I still have some northern. I bought some couple years ago, told I was going to blow up, it was “real” gear, paid way too much as well from a friend.
I was running what I knew was underdosed BT at the time (didn’t care, just using it up) and I noticed no difference when I switched to Northern, so after a vial I just went on to be better brand when I was gearing up to cycle.
Mind you Northern might be ok now, but I’ll leave that judgment up to the people who know better than me.
It’s funny I still have a couple vials of BT and a couple of Vortex, BT’s alter ego, and a couple northern that I just keep around in case I can’t get any gear at some point 20 years from now, lol.
I’d use it, but I don’t want t waste a blood test to figure out how underdosed it is, so I know how much to take, lol.