Sign in →

Epic Test Code LAB686 Felbamate (Felbatol), Serum

Additional Codes

MML Code: FELBA

LIS Code: FELB

NY State Approved

Yes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

Felbamate (Felbatol), S

Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days


Specimen Required


Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. Draw blood immediately before next scheduled dose.

2. Centrifuge and separate serum from cells or gel within 2 hours of draw.


Specimen Type

Serum

Specimen Minimum Volume

0.5 mL

Reference Values

30.0-60.0 mcg/mL

Analytic Time

Same day/1 day

Day(s) and Time(s) Performed

Monday, Wednesday, Friday; 3 p.m.

CPT Code Information

80299

Reject Due To

Hemolysis

Mild OK; Gross OK

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

NA

Clinical Information

Felbamate is an anticonvulsant drug approved for treatment of partial seizures with or without secondary generalization in persons 14 years of age and older. It is also approved for Lennox-Gastout syndrome in children 2 years of age and older. Felbamate is well absorbed (>90%) and is metabolized by the hepatic cytochrome P450 system. Metabolites lack anticonvulsant activity. The elimination half-life of felbamate ranges from 13 to 23 hours.

 

Optimal response to felbamate is seen with serum concentrations between 30 mcg/mL to 60 mcg/mL. Patients who are elderly or have renal dysfunction may require reduced dosing; felbamate should not be given to individuals with hepatic disease. Toxicity can be severe, including life-threatening aplastic anemia or liver failure, but no defined toxic concentration has been established.

 

Coadministration of felbamate increases the concentration of phenytoin and valproic acid, decreases carbamazepine concentration, and increases carbamazepine-10,11-epoxide (its active metabolite). Conversely, coadministration of phenytoin or carbamazepine causes a decrease in felbamate concentration.

Cautions

No significant cautionary statements

Interpretation

Optimal response to felbamate is associated with serum concentrations of 30 mcg/mL to 60 mcg/mL.

                          

Toxic serum concentrations for felbamate have not been established.

Specimen Retention Time

14 days

Useful For

Determining whether a poor therapeutic response is attributable to noncompliance or lack of drug effectiveness

 

Monitoring changes in serum concentrations resulting from interactions with coadministered drugs such as barbiturates and phenytoin

Forms

If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.