Topiramate, Serum or Plasma
Also known as: Topamax®
Use
Topiramate is an anticonvulsant drug used in adjunctive therapy for treating partial and secondary generalized epilepsy. It primarily acts by blocking the spread of seizures rather than raising the seizure threshold. Despite inducing agents like carbamazepine and phenytoin affecting its metabolism, topiramate considerably influences its therapeutic plasma levels. It is important to monitor interpatient variability in clinical response to topiramate at similar plasma concentrations, as such variations can be significant.
Special Instructions
Separate serum from cells within 45 minutes of collection for serum samples. For plasma samples, separate immediately and transfer to a plastic transport tube. Samples should be collected immediately prior to the next dose of the drug.
Limitations
Topiramate concentrations can be influenced by co-medications like carbamazepine or phenytoin, which induce its metabolism. Valproic acid has a lesser effect. The absorption of topiramate by gel-barrier tubes can lower drug levels significantly, so such tubes should not be used. Hemolyzed, clotted, or gel separator tube samples are prone to rejection.
Methodology
Immunoassay (Homogeneous Enzyme Immunoassay)
Biomarkers
LOINC Codes
- 17713-9
- 17713-9
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
0.5 mL
Minimum Volume
0.3 mL
Container
sodium heparin tube, potassium (EDTA) tube, or lithium (heparin) tube
Collection Instructions
Separate plasma immediately and transfer to a plastic transport tube for shipment.
Patient Preparation
Collect samples immediately prior to next dose.
Storage Instructions
Store at room temperature.
Causes for Rejection
Hemolyzed samples; gel separator tubes; clotted specimen; samples not separated from blood cells
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 7 days |
| Frozen | 4 weeks |