In this Instructable, talbotron22 shows how to make “Kitty Crack,” an ultra-potent catnip extract containing nepetalactone, catnip’s active ingredient. One pound of catnip yielded 143mg of nepetalactone.
A note about safety. Yes, it is safe to use this extract on cats. I have looked into it, and there are a number of studies (very interesting in their own right) using pure nepetalactone on cats in experiments trying to figure out why it causes them to go bonkers. The upshot is that it’s pretty safe….