[Concentration of phenobarbital in biological fluids during the treatment of epilepsy patients].

Using gas liquid chromatography, the authors studied phenobarbital levels in the blood and cerebrospinal fluid of 41 epileptic patients following the administration of this anticonvulsant alone. The data obtained showed variations in the concentration of blood phenobarbital at various time intervals after the intake of the drug and a certain correlation between its level and the therapeutic effect. The ratio of phenobarbital level in the cerebrospinal fluid to that in the blood indicates that phenobarbital penetrates the blood-brain barrier. Fluctuations in the blood phenobarbital content from one administration to another is important for selecting its optimal dosage and the interval between intakes.