Verona Pharma plc, a clinical stage biopharmaceutical company, researches, discovers, and develops therapeutic drugs to treat respiratory diseases primarily in the United Kingdom and North America. The company's lead product is RPL554, an inhaled dual inhibitor of the enzymes phosphodiesterase 3 and 4, which is in Phase IIa clinical trial that acts as a bronchodilator and an anti-inflammatory agent for the treatment of chronic obstructive pulmonary disease, cystic fibrosis, and asthma. Verona Pharma plc is based in London, the United Kingdom.