Let's take a step back and look at what we've learned about the mechanisms of neuronal injury after brain ischemia. In particular, note how some pathways either feed back on themselves or contribute to other pathways.

Figure: Total Train Wreck. Mechanisms of damage after transient brain ischemia. And remember: this is a cartoon--a gross oversimplification. As always, reality is a lot messier.

When you put it all together, you can reach several conlcusions. Brain ischemia is horribly complex, and initiates a cascade of interlocked cytopathological processes that inflict cellular damage on multiple organelles by multiple mechanisms. And from there, it doesn't take a leap of logic to conclude that single drug therapy will never work.