivalent to carbamazepine, potentially leading to toxicity. The test aids in assessing drug interactions and optimal dosing regimens, especially when patients are on other medications that may induce or inhibit liver enzymes affecting carbamazepine metabolism.
Special Instructions
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen. Drawing blood 12 hours post last dose is recommended to ensure trough level measurement for more accurate monitoring.
Limitations
Carbamazepine-10,11-epoxide levels should be interpreted in the context of total carbamazepine serum concentrations and clinical findings, as the exact clinically acceptable serum concentration of the epoxide is not well established. Potential interactions with other medications can alter carbamazepine metabolism, leading to variations in active metabolite concentrations. Therefore, assessing liver enzyme interactions, other anticonvulsants, and valproic acid is crucial to avoid misinterpretation of results.
New York Approved
Methodology
Immunoassay (Homogeneous Microparticle Agglutination Immunoassay)
Biomarkers
LOINC Codes
- 50337-5
- 9415-1
- 3432-2
Result Turnaround Time
1-7 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2 mL
Minimum Volume
1 mL
Container
Red top; Plastic vial
Collection Instructions
Draw blood 12 hours (trough value) after last dose. Centrifuge and aliquot serum into a plastic vial.
Causes for Rejection
Gross hemolysis, Gross lipemia, Gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |
| Refrigerated | 7 days |
| Frozen | 28 days |