The discovery that a main neuroprotective function of MP is due to its lipid peroxidase action instead of its glucocorticoid receptor action initiated the development of steroid analogues that were mechanistically similar but did not cause associated side-effects. One such drug, tirilazad mesylate, was especially effective for recovering neural function in spinal cord injured animal models (e.g., Anderson et al. 1988; Hall, 1988; Holtz & Gerdin, 1991, 1992). Like MP, tirilazad mesylate inhibits lipid peroxidation and stabilizes neuronal membranes by scavenging oxygen free radicals. Tirilazad mesylate incorporates into the membrane lipid bilayer, where it restricts the movement of free oxygen radicals and prevents them from spreading to neighbouring nerves (Kavanagh & Kam, 2001). In a large RCT of tirilazad mesylate used in head injured individuals, this pharmaceutical agent was shown to have no effect on recovery after six months compared to placebo (Marshall et al. 1998). Only one clinical trial has examined the effectiveness of tirilazad mesylate in acute SCI (Bracken et al.1997), where its neuroprotective benefits were compared to those of MP.