No, it just had a very potent effect once we placed it on the floor near them. Particularly on the male who was the larger, dominant cat of the house. There were two mature siblings from the same litter, a large male and petite female.
They were both excited as usual at first, but then the male became very aggressive. Ferociously, with all his claws out, he hunkered low straddling the sprig, digging all claws deep into the carpet while systematically ripping every bud from the sprig using his mouth, and eating them.
The female ran to the furthest bedroom and hid.
He foamed from the mouth, and became somewhat feral for the next ~20 minutes. Not towards the people, just kind of on display to nobody in particular. It was fascinating to watch.
I don't have the words to describe what happened. We'd given the cats dried catnip before, but this was an entirely different situation.
If you want to give your cats catnip, fresh stuff is definitely worth getting.