ASP3258, an orally active potent phosphodiesterase 4 inhibitor with low emetic activity

We investigated the pharmacology of a novel phosphodiesterase (PDE) 4 inhibitor, ASP3258 (3-[4-(3-chlorophenyl)-1-ethyl-7-methyl-2-oxo-1,2-dihydro-1,8-naphthyridin-3-yl] propanoic acid), comparing its potency with that of the most advanced PDE4 inhibitors, roflumilast and cilomilast. PDE4 inhibition by ASP3258 (IC50 = 0.28 nM) was as potent as that achieved with roflumilast. ASP3258 inhibited lipopolysaccharide-induced tumor necrosis factor (TNF)-α production in rat whole blood cells (IC50 = 8.8 nM) and rat alveolar macrophages (IC50 = 2.6 nM). Orally administered ASP3258, roflumilast, and cilomilast dose-dependently inhibited production of interleukin-4, TNF-α, and cysteinyl leukotrienes, as well as leukocyte infiltration in bronchoalveolar lavage fluid from the airways of ovalbumin-sensitized Brown Norway rats, and these compounds showed almost complete inhibition at doses of 3, 3, and 30 mg/kg, respectively. PDE4 inhibitors induce emesis by mimicking the pharmacological action of α2-adrenoceptor antagonist. However, orally administered roflumilast (3 mg/kg) and cilomilast (10 mg/kg), but not ASP3258 (3 mg/kg), inhibited α2-adrenoceptor agonist-induced anesthesia in rats and induced emesis in ferrets. Although ASP3258 (3 mg/kg) inhibited airway inflammation completely, it had no emetic activity. As such, this compound may be useful in treating airway inflammatory diseases such as asthma and COPD.