Comparison of RPL554 With Placebo and Salbutamol in Asthmatic Patients

A seven way crossover study to investigate the pharmacodynamics, pharmacokinetics, safety and tolerability of inhaled RPL554 compared to salbutamol and placebo in patients with mild to moderate chronic asthma. Salbutamol is a marketed beta-2 agonist typically used to treat bronchospasm (due to any cause, allergen asthma or exercise-induced), as well as chronic obstructive pulmonary disease but has associated dose-related systemic side effects. RPL554 is a dual PDE3 and PDE4 inhibitor that has bronchodilatory and anti-inflammatory actions and also the potential to stimulate increases in mucociliary clearance via its proven ability to activate CFTR. Four different doses of RPL554 will be compared with placebo and a two doses of salbutamol as benchmarks for bronchodilation and systemic side effects.