Metaproterenol sulfate for asthmatic children with therapeutic serum theophylline concentrations

The effects of oral metaproterenol sulfate in asthmatic children maintained chronically on therapeutic doses of theophylline were investigated. Metaproterenol sulfate tablets were compared with placebo in a double-blind, cross-over study with 17 asthmatic children (aged 6-11 years) maintained on a sustained-release preparation of theophylline. Spirometric measurements were made to determine the forced expiratory volume in one second (FEV1), and a forced oscillation technique was used to measure total respiratory conductance (TRC). Differences in the variables from baseline studies following the test drug or placebo were recorded at 0.5, 1, 2, 3, and 4 hours after the test dose. Metaproterenol led to a statistically significant improvement in FEV1 and TRC over placebo with a peak difference at three hours (p less than 0.05). The children with a resting FEV1 below 80% predicted experienced the greatest improvement. No serious side effects from metaproterenol were encountered. The forced oscillation technique provided a reproducible noninvasive means of measuring the bronchodilator response in young children. In the recommended doses, metaproterenol can improve pulmonary function in asthmatic children who have abnormal pulmonary function while being maintained on theophylline.