the present invention relates to certain substituted oxadiazole , thiadiazole and triazole peptoids which are useful as inhibitors of human neutrophil elastase for the treatment of hne - mediated processes implicated in conditions such as adult respiratory distress syndrome , septic shock and multiple organ failure . a series of studies also have indicated the involvement hne in myocardial ischemia - reperfusion injury , emphysema . hne - mediated processes are implicated in other conditions such as arthritis , periodontal disease , glomerulonephritis , dermatitis , psoriasis , cystic fibrosis , chronic bronchitis , atherosclerosis , alzheimer &# 39 ; s disease , organ transplantation , corneal ulcers , and invasion behavior of malignant tumors .