The study aimed to find the right dosage of theophylline for Korean infants under one year old with asthma. Researchers studied 111 infants and found a formula to calculate the dosage based on age. They also observed a decrease in theophylline levels over time in some infants. The study showed that Korean infants may need different theophylline dosages compared to foreign infants due to differences in metabolism. It was found that most infants experienced side effects at blood levels of 10-12 μg/ml, with the effective range being 5-10 μg/ml. This suggests the need for a new dosage formula tailored to Korean infants and further research on the effects and metabolism of theophylline in this population.