Dude don't knock those mouth and butt feels. Physical cues like that are often important signs of a drug "working" at the very least they will strengthen your perception of your dose. As in "Oh this line of really good coke has got me wanting to take a shit". Good coke does that. It's a good feeling. The shit's are glorious as I'm sure someone else here must know.
I've been an I.V drug user for 10 years, off and on of course.
I've I.V.'d just about 85% of the classes. but ill only contribute my novel experiences:
Tianeptine sodium: went on a 2-3 week binge / experiment used about 17 grams total, 90% or more was used I.V. At the time I had been taking kratom for around 18 months so the fact that I didn't take kratom those 3 weeks shows Tianeptine's ability to "hold" a person from withdrawl quite well. However, like tapentadol, which I've no experience with, Tianeptine is awfully hard on the veins. If one is going to do it get a hold of a 3 cc rig other wise you'll be doing 2-3 shots in rapid succession at like 65 mg's per 1 cc. This will give you a dilaudid like rush. I ended up forming a superficial blood clot because I already have vein damage and decided to just dedicate one vein to Tianept. for this "non polar" / not quite isotonic type solutions I've read you want the largest vein with the most rapid blood flow you can find. After you register you adjust your tourniquet so as to keep some reverse pressure in the needle, then as you push your shot your going to simultaneously gradually untie and release pressure. This is one where you DO NOT want to MISS ONE DROP outside the vein. Don't both with small veins unless its just 1 cc 50 mg shot. At the maximum load in 1 cc (100 mgs+ say) Ph will top out at 9-9.5. The blood clot I got was after considerable cumulative dosing in the same vein, and it was superficial meaning the E.R. didn't feel it necessary to prescribe anything and that it would dissipate on its own. He told me it's mainly larger deep vein clots that are big enough to cause pulmonary embolism (death). I don't think I collapsed any of my veins on this binge, maybe some small runs in my hand.
Dilaudid: Shot my fair share of the D's. To the point where they don't do what they used to to me. Something like 10X stronger when you I.V. it. not worth taking in any other ROA for people w/ opiod tolerance.
Dmt (n-,n) I don't think there is a "rush" with I.V. psychs. more just a rapid/instantaneous come up and peak. I get to the I.V. experience at the end. A good friend came over on valentines day and showed me some DMT he had been practicing extracting. It looked good enough to be a picture on erowid. light yellow crystalline structures. I took a 100 mg bong hit and broke through for my second time (I consider dmt special and only take it when it is offered by certain people, I do not seek it/ buy it) The last time I had done DMT was 5 years prior. After having a very controllable 30 minute DMT trip, half of it asking the universe to show me how to throw knives better (a hobby of mine). My friend left me a small amount, maybe 36 mg's or so (eyeballed but I'm def within 10 mgs). I read up on IV prep of organic base extracted dmt, what I had, and that it would only solute in water cleanly if the person who made it followed all proper procedures (and had practice a few runs too probably) to remove impurities / solvents. So long story short, the Dmt must have been above 95% pure or so because it took no heat or any heavy stirring for it to solute. I was not intending to trip again on DMT, and so as such I didn't even wait til I was fully down to baseline from the 100mg bong hit I took about 90-120 minutes prior. I believe DMT has some acute tolerance building where one needs to wait a few hours between "breaking through", that is why I took the dose when I did, not really wanting its full effects. So of course I did feel the DMT instantly, and it is definitely something I'll try again when I'm actually ready to trip. I plan to be laying in bed while I actually fire it, I've heard stories of people going through there whole DMT trip with the needle still stuck wherever. The only reason I can see someone doing this other than novelty is to maybe maximize their BOA of their substance therefor making it last longer. What I did was more so done so I could inform my friend that his labors bore good fruit.
Foot note: I.V. coke + heroin together (aka the speedball) is what absolutely destroyed me at a young age. Any of the inherently addictive substances; amphetamines and meth, cocaine, opiates, when I.V.'d take your addiction to a whole another level. Basically if you wanna use needles with those drugs you need to understand that you might lose your life, physically, mentally, or spiritually.
/ PSA
Edited like a zillion times cuz amps.