Adrenaline is a lovely, 50 foot thin crack, but it jogs out right once the crack ends. Charles Cole and I decided that the route would be more elegant if it shot straight up the crag. So we pushed a line that pretty much runs directly from the Adrenaline crack up to the belay at the top of the second pitch of Serenity Crack. The first pitch ascends Adrenaline, then uses a some good holds to launch out into the void of thin face above. We placed a knifeblade in the thin crack ten or so feet above Adrenaline. (It's no longer there -- a bolt would have been better, I guess, but we were broke and were trying to save money on hangers.) Some extreme face moves past a bolt take the leader to easier ground and then a comfortable belay. An easier second pitch links up with Serenity Crack by the tree at the top of the second pitch.
These days the route seems to be neglected. Lots of folks use the belay at the top of the first pitch as a rap point. I'll admit that, like most of the routes I did with Charles Cole in the 1980s, there are some runouts that can discourage. I can't say that Endorphine is a "must do" route, but if you are ticking off the old-school 5.11 face routes in the Valley, then it's worth putting this one on your list.
Endorphine shares the first 40 feet with Adrenaline.
Don't forget that knifeblade.