The present invention relates to a diketohydrazine derivative of formula (I)and apharmaceutically acceptable salt thereof (the symbols in the formula have thesamemeaning as described in the specification).(see formula I)The compound of formula (I) has an inhibitory activity against cysteineprotease,and it is useful for the treatment of inflammatory diseases, immune diseases,ischemic diseases, respiratory diseases, circulatory diseases, blood diseases,neuronaldiseases, hepatic or biliary diseases, osseous or articular diseases,metabolic diseases,etc. And the compound has inhibitory activity against elastase and it is alsousefulfor the treatment of COPD (chronic obstacle pulmonary diseases).
