Yes Junkies rat out everyday in holding cells. This called rolling up. They grab an addict for simple possession get him to call his dealer.
Pretty sure we’ve all been there where we would do anything to get better. Especially 24 hours in.
Sounds really unpractical. I mean sure, if you have to interrogate a junkie, I guess it's an option, but really depends if he's progressed to taking every day, otherwise this just isn't very solid. Getting a complete naive dependant sounds like LOTS of work. It's just rather dumb. Sounds like a TV idea, exploding cars from gunshots, pistols without recoil, bad guys never hitting anything, pretty much that area.
If I had to torture someone, I'd go for MDMA and then just apply pain. Heroin, to my logic, sounds stupid. Too many factors. I've experienced pain on MDMA, and it's fucking intense. I think that'll do.
Melamine maybe. Forces movement shut, increased pain.