Effect of oral slow-release terbutaline on early morning dyspnoea

Eight male patients with partly reversible airflow obstruction, who had a diurnal variation in peak expiratory flow rate (PEFR) of more than 20% were treated with placebo and slow-release terbutaline tablets (5 mg at 08.00 hours and 10 mg at 20.00 hours) for 8 days. On Day 8 of each period, PEFR and serum terbutaline were measured at 4 and 2-h intervals, respectively. PEFR on the terbutaline day showed a significant increase at 08.00, 12.00, 24.00, 04.00 and 08.00 hours as compared to the placebo day. Slow-release terbutaline prevented early morning dyspnoea. The serum concentration was 3.3 ng/ml during the day and 3.5 ng/ml during the night. During terbutaline therapy the patients reported fewer complaints than during the placebo period. It was concluded that slow-release terbutaline tablets are suitable for twice daily treatment.