Bronchodilator Effect of RPL554 Administered in Addition to Tiotropium/Olodaterol in Patients With COPD

RPL554 is a dual inhibitor of phosphodiesterase 3 (PDE3) and phosphodiesterase 4 (PDE4) which are known to have a role in modulating the inflammatory airway response in respiratory diseases, including COPD. PDE3 inhibitors act as bronchodilators whilst PDE4 inhibitors have anti-inflammatory properties and there is also evidence to suggest that combined inhibition of PDE3 and PDE4 can have additive or synergistic anti-inflammatory and bronchodilator. The two doses of RPL554 (1.5 mg and 6 mg)have been selected based on the results from prior studies investigating single and multiple ascending doses in healthy subjects, single doses in asthmatics, single/multiple ascending doses in COPD patients, and 3 days of dosing in COPD patients. These doses were demonstrated to be both effective as a bronchodilator and well tolerated. The purpose of the study is to investigate if RPL554 has an additive bronchodilator effect when administered in combination with a commonly used anticholinergic/β-agonist combination medication, tiotropium/olodaterol (Respimat), in this patient population measured by the peak forced expiratory volume in one second (FEV1), and forced vital capacity (FVC).