I was wondering about this just yesterday, I think I either posted about it too on another topic or just wrote it and never posted... but anyway, personally I'm really intrigued about IV nicotine. I know what tobacco/nicotine does to my body when taken orally, sublingually, vaporized, smoked or transdermally. I'm especially interested in the differences of various tobacco vs. pure nicotine, I've made some interesting observations about absorption and effects that have taught me a lot about myself and pharmacology in general. For me doing a drug IS studying pharmacology... It doesn't feel weird to me at all that one would want to inject nicotine, although it is a bit strange topic on a harm reduction forum.
Let's just try to be as safe as possible as learn as much as possible okay? As for the dosage, someone said something along the lines "...that would be like smoking a whole cigarette in 5 seconds" I just have to comment that, I sometimes dry a whole cigarette completely, grind it to fine powder, mix it with cannabis and use a gravity bong to get it all in my lungs in under 5 seconds. It's really interesting how radically the effects are this way when compared to, say a nicotine patch that has over 20x more the amount of nicotine. Wasn't Shulgins tip on dosing for the first time (though he was working with virtually unknown substances at that point) "to take the least amount of powder that you think could possibly have an effect and then halve that" or something. Personally I think 50mcg sounds like a safe dose to start, but you never know.
And honestly, I believe people inject far more hazardous things than pure nicotine, it's unusual yes and we don't know much about what's going to happen, but can it honestly be as dangerous as, say, injecting impure methamphetamine? And this is only in the name of science anyway, right?