Serum theophylline levels in asthmatic children after oral administration of a slow-release aminophylline preparation (Phyllocontin Continus tablets).

Twenty-seven asthmatic children aged 3--14 years who were considered to need continuous treatment were studied. Fifteen received a low dose of slow-release aminophylline and fifteen a high dose. There was a wide range of serum theophylline levels between individuals for similar doses. Fourteen of twenty children who had five or more levels measured throughout the day had differences between maximum and minimum levels of greater than 4 microgram/ml. The peak levels occurred between 2 and 6 hours after the dose. Only four children had levels exceeding 20 microgram/ml and none was symptomatic. We suggest a dose of 14 mg/kg/dose twice daily which should be reviewed after peak serum theophylline levels are measured.