Cilomilast (SB-207499) is a potent, selective and orally active inhibitor of Phosphodiesterase 4 (PDE4), with IC50s of ~100 and 120 nM for LPDE4 and HPDE4, respectively. Cilomilast shows selectivity for PDE4 over PDE1, PDE2, PDE3 and PDE5 (IC50=74, 65, >100, and 83 µM, respectively). Cilomilast has anti-inflammatory and immunomodulatory effects and can be used for thr research of asthma and chronic obstructive pulmonary disease (COPD)