We are performing late Phase I and Phase II studies of naloxone in treatment of patients with acute cerebral ischemia. The late Phase I study will evaluate the efficacy and potential side effects of esculating doses of naloxone. The PhaseII study will evaluate the efficacy of an optimal dose of naloxone in treating patients with acute ischemic cardiovascular disease. If the results of the Phase I and Phase II trials suggest that large doses of naloxone are effective, then a randomized double blind trial could be performed.