My buddy has an extremely high opiate tolerance. Started with pain killers, and eventually graduated onto H, and then finally IV. He's at the point where he uses large amounts intravenously 3-5 times a day, and gets absolutely no effect from it other than relieving his withdrawals. Now onto the question... He began using Cocaine occasionally a couple months back, and noticed that he seemed to get all of the amphetamine effects of it, IE: Alertness, Staying awake for hours, lots of energy, sometimes rapid heartbeat, anxiety, and feeling extremely racy, depending on how much and what the quality was. However, he has yet to get even the slightest bit of euphoria from it, no matter how much he takes or what the supposed quality was. Does this have to do with the fact that he can no longer get euphoria from H as well? I know cocaine reacts with your dopamine receptors, so did the H burn out his dopamine receptors to the point that it doesn't matter what the substance is, the receptors are just shot? Then on the other hand, just the other day he was able to get some stuff from a different source, and he noticed immediately after doing the first 2 lines that he was hit with extreme euphoria which lasted about 20 minutes. I don't know what was different about this particular batch, but ever since that happened he has gone to this new source several times and never had the same results again. So what was so special about this one time from this one source? I guess I'm just trying to determine if everything he's getting is just garbage, and that's why he feels nothing? And maybe this one batch was extremely good quality? Or if his dopamine receptors are shot from the H, and this particular batch was cut with something different this time like mdma or something? Any insight would be appreciated Thanks!