Phenobarbital, plasma or serum

Lab area

Clinical Biochemistry - TDM & Toxicology

Method and equipment

Equipment : Roche Cobas Pro c503

Method : The assay is based on the kinetic interaction of microparticles in a solution (KIMS). Phenobarbital antibody is covalently coupled to microparticles and
the drug derivative is linked to a macromolecule. The kinetic interaction of microparticles in solutions is induced by binding of drug-conjugate to the antibody on the microparticles and is inhibited by the presence of phenobarbital in the sample. A competitive reaction takes place between the drug conjugate and phenobarbital in the serum sample for binding to the phenobarbital antibody on the microparticles. The resulting kinetic interaction of microparticles is indirectly proportional to the amount of drug present in the sample.

Expected turn-around time

STAT/ Urgent / Routine: 2 hours

Specimen type

Serum, Plasma Lithium Heparin

Specimen requirements

150 uL

Storage and transportation

4°C (transport with a cool pack if possible)

Shipping information

The Hospital for Sick Children

Rapid Response Laboratory

555 University Avenue, Room 3642

Toronto, ON

Canada

M5G 1X8

Phone: 416-813-7200

Toll Free: 1-855-381-3212

Hours: 7 days/week, 24 hours/day

Requisition

Phenobarbital, plasma or serum - requisition

Background and clinical significance

Phenobarbital is the most effective barbiturate in long-term treatment of seizure disorders. Strong correlation has been observed between serum levels and both therapeutic and toxic effects. Phenobarbital is excreted, partly metabolized and partly unchanged, very slowly through the urine. Both metabolism and clearance are highly variable among individuals; therefore, close monitoring of serum levels is essential for every patient undergoing phenobarbital therapy. Clinical observations indicate that toxicity of phenobarbital is increased in patients with renal disease. Phenobarbital toxicity primarily affects the central nervous system. Some patients on long term therapy may develop macrocytosis, megaloblastic anemia and osteomalacia.

Disease condition

Anticonvulsant