When I have injected methadone, I thought that I needed to do at least 30-40mg per shot, because 30mg seems to be my threshold for getting somethign that resembles a rush, so at those doses and above I got a slight rush and it would really hold me well. However the rush is not a heroin type rush - it is more of a 'ahhh, finally my receptors are saturated' rush, a releif rather than a rush. When IV'ing methadone, it seems the half-life is greatly compromised. This is perhaps due to fact that there is latent release of methadone from fat tissue when ingested orally, making it last longer, whereas when injected in goes straight to the receptors and then there is nothing left in the depots of your body (pure guessing here). But 3-4 hours in after a shot I would get really groggy or tired, and since then I have figured out that low doses spaced throughout the day hold me much better. So when that was realized, there was absolutely no reason to IV, as at 2.5-5mg doses there is absolutely no rush, just a quick onset, maybe half an hour quicker than the oral peak. So just eat the dones. If you must try to IV, try it once or so, but be safe, guage your own threshold level by starting low. You will soon realize it is nothing but a needle fixation that makes you want to IV the methadone, and nothing to do with onset/BA or otherwise.
