The problem with this question is, what potentiation is one really looking for?
I ask because you could be asking: what combinations potentiate the palliative effects of opiates?
Or: what combinations potentiate the euphoric effects of opiates?
Or: what combinations potentiate the depressant/intoxicating effects of opiates?
The answers are mostly different for each question...
I'm not going to get into the palliative enhancement, because we're not on this site for that.
In terms of the euphoric effects of opiates, I would say hands down, you are looking at strong stimulants (cocaine, amphetamines, etc). There is a shit load of research that shows how the two (opiates and stimulants) are extremely synergistic, and produce far more dopamine (DA) release than either one by itself.
There really is not any other drug combination that produces more DA release than that of strong opiates and either cocaine or an amphetamine.
I guess the only thing to add on top of that is nicotine, which would even further the potentiation of the euphoric (and thus addictive) properties.
NOTE: Never combine cocaine AND amphetamine, only one or the other (and in terms of absolute DA release, cocaine--while its working--is the strongest, esp if you're using it IV or smoking). Cocaine and amphetamine actually work against each other (amphetamine needs to be taken up by the autotransporter (the reuptake receptor) which cocaine is occupying, thus adding the two is not only ineffective, but reduces absolute DA release overall).
Lastly, pretty much what everyone else has suggested is how to potentiate the depressant effects: benzos, barbituates, alcohol, antihistamines, etc.
However, SWIM honestly hate doing this. SWIM used to take H and benzos ALL the time. Thought it was nice, but that was before SWIM realized, that he could be MUCH higher and enjoy the opiate high more because he wouldn't be so tired and nodding out the whole time, which was especially the case when benzos, alcohol, or whatever was added. THEN swim learned in various college classes that in fact, these other depressant drugs actually DECREASE the amount of DA released! Yes, your are more fucked up, but you aren't as "euphorically high". This is because opiates work (in one way) by blocking GABA receptors and prevent release of GABA onto postsynaptic DA neurons (GABA release onto DA neurons acts to inhibit release). So when you take a drug that enhances the function of GABAergic neurons (alcohol, benzos, barbs, antihistamines, etc) you aren't letting the opiate do its job as well, so less DA is released.
Anyway, long story short, the question needs to be more specific. However, in SWIM's opinion, there is absolutely nothing like IV heroin + cocaine, with a cigarette afterwards for the cherry on top. (With that being said, that combo is literally the most addictive thing you could ever do. Unfortunately, it's lead to my demise time and time again, so please be careful out there guys and gals).
I ask because you could be asking: what combinations potentiate the palliative effects of opiates?
Or: what combinations potentiate the euphoric effects of opiates?
Or: what combinations potentiate the depressant/intoxicating effects of opiates?
The answers are mostly different for each question...
I'm not going to get into the palliative enhancement, because we're not on this site for that.
In terms of the euphoric effects of opiates, I would say hands down, you are looking at strong stimulants (cocaine, amphetamines, etc). There is a shit load of research that shows how the two (opiates and stimulants) are extremely synergistic, and produce far more dopamine (DA) release than either one by itself.
There really is not any other drug combination that produces more DA release than that of strong opiates and either cocaine or an amphetamine.
I guess the only thing to add on top of that is nicotine, which would even further the potentiation of the euphoric (and thus addictive) properties.
NOTE: Never combine cocaine AND amphetamine, only one or the other (and in terms of absolute DA release, cocaine--while its working--is the strongest, esp if you're using it IV or smoking). Cocaine and amphetamine actually work against each other (amphetamine needs to be taken up by the autotransporter (the reuptake receptor) which cocaine is occupying, thus adding the two is not only ineffective, but reduces absolute DA release overall).
Lastly, pretty much what everyone else has suggested is how to potentiate the depressant effects: benzos, barbituates, alcohol, antihistamines, etc.
However, SWIM honestly hate doing this. SWIM used to take H and benzos ALL the time. Thought it was nice, but that was before SWIM realized, that he could be MUCH higher and enjoy the opiate high more because he wouldn't be so tired and nodding out the whole time, which was especially the case when benzos, alcohol, or whatever was added. THEN swim learned in various college classes that in fact, these other depressant drugs actually DECREASE the amount of DA released! Yes, your are more fucked up, but you aren't as "euphorically high". This is because opiates work (in one way) by blocking GABA receptors and prevent release of GABA onto postsynaptic DA neurons (GABA release onto DA neurons acts to inhibit release). So when you take a drug that enhances the function of GABAergic neurons (alcohol, benzos, barbs, antihistamines, etc) you aren't letting the opiate do its job as well, so less DA is released.
Anyway, long story short, the question needs to be more specific. However, in SWIM's opinion, there is absolutely nothing like IV heroin + cocaine, with a cigarette afterwards for the cherry on top. (With that being said, that combo is literally the most addictive thing you could ever do. Unfortunately, it's lead to my demise time and time again, so please be careful out there guys and gals).