Accuracy of five methods for predicting phenobarbital concentrations in pediatric patients.
Four published methods of predicting steady-state phenobarbital concentrations were evaluated and compared with a new method. In phase 1, steady-state serum phenobarbital concentrations were obtained from 36 complaint patients who were 6 months to 15 years old. Patients were stratified into five groups according to weight. Each patient's steady-state serum phenobarbital concentration was then predicted using clearance (CL) values from four published methods (methods 1-4), and these serum-concentration values were compared with actual steady-state concentrations. In phase 2, 17 new patients were selected. The mean CL values determined for each weight group of phase 1 patients were incorporated into another method (method 5) and used to calculate steady-state phenobarbital concentrations for phase 2 patients. In both study phases, predicted concentrations were compared with both the actual concentration in each patient and a naive predictor. In phase 1, method 1 was the least biased; methods 2-4 were significantly biased and were not significantly better than the naive predictor. In phase 2, methods 1-4 were more biased and less precise than method 5. In both study phases, methods 2-4 consistently under-predicted phenobarbital concentrations. The prediction method based on clearance data obtained in a group of pediatric patients at our institution (method 5) appears to be more useful for predicting serum phenobarbital concentrations than four other prediction methods based on published clearance values.
D000293:Adolescent; D001682:Biological Availability; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D007700:Kinetics; D008657:Metabolic Clearance Rate; D010634:Phenobarbital / Q000378:metabolism*; D011336:Probability
D010634:Phenobarbital