GSK233705 (Darotropium bromide) is a muscarinic receptor antagonist used in conjunction with the prevention and treatment of chronic obstructive pulmonary disease (COPD) and asthma in humans.

Patients were randomized to receive 12.5 µg, 25 µg, 50 µg, 100 µg or 200 µg of GSK233705 or placebo once daily for 28 days. The primary endpoint was a change from baseline in trough forced expiratory volume in 1 s (FEV(1)) on day 29. RESULTS: The intent-to-treat population consisted of 576 patients (mean predicted FEV(1) 51%; mean age 62 years). Treatment with GSK233705 produced statistically significant improvements in pulmonary function compared with placebo. Only the 200 µg dose exceeded the predefined target threshold of 130-mL difference compared with placebo for the primary endpoint of change from baseline in trough FEV(1) on day 29. No clear pattern of dose-response was observed for the other doses. Serial FEV(1) (0-24 h) showed a peak effect around 2 h postdose and tended to decline to clinically insignificant levels compared with placebo at 23 and 24 h. Each dose of GSK233705 was well tolerated. The incidence of adverse events was low and similar across all treatment groups. There were no clinically significant effects on laboratory parameters, vital signs, or electrocardiograms. CONCLUSION: All doses of GSK233705 demonstrated bronchodilatory activity and were well tolerated. Although the onset of bronchodilation was rapid, it was not sustained over 24 h making it unsuitable for once-daily dosing.[2]