The Heroin-Coathanger scene. Not realistic at all.

In college I was into the party scene quite a bit and I have done harder drugs. That whole scene was ridiculous.

If you cut yourself like that you would bleed out and the heroin would be pushed out by your blood.

In a pinch with no "hardware" what someone would be far more likely to do is make "monkey water"

Basically they would heat up the heroin, mix it with water, and snort it up their nose like nasel spray.

That would be much much more effective as it hits the blood stream right away, not as effective as intervenious but still it would work much better then *beep* stabbing yourself with a hanger which as I pointed out above wouldnt work at all.