Sir.—We read with interest the study by Yazdani et al1 on the increased theophylline requirements for the control of apnea in premature infants who are also receiving phenobarbital for seizure control. Unfortunately, their retrospective study did not include infants' serum theophylline levels before and after institution of phenobarbital therapy.
Patient Report.—Starting on the second day of life, we administered aminophylline for the treatment of apnea to a 640-g (birth weight) infant who was of 24 weeks' gestation. Minimal ventilatory support was subsequently necessary. A therapeutic serum theophylline level of 9.4 mg/L (52 μmol/L) was achieved with a 5.5-mg/kg loading dose of aminophylline (theophylline ethylene diamine), followed by a maintenance dosage of 2.0 mg/kg/24 h, administered intravenously. On the fourth day of life, phenobarbital sodium, in a loading dose of 20 mg/kg, was administered intravenously following seizure activity. Cranial ultrasonography disclosed a grade 2 intracranial hemorrhage. The seizures