Abstract: N-substituted azetidinones are a class of inhibitors of human leukocytes elastase which are known to be useful in the treatment of a wide variety of antiinflammatory and antidegenerative diseases. In inhibiting elastase, the therapeutic agents are shown to form a characteristic stable complex with the enzyme. In the assay disclosed herein, the inhibitor-enzyme complex is advantageously hydrolyzed and specific product(s) of the hydrolysis are measured. The assays are useful in a clinical setting, for determining appropriate dosage and assessing the effectiveness of treatment.

Abstract: N-substituted azetidinones are a class of inhibitors of human leukocytes elastase which are known to be useful in the treatment of a wide variety of antiinflammatory and antidegenerative diseases. In inhibiting elastase, the therapeutic agents are shown to form a characteristic stable complex with the enzyme. In the assay disclosed herein, the inhibitor-enzyme complex is advantageously hydrolyzed and specific product(s) of the hydrolysis are measured. The assays are useful in a clinical setting, for determining appropriate dosage and assessing the effectiveness of treatment.

Abstract: Disclosed are .beta.-lactams of formula I ##STR1## wherein X is a chromogenic or fluorogenic substituted aryl or heteroaryl, which are specific inhibitors of Human leukocyte elastase (HLE). Upon contact with HLE these compounds are cleaved to form a chromogenic or fluorogenic species which may be readily measured by the assay disclosed herein. The assay thus provides a means for direct measurement of the amount of active HLE in a body fluid or other sample.