Yeah, I've come across some amps of ATP now and again. I really wouln't know what to use em for. A couple boys said the shot the stuff and it burned like all hell... though afterwards they could maintain a good hard contraction in the muscle they shot without too much trouble at all. I don't know how much I believe that... but yeah.
I would imagine that you'd be better off shooting it subcutaneously instead of intramuscularly. You'll probably see a very similar effect to Syntheselen... as it's ATP based as well.