256 THEOPHYLLINE HALF-LIFE IN INFANTS AND YOUNG CHILDREN

Theophylline half-life determination kinetics were performed in 54 young children. Our patients ranged in age from three months to six years, with a mean age of 2.2 years. Mean half-life determined was 4.92 hours with a standard deviation of 1.88 hours, which is at considerable variance with previously quoted half-lives for young children. Computerized multiple regression analyses with doses of 3, 4, 5 mg/kg of theophylline every six hours were performed, and maximum, minimum, and mean steady state serum levels were developed. Five mg/kg theophylline appeared to be a safe dosage in the majority of children. Two of our subjects developed peak levels greater than 25 mcg/ml, and no toxicity was noted. Age and half-lives were compared, and there was found to be no correlation in this young age group. Theophylline half-life in young children was found to be considerably longer than previously recorded. The published values of theophylline safety range levels, e.g., less than 20 mcg/ml, need to be reconsidered.