Eh, despite my doubts regarding the benefits of avoiding ejaculation (I think it's hooey. I'm guessing it's more of a psychological effect, that one has a fucked up mental tie between ejaculation and defeat/submission/termination of pleasure or whatever else and thus it's more obsessing about ejaculation that causes a problem as opposed to actual ejaculation. Blowing loads doesn't make you less of a man, and I'm pretty sure those who claim otherwise are just experiencing placebo) in my experience there are few narcotics that don't prolong the ability to hold off. As someone whose run the gamut from the strongest of opiates to the purest of meth I'm assuming there's some tie between the pleasurable effects of narcotics and prevention of ejaculation, which I'd probably hypothesize on further if I wasn't drunk and mentally lazy as hell right now.
On the other hand, some make you like sex more but prolong the whole thing, like the before mentioned meth, and some just kill everything in the area off, like opiates. I very good friend of mine used to get a boner every single time he'd do heroin (even if he wouldn't just say "I'm hard as a rock" I could see his ridiculous god damned boner straight through his shorts) but for most people, me included, yeah, it'll make it super tough to jizz but by the same token it'll also make you kinda just not that interested in sex and pretty unable to get it up. Amphetamines, in my experience, will make you a horny dog and help prolong the whole thing a little bit, but it tends to just inspire, uh...repeat episodes of ejaculation, if you will. Some stimulants, like cocaine, tend to kinda suck in multiple directions by making you horny but also draining all the blood from your junk.
So basically if your sole goal is preventing ejaculation opiates are probably going to be better, but if you just want to have great sex than something like meth or mcat is going to be better.
Or even better I'd not play around with incredibly addictive substances due to the unbelievably outdated belief that semen is heavily tied to male vigor and thus one should avoid ejaculation whenever possible. Beliefs like that tend to come and go, but you can trust me when I say shit like opiate addiction has a way of sticking around: take it from a drunk and slightly spun guy wearing nothing but boxers, socks, and a really tacky tie.
