The effect of phenobarbital on theophylline disposition in children with asthma

J Allergy Clin Immunol. 1985 Jun;75(6):716-9. doi: 10.1016/0091-6749(85)90099-5.


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.

MeSH terms

  • Asthma / drug therapy*
  • Child
  • Drug Administration Schedule
  • Drug Interactions
  • Female
  • Humans
  • Kinetics
  • Male
  • Phenobarbital / administration & dosage*
  • Phenobarbital / therapeutic use
  • Theophylline / blood*
  • Theophylline / therapeutic use


  • Theophylline
  • Phenobarbital