PHENOBARBITAL DOSES NECESSARY TO ACHIEVE THERAPEUTIC CONCENTRATIONS IN CHILDREN

Steady-state plasma phenobarbital (PB) concentrations (n = 671) were m easured in 438 inpatients. There was a significant relationship betwee n age and PB dose ratio (concentration/dose or 1/clearance) for monoth erapy patients; the dose ratio declined in the first year of life, but the dose ratio increased after age 1. The dose ratios were significan tly higher in patients receiving PB in combination with other antiepil eptic drugs. However, neither sex nor formulations used (tablet, elixi r and intravenous) had any influence on the PB dose ratio. The age-dos e-concentration relationships indicate that children, especially those under 11 years of age, may require maintenance PB doses more than 5 m g/kg/day to achieve the commonly recommended 'therapeutic' concentrati on range (10-40 mg/1).