If anyone reading this is interested in inventing chemicals that alter the way the human brain works, I've got an idea: an anti-rape drug.

Some rapes are triggered by lust/horniness, and others are triggered by anger or hatred. This drug targets the latter.

There is a part of the brain that behaves a certain way when a person feels anger or hatred. There is also a part of the brain that behaves a certain way when a man gets an erection. So what the anti-rape drug would do is prevent the erection part of the brain from working when the anger/hatred part of the brain is active.

How to get people to take this drug?

1. Require sex offenders to take it on a regular basis as a condition of parole.
2. If you don't want your army raping people, require your army to take it. (Plausible for some armies, not for others)
3. Put a sniffable version in pepper spray.
4. Require it to be added to viagra.
5. Require it to be added to steroids.
6. When a version is perfected without side effects, dump it in the world's drinking water!

This doesn't address lust-related rape, but it could at least cut down on rape as hate crime.