I think that while there certainly is a physical aspect of the addiction, the ego part is right, too - and so it stands that if the ego has strong mental, emotional, etc connections to the experience/addiction/reasons for addiction, then transforming the ego could be of huge help, right?
I've heard many good things about ayahuasca being used for hard drug addictions, and I think this has something to do with it.
Imagine - the chemistry between you and, say, a romantic partner is similar to the chemistry between baking soda and vinegar - it foams and fizzes and reacts for a while - then it's over. The partners get bored and want new things. Their initial reaction with each other is over, and not only that, but the relationship they had together actually changed their individual composition so that they are now neutral to each other - no more fizzing - so they're ready to find new partners that will react strongly with their 'new' chemical makeup.
But if they just stay together, they're going to need to find other ways to feel the fizzing and foaming - they may use TV, drugs, food, partners on the side, etc - but they remain stuck in that chemical equation with their old partner, and so the ego - their chemical composition - remains largely unchanged and so they keep needing to find new things, or just surrender and accept a boring sedentary life, like many married couples end up doing.
But if an ego is constantly being reshaped, reformed, developed, torn down and rebuilt, transformed, etc etc etc - which involves a connection to source between all tear-downs and rebuilds - it can do wonders for rejuvenating one's experience of life and desire to break old patterns and experience new things, become a new person that can feed ravenously off of new, healthy things, rather than sticking with one strong form of explosive energy because the ego knows nothing else will do, all the while ultimately limiting you.
And I think psychedelics in general are good at helping with this - they can tear your ego down and break away the old patterns, grooves, ridges, and leave you with a fresh new slate.
Obviously not all experiences of this nature transform someone's life...but I think it's a valid method that definitely works for some...whether or not my perception of how/why it works is anywhere near accurate. I think the way in which it's done can have a big part in it...for example, doing it in the living room where you are always at and hoping for drastic change and transformation probably isn't going to be as effective as removing yourself from your regular habits, routine, places, etc - taking yourself out of your comfort zone - and then doing it. I think this would be much more powerful/hold much more potential.
And I think that a very important thing to note here is that you have to want to do it - OR - acknowledge that you
don't want to do it and just use your willpower to STILL go through with it, knowing that just because your ego doesn't want to change doesn't mean that you can't still take the wheel and steer your whole self towards a healthier life by ignoring the cries of the ego and charging forward in a new direction - eventually, through this, your ego
will change and develop new thirsts/hungers.
Best wishes to you - I know nothing about heroin addiction; these are just some thoughts that your post sparked so I wanted to share. Much love.