BAY-85-8501 is a selective, reversible and potent inhibitor of Human Neutrophil Elastase (HNE) , with an IC 50 of 65 pM. In Vivo In this model the exogenous HNE noxa is the primary cause of injury and lung hemorrhage. Based on picomolar potency against HNE as well as single digit potency versus MNE, BAY-85-8501 (29) completely prevents the development of lung injury and subsequent inflammation when administered 1 h prior to the HNE noxa. In the 0.01 mg/kg dose group, hemoglobin concentration is already significantly decreased. At a dose of 0.1 mg/kg, a significant effect on neutrophil count is observed. In this setup, efficacy is predominantly driven by potency against HNE (K i =0.08 nM). As the highly HNE-selective inhibitor BAY 85-8501 has no effect on PPE, BAY-85-8501 could not prevent the primary lung injury in this setup. Nevertheless, BAY-85-8501 could inhibit MNE, the endogenous driver of inflammation and secondary injury, although with decreased potency. Consequently, the effects of BAY-85-8501 on inflammation and secondary injury are weaker at this point, and only observed at 30-fold higher doses. Efficacy is predominantly driven by potency against MNE (K i =6 nM) in this second setup . MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:IC50: 65 pM (HNE)