Abstract
The pharmacokinetics and the pulmonary function were studied in asthmatic children aged 7 to 14 years, treated in once-a-day administration with sustained-release theophylline formulation (Theodur®), and compared with twice daily administration. The mean time to reach maximum concentration (Tmax) in serum, in once-a-day administration (taken ao 9:00AM) was 8.6 hours, where the maximum concentration (Cmax) was 18.3μg/ml and the minimum concentration (Cmin) being 3.4μg/ml. In comparison with twice daily administration (taken at 9:00AM and 900PM), the serum theophylline concentration at 5:00AM, 7:00AM and 9:00AM were significantly higher (P<0.01). There was a significant correlation between Cmax in once-a-day and twice daily (r=0.660 P<0.05). The pulmonary function showed a significant improvement at 5:00AM in once-a day.
From these results, we assert that once-a-day administration of sustained-release theophylline formulation (Theodyr®), is useful to inhibit the morning dip in asthmatic children. However, drug monitoring in required to prevent unexpected overdoses, and twice daily administration should be choiced for the treatment of sever asthmatic children to maintain serum concentration wihtin the effective range during day time.
