Phenobarbitone should be given for about 2 – 3 weeks to allow for serum levels to stabilise before checking therapeutic concentrations.

Monitoring of therapeutic levels of phenobarbitone should be assessed at 8 – 12 hours post treatment. Peak levels occur about 5 hours post treatment.

Therapeutic levels for phenobarbitone are 15 – 40 μg/mL

SERUM GEL TUBES MUST NOT BE USED FOR PHENOBARBITONE ANALYSIS