That is what debriefing does, in reality. It lessens the impact of the trauma.
It's a very interesting study (to me) how the brain reacts (chemicals that imprint memory) when there is trauma. The sooner you can process the trauma, the easier it becomes for the brain to file it away like a normal memory.

I think taking it even after you have PTSD, for any additional upset or trauma might prevent being retraumatized or adding to the old memory problem? IDK Haven't read up on this area (medication) yet.