Roflumilast is a specific phosphodiesterase type (4PDE4) inhibitor indicated for use as a treatment to reduce the risk of COPD exacerbations in patients with severe COPD associated with chronic bronchitis and a history of exacerbations.

CHF6001 is a phosphodiesterase 4 (PDE4) inhibitor optimised for inhaled delivery and tolerability, for the treatment of Asthma and Chronic Obstructive Pulmonary Disease. CHF6001 was 7- and 923-fold more potent than roflumilast and cilomilast, respectively, in inhibiting PDE4 enzymatic activity. CHF6001 inhibited PDE4 isoforms A-D with equal potency, showed an elevated ratio of high-affinity rolipram binding site versus low-affinity rolipram binding site and displayed >20,000-fold selectivity versus PDE4 compared with a panel of phosphodiesterases. CHF6001 effectively inhibited the release of tumor necrosis factor-α from human peripheral blood mononuclear cells, human acute monocytic leukemia cell line macrophages (THP-1), and rodent macrophages (RAW264.7 and NR8383). CHF6001 has the potential to be an effective topical treatment of conditions associated with pulmonary inflammation, including asthma and chronic obstructive pulmonary disease.