> On the other hand, nicotine is something like 19 times as addictive as heroin...

Nicotine or smoking?

(I think the '19 times as addictive' is calculated on the basis of people trying to give up smoking / taking heroin and rates of success with total abstinence)

If it was nicotine that was addictive rather than the method of delivery then people shouldn't have trouble substituting smoking for the equivalent dosage of nicotine in patches, gum, or sprays.