Naloxone is an opiate-receptor blocker that is thought to improve spinal blood flow in SCI patients (Flamm et al. 1985). Animal models of acute SCI have shown that naloxone effectively reduces ischemia and promotes neurological recovery (Faden et al. 1981a, 1981b; Young et al. 1981). One early phase-one clinical trial deemed naloxone to be safe when administered to patients with acute SCI (Flamm et al. 1985).