Pathology Handbook

Phenobarbitone

Synonyms

-

Clinical Indications

Phenobarbitone is a second-line drug for partial or tonic seizures and is also used prophylactically in paediatric febrile convulsions.  Patients develop tolerance to the drug and monitoring is useful in the following situations:

  • to improve compliance
  • confirm toxic levels
  • minimise drug interaction when other drugs, e.g. valproate, are added
  • ensure adequate levels are achieved in prophylaxis for febrile convulsions

Request Form 

Request on ICE

Availability

On request

Patient preparation

Samples should be collected immediately before the next dose of drug is due, i.e. trough levels

Specific Criteria

None

Turnaround Time

Weekly 

Specimen

Serum; Yellow top (SST) tube

Volume

2 mL

Container

Vacutainer gold top

Collection

 -

Causes for Rejection

Unlabelled sample

Therapeutic Range

Mass units: 15 - 39 mg/L

(Molar units: 65 - 170 µmol/L)