A comparison of the clinical and bronchodilating effects of plain and slow-release tablets of terbutaline at steady state.

The clinical efficacy, the bronchodilating effect and the side effects of two oral forms of terbutaline were compared in a double-blind, cross-over study involving ten patients with chronic reversible airways obstruction. The administration of plain-tablets, containing 2.5 mg terbutaline sulphate, three times daily at 6 h intervals was compared to the administration of slow-release (SR) tablets, containing 5 mg terbutaline sulphate, every 12 h. Each course of treatment lasted for 7 days. Treatment with SR-tablets resulted in significantly higher lung function values in the morning (PEFR at home and FEV1 at the lung function laboratory on day 7). There were no significant differences between the two forms with regard to symptom score, extra use of rimiterol aerosol, heart rate or blood pressure. The plasma terbutaline concentration in the morning of the seventh treatment day was significantly higher during SR-tablet treatment. The plasma terbutaline concentration curve showed a smaller peak/trough ratio for the SR-tablets.