Opinions - Is it possible? Just Once?

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Swim has always wanted to do heroin. Is it possible to do this drug once and never do it again? He doesn't have an addictive personality at all. Some say nicotine is more addicting, and he has quit that after smoking for three years. He has done Coke, oxy's, vicodin, morphine and he hasn't had any problem with addiction to those and he has done quite a bit of each. Never went thru any serious withdrawals from the opiates. He doesn't plan on doing it more than once unless withdrawal symptoms are minimal.
So, is it even possible to shoot up once or is SWIM guaranteed to be an addict even with a non-addictive personality?