NA-184 is a selective and brain-penetrant calpain-2 inhibitor with an IC50 of 134 nM for mouse calpain-2. NA-184 has weak inhibitory activity on calpain-1 (IC50 of 2826 nM). NA-184 does not exhibit significant inhibition on a variety of other cysteine-, serine- or metallo-proteases. NA-184 shows significant neuroprotection and can be used for the study of traumatic brain injury (TBI).