Earlier quoted context omitted.
I'd be interested to see some stats on IV heroin use and rate of addiction if you've got some
why would the route of administration have anything to do with that? it's the same substance hitting the same receptors. every single addiction takes effort and time to develope, even heroin. anyway, google 'heroin + medical use' and be very suprised.
In terms of addictive potential for any given drug:
smoking > injecting > snorting > eating > topical
If you were to actually compare drinking crack with drinking coffee, the addictiveness of both would be identical.