2 research outputs found

    4ā€‘Amino-7,8-dihydro-1,6-naphthyridin-5(6<i>H</i>)ā€‘ones as Inhaled Phosphodiesterase Type 4 (PDE4) Inhibitors: Structural Biology and Structureā€“Activity Relationships

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    Rational design of a novel template of naphthyridinones rapidly led to PDE4 inhibitors with subnanomolar enzymatic potencies. X-ray crystallography confirmed the binding mode of this novel template. We achieved compounds with double-digit picomolar enzymatic potencies through further structure-based design by targeting both the PDE4 enzyme metal-binding pocket and occupying the solvent-filled pocket. A strategy for lung retention and long duration of action based on low aqueous solubility was followed. <i>In vivo</i> efficacies were measured in a rat lung neutrophilia model by suspension microspray and dry powder administration. Suspension microspray of potent compounds showed <i>in vivo</i> efficacy with a clear doseā€“response. Despite sustained lung levels, dry powder administration performed much less well and without proper doseā€“response, highlighting clear differences between the two formulations. This indicates a deficiency in the low aqueous solubility strategy for long duration lung efficacy
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