Phenobarbital, Serum or Plasma

Also known as: Luminal®, Phenobarbital Level, Blood

Clinical Use

Use

Phenobarbital, a long-acting barbiturate, is effective in generalized tonic-clonic and simple partial seizures. Higher plasma concentrations may be required to control the latter. Complex partial seizures do not respond as well, and absence seizures are not relieved and may be exacerbated. Phenobarbital frequently is used in the treatment of neonatal seizures and may be the initial drug employed in young children; however, because of increasing concern about adverse neuropsychological reactions to sedative/hypnotic antiepileptic drugs, many neurologists prefer less sedating drugs, such as carbamazepine, phenytoin, or valproate. The prophylactic use of phenobarbital in infants with febrile seizures has been challenged. Phenobarbital also is useful in seizures caused by barbiturate withdrawal in dependent individuals. The sodium salt is administered parenterally as part of the treatment regimen for status epilepticus.

Special Instructions

Not provided.

Limitations

The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel, potentially affecting drug level measurement. Depending on volume and storage conditions, drug absorption into the gel can be clinically significant. Patients on phenobarbital should be monitored due to its interaction with various drugs that can affect clearance and elimination. Furthermore, its effectiveness can vary among different seizure types.

Test Details