The effect of phenobarbital on theophylline disposition in children with asthma.
The disposition of theophylline was examined in seven children with asthma on two occasions before and on one occasion after chronic phenobarbital dosing (2 mg/kg/day). There was little intrapatient variability in apparent theophylline clearance between the two baseline assessments (0.081 versus 0.073 L/hr/kg). After 19 days of phenobarbital therapy, there was a significant increase in apparent theophylline clearance (0.104 versus 0.077 L/hr/kg), accompanied by a 30% decrease in the mean steady-state serum theophylline concentration (12.0 versus 8.4 micrograms/ml). The inducing effect of phenobarbital on theophylline metabolism may require theophylline dosage adjustment in patients with asthma who receive both drugs concurrently to maintain a given average steady-state theophylline concentration.
D001249:Asthma / Q000188:drug therapy*; D002648:Child; D004334:Drug Administration Schedule; D004347:Drug Interactions; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D010634:Phenobarbital / Q000008:administration & dosage* / Q000627:therapeutic use; D013806:Theophylline / Q000097:blood* / Q000627:therapeutic use
D013806:Theophylline; D010634:Phenobarbital