Vol. 302, Issue 1, 127-137, July 2002

Pharmacology of N-(3,5-Dichloro-1-oxido-4-pyridinyl)-8-methoxy-2-(trifluoromethyl)-5-quinoline Carboxamide (SCH 351591), a Novel, Orally Active Phosphodiesterase 4 Inhibitor

M. Motasim Billah, Nicola Cooper, Michael Minnicozzi, Julie Warneck, Peng Wang, John A. Hey, William Kreutner, Charles A. Rizzo, Sidney R. Smith, Simon Young, Richard W. Chapman, Hazel Dyke, Nang-Yang Shih, John J. Piwinski, Francis M. Cuss, John Montana, Ashit K. Ganguly and Robert W. Egan

Schering-Plough Research Institute, Kenilworth, New Jersey (M.M.B., M.M., P.W., J.A.H., W.K., C.A.R., S.R.S., S.Y., R.W.C., N.Y.S., J.J.P., F.M.C., A.K.G., R.W.E.); and Celltech Chiroscience Ltd., Cambridge, United Kingdom (N.C., J.W., H.D., J.M.)

N-(3,5-Dichloro-1-oxido-4-pyridinyl)-8-methoxy-2-(trifluoromethyl)-5-quinoline carboxamide (SCH 351591) has been identified as a potent (IC₅₀ = 58 nM) and highly selective type 4 phosphodiesterase (PDE4) inhibitor with oral bioactivity in several animal models of lung inflammation. N-(3,5-Dichloro-4-pyridinyl)-8-methoxy-2-(trifluoromethyl)-5-quinoline carboxamide (SCH 365351), the only significant in vivo metabolite, is also a potent and highly selective PDE4 inhibitor (IC₅₀ = 20 nM). Both SCH 351591 and SCH 365351 inhibited cytokine production in human blood mononuclear cell preparations. Oral SCH 351591 significantly attenuated allergen-induced eosinophilia and airway hyperreactivity in allergic guinea pigs at doses as low as 1 mg/kg. In this model, oral SCH 365351 showed similar potency. When SCH 351591 was administered orally to allergic cynomolgus monkeys at 3 mg/kg, Ascaris suum-induced lung eosinophilia was blocked. Hyperventilation-induced bronchospasm in nonallergic guinea pigs, a model for exercise-induced asthma, was also suppressed significantly by oral SCH 351591 at 0.3 mg/kg. Cilomilast (SB 207499; Ariflo), a PDE4 inhibitor currently being developed for asthma and chronic obstructive pulmonary disease (COPD), was 10- to 30-fold less potent than SCH 351591 at inhibiting guinea pig lung eosinophilia and hyperventilation-induced bronchospasm. In a ferret model of emesis, maximum nonemetic oral doses of SCH 351591 and cilomilast were 5 and 1 mg/kg, respectively. Comparison of plasma levels at these nonemetic doses in ferrets to those at doses inhibiting hyperventilation-induced bronchospasm in guinea pigs gave a therapeutic ratio of 16 for SCH 351591 and 4 for cilomilast. Thus, SCH 351591 exhibits a promising preclinical profile as a treatment for asthma and COPD.