There has been a long history of scientist experimenting on themselves. In 1964, Jack Barnes stung himself to prove that the jellyfish Carukia barnesi could cause the incredibly painful Irukandji syndrome. Barry Marshall drank a culture of H. pylori to convince his peers that it was the cause of stomach ulcers. Though please don’t try this at home, there are reasons there are tight ethical controls in place for testing and research.
Cats usually seem to know when too much catnip is enough. If they eat too much it tends to cause vomiting & diarrhea. So it’s best not to give them too much. Although with the high sugar content, it’s probably worse to feed them marshmallows.
Dr Mad: It took many years, but I hold in my hand a refined form of pure catnip!
Prof Panda: You're not going to eat that before you test it are you?
Dr Mad: Hee Hee
Dr Mad: NOM NOM NOM NOM NOM NOM NOM NOM
SFX: PAW PAW
Marshmallow Prof Panda: Are you ok? You don't look so good.