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Test Code PHENB Phenobarbital

Important Note

Sample must be centrifuged and separated within 1 hour of collection.

Additional Codes

Epic: LAB30

Specimen Required

Specimen Type: Serum

Collection Container/Type

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 3.5 mL

Collection Instructions: Centrifuge and separate cells after clot formation and within 1 hour of collection.  

Additional Information: The patient's clinical condition and dosage regiment may influence the sample collection time.

Specimen Minimum Volume

0.5 mL

Specimen Stability

Room temperature: 2 days

Refrigerated: 8 days

Frozen: 6 months

Reference Range

Therapeutic: 15.0 - 40.0 µg/mL

Report Available

Same day

Clinical Significance

Phenobarbital was introduced in 1912 for the treatment of epilepsy, particularly for controlling focal motor or sensory seizures and grand mal seizures. Phenobarbital is bound to both plasma and tissue proteins. Monitoring serum concentrations of Phenobarbital has been shown to improve patient therapy by providing physicians with a tool for adjusting dosage. In addition, because of the narrow therapeutic index and wide inter-individual variability in the rate of phenobarbital metabolism and clearance, the determination of blood levels of phenobarbital for patients receiving therapy is essential.

Method Name

Chemiluminescent Microparticle Immunoassay (CMIA)


Barbita (Phenobarbital)
Solfoton (Phenobarbital)

Day(s) Performed