Cilomilast (INN,[1] codenamed SB-207,499, proposed trade name Ariflo) is a drug which was developed for the treatment of respiratory disorders such as asthma and chronic obstructive pulmonary disease (COPD).

[2] Phosphodiesterase (PDE) inhibitors, such as theophylline, have been used to treat COPD for centuries; however, the clinical benefits of these agents have never been shown to outweigh the risks of their numerous adverse effects.

It showed reasonable efficacy for treating COPD, but side effects were problematic and it is unclear whether cilomilast will be marketed, or merely used in the development of newer drugs.

[3][4] Cilomilast is a second-generation PDE4 inhibitor with anti-inflammatory effects that target bronchoconstriction, mucus hypersecretion, and airway remodeling associated with COPD.

GlaxoSmithKline (GSK) filed for drug approval with the U.S. FDA at the end of 2002 and in January 2003 with the European Medicines Evaluation Agency (EMEA).