Alien narcotics would probably be phenomenal.
One thing I never understood, is when McCoy changed history, and Starfleet as we know it never existed, the Enterprise never existed, etc. then Kirk and Spock and the landing party would never have been on that planet with the time portal. So they wouldn’t have been in a position to go back in time themselves to change history back to what it should have been.
Maybe I’m missing something. Of course, based on that idea I just noted, then there’s no storyline for the episode.
It was always my understanding that Kirk went back and stayed becoming a police officer first then the founding partner of a prestigious Boston law firm before contracting Mad Cow Disease and dying.
Dr. Who had a serial about narcotics and an addicted navigator.
https://en.m.wikipedia.org/wiki/Nightmare_of_Eden
It’s a favorite from the Baker era.
Had I known that a large piece of liver could make us see into the past, I might have eaten more of it.
Great article on the famous Star Trek episode, ‘City on the Edge of Forever’ and the original Harlan Ellison treatment.