Krokodil. Homemade drug in Russia, Alternative to heroin, rotting it's users alive.

[Colonel Flagg]

I feel like Walter White - if you're going to do this shit, do it right. Recrystallize the organic drug in methanol, then purify the crap out of it through sublimation. Get the melt point to within <1° of the literature value, THEN it's OK to use. THe "flesh eating" side effect is from the phosphorus that's left behind after the garage synthesis from codeine.