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No protection by oral terbutaline against exercise-induced asthma in children: a dose-response study
G Fuglsang1, B Hertz, E B Holm
1Pediatric Dept, Viborg Hospital, Denmark.
Insights
Continuous oral terbutaline sulphate did not protect against exercise-induced asthma in children. High doses increased side effects without providing significant clinical benefits for asthma symptom control.
Area of Science:
- Pediatric Pulmonology
- Clinical Pharmacology
Background:
- Exercise-induced asthma (EIA) is a common condition in children.
- Asthma management often involves bronchodilators, but their efficacy in preventing EIA with continuous oral administration requires further investigation.
Purpose of the Study:
- To evaluate the protective effects of increasing doses of sustained-release terbutaline sulphate against exercise-induced asthma in children.
- To assess the clinical efficacy and safety of this new formulation.
Main Methods:
- A randomized, double-blind, cross-over study involving 17 children (aged 6-12 years) with asthma.
- Participants received placebo, 2 mg, 4 mg, or 6 mg of terbutaline sulphate twice daily for 14 days.
- Exercise tests were conducted, and FEV1 (forced expiratory volume in 1 second) and PEF (peak expiratory flow) were measured.
Main Results:
- Terbutaline sulphate did not significantly improve asthma symptoms or protect against exercise-induced asthma compared to placebo.
- A small, dose-related increase in morning and evening PEF was observed.
- The incidence of side effects increased with higher doses, leading to two withdrawals.
Conclusions:
- Continuous oral treatment with sustained-release terbutaline sulphate, even at high doses, does not provide clinically useful protection against exercise-induced asthma in children.
- The observed side effects at higher doses suggest a limited therapeutic window for this formulation in managing EIA.
Abstract:
We wanted to assess the protective effects on exercise-induced asthma as well as the clinical efficacy and safety of increasing doses of a new sustained-release formulation of terbutaline sulphate, in 17 asthmatic children aged 6-12 yrs (mean 9 yrs). Placebo, 2, 4 and 6 mg terbutaline were given b.i.d. for 14 days, in a randomized, double-blind, cross-over design. At the end of each two week period, an exercise test was performed and plasma terbutaline was measured. Compared with placebo, no significant effect was seen on asthma symptoms monitored at home, or on exercise-induced asthma. The percentage falls in FEV1 after the exercise test were 36, 35, 27 and 28%, after placebo, 4, 8 and 12 mg terbutaline.day-1, respectively. There was no correlation between plasma terbutaline and dose of terbutaline. A small but statistically significant dose-related increase in morning and evening peak expiratory flow (PEF) recordings occurred, but the incidence of side-effects also increased with the dose given. There was a trend towards more side-effects when the high doses were used, and two patients withdrew from the study because of side-effects at this dose. It is concluded that continuous treatment, even with high doses of oral terbutaline, does not offer clinically useful protection against exercise-induced asthma.