The pharmacokinetics of theophylline in an infant with hepatic failure.

In a 6 1/2-month-old infant with hepatic failure secondary to hereditary tyrosinemia, the theophylline clearance rate of 0.016 liter/kg/h was reduced for age and the serum half-life was prolonged to 18.0 h. Theophylline, 3.4 micrograms/ml, and caffeine, 2.2 micrograms/ml, were identified in a urine sample obtained 48 h after the test dose of theophylline, but no 1-methyluric acid, 1,3-dimethyluric acid or 3-methylxanthine were detected. This is the first infant with liver dysfunction and impaired theophylline disposition to be reported.