Felbamate, Serum or Plasma

CPT: 80167
8016780167
8016780167
Updated on 12/4/2022
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Synonyms

  • Felbatol®

Expected Turnaround Time

2 days

2 - 4 days

2 days days


Related Documents


Specimen Requirements


Specimen

Serum or plasma


Volume

2 mL


Minimum Volume

0.5 mL


Container

Red-top (no additive) tube or green-top (heparin) tube; gel-barrier tubes not recommended

Red-top tube, lavender-top (EDTA) tube, or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.

Red-top (no additive) tube or green-top (heparin) tube; gel-barrier tubes not recommended


Collection

Transfer separated serum or plasma to a plastic transport tube. Trough levels are most reproducible.

Transfer separated serum or plasma to a plastic transport tube.

Transfer separated serum or plasma to a plastic transport tube. Trough levels are most reproducible.


Storage Instructions

Submission/transport (<3 days): Room temperature. For storage beyond three days, specimen should be refrigerated or frozen.

Room temperature

Submission/transport (<3 days): Room temperature. For storage beyond three days, specimen should be refrigerated or frozen.


Test Details


Use

Therapeutic drug management

Evaluate toxicity; monitor therapeutic levels

Therapeutic drug management


Limitations

In-house validated method

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

In-house validated method


Methodology

Liquid chromatography/tandem mass spectrometry (LC/MS-MS)


Reference Interval

40–100 µg/mL; stated range of 40–100 µg/mL is the observed range of concentrations in patients successfully treated with felbamate without apparent ill effect. The therapeutic range is not established.

Therapeutic: 25−104 μg/mL; steady-state trough levels are dose proportional in adults. Multiple daily doses of 1200, 2400, and 3600 mg/day gave trough levels of 25−35, 47−63, and 62−104 μg/mL, respectively. Steady-state peak concentrations are dose proportional in children ages 4 to 12 years over a range of 15, 30, 45 mg/kg/day. The dose proportional peak concentrations were reported as 17, 32, and 49 μg/mL, respectively at two to six hours postdose. Co-administration of carbamazepine, phenytoin, phenobarbital, or primidone can cause a decrease in felbamate plasma concentrations; conversely, valproic acid can increase concentrations.1 In children, a similar effect was found with carbamazepine and phenytoin decreasing levels and an opposite effect with valproic acid.2

40–100 µg/mL; stated range of 40–100 µg/mL is the observed range of concentrations in patients successfully treated with felbamate without apparent ill effect. The therapeutic range is not established.


LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
716530 Felbamate (Felbatol(R)), Serum 6899-9 716531 Felbamate, Serum ug/mL 6899-9

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