In vivo efficacy in airway disease models of roflumilast, a novel orally active PDE4 inhibitor.
We have investigated the bronchodilator and anti-inflammatory properties of roflumilast (3-cyclopropylmethoxy-4-difluoromethoxy-N-[3,5-dichloropyrid-4-yl]-benzamide), a novel, highly potent, and selective phosphodiesterase 4 (PDE4) inhibitor. Additionally, we compared the effects of roflumilast and its N-oxide, the primary metabolite in vivo, with those of the PDE4 inhibitors piclamilast, rolipram, and cilomilast. Roflumilast inhibited the ovalbumin-evoked contractions of tracheal chains prepared from sensitized guinea pigs (EC(50) = 2 x 10(-7) M) but showed no relaxant effect on tissues contracted spontaneously. In spasmogen-challenged rats and guinea pigs, intravenously administered roflumilast displayed bronchodilatory activity (ED(50) = 4.4 and 7.1 micromol/kg, respectively). Furthermore, roflumilast dose dependently attenuated allergen-induced bronchoconstriction in guinea pigs (ED(50) = 0.1 micromol/kg i.v.). Roflumilast given orally (ED(50) = 1.5 micromol/kg) showed equal potency to its N-oxide (ED(50) = 1.0 micromol/kg) but was superior to piclamilast (ED(50) = 8.3 micromol/kg), rolipram (ED(50) = 32.5 micromol/kg), and cilomilast (ED(50) = 52.2 micromol/kg) in suppressing allergen-induced early airway reactions. To assess the anti-inflammatory potential of orally administered roflumilast, antigen-induced cell infiltration, total protein, and TNFalpha concentration in bronchoalveolar lavage fluid of Brown Norway rats were determined. Roflumilast and its N-oxide equally inhibited eosinophilia (ED(50) = 2.7 and 2.5 micromol/kg, respectively), whereas the reference inhibitors displayed lower potency (ED(50) = 17-106 micromol/kg). Besides, orally administered roflumilast abrogated LPS-induced circulating TNFalpha in the rat (ED(50) = 0.3 micromol/kg), an effect shared by its N-oxide, with both molecules exhibiting 8-, 25-, and 310-fold superiority to piclamilast, rolipram, and cilomilast, respectively. These results, coupled with the in vitro effects of roflumilast on inflammatory cells, suggest that roflumilast represents a potential new drug for the treatment of asthma and chronic obstructive pulmonary disease.
Department of Pharmacology, Byk Gulden, P.O. Box 10 03 10, 78403 Konstanz, Germany. daniela.bundschuh@byk.de
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Bundschuh
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Eltze
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Barsig
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Wollin
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Hatzelmann
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Beume
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000284:Administration, Oral; D000631:Aminopyridines / Q000627:therapeutic use; D000818:Animals; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use*; D001549:Benzamides / Q000627:therapeutic use; D016084:Bronchoconstriction / Q000187:drug effects; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D003521:Cyclopropanes; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D008070:Lipopolysaccharides / Q000494:pharmacology; D008173:Lung Diseases, Obstructive / Q000188:drug therapy*; D008297:Male; D010047:Ovalbumin / Q000276:immunology; D010726:Phosphodiesterase Inhibitors / Q000627:therapeutic use*; D051381:Rats; D011914:Rats, Inbred BN; D017207:Rats, Sprague-Dawley; D014132:Trachea / Q000187:drug effects / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D000631:Aminopyridines; D018927:Anti-Asthmatic Agents; D001549:Benzamides; D003521:Cyclopropanes; D008070:Lipopolysaccharides; D010726:Phosphodiesterase Inhibitors; D014409:Tumor Necrosis Factor-alpha; C424423:Roflumilast; D010047:Ovalbumin; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4