My understanding was that kratom was more useful for harm reduction, rather than curing addiction, as it's still addictive but much less harmful than heroin.
It's similar to vaping or nicotine gum in that respect.
More precisely, there is a theory that nicotine becomes highly addictive in the presence of an MAOI which are naturally present in tobacco smoke, but not added to nicotine gum.
I was actually referring to inhalation vs ingestion; specifically how inhalation has a 10-20 second lag before the effects are noticeable whereas ingestion takes much longer - resulting in less behavioral reinforcement.
The MAOI theory is interesting, there are a lot of alkaloids in tobacco. Apparently nicotine uptake across alveoli membranes is very pH dependent - the ionic form won't cross the barrier. Cigarette smoke is cured at a high temp and has a low pH, pipe tobacco is cured at room temp and has a high pH. [0]
It seems that cigarettes are processed to specifically give a minimal dose per volume inhaled that quickly delivers nicotine as a way to maximize reinforcement behavior. I would be interesting to test the pH of commercial vaporization solutions.
It's similar to vaping or nicotine gum in that respect.