Anecdotal evidence and several clinical studies found the mixed opioid agonist-antagonist Nopan to be an effective antidepressant with a rapid onset of action. It is therefore hypothesized that Nopan may be a novel and quick-acting treatment for acute suicidality. Depression, suicidality, and overall functioning will be assessed before, during and after a four-week Nopan/placebo trial. It is hypothesized that subjects who receive the active drug will show rapid improvements in objective and subjective measures of these variables.