In 2011/2012, I used to take >=1200 milligrams of Oxycodone (in the form of OxyContin and OxyNorm) a day, on top of a lot of alcohol and a shitload of benzodiazepines. I never, not even once, overdosed. Of course, my tolerance was built up gradually, over the course of more than a year, maybe even two years. My doctor would prescribe me anything (he doesn't anymore, unfortunately).
When I went into rehab, they only gave me Tranxène (and not even that much). Not even a microgram of Suboxone. I lost 20 kilograms (over 40 pounds) in 10 days and almost didn't sleep for 11 days. I sufffered multiple seizures, but the hospital doctors wouldn't give me anything for some relief. I went through cold turkey withdrawal after that multiple times, mostly from Heroin, but never did I suffer like I did when I was in rehab for those massive doses of Oxy, alcohol and benzodiazepines. When I was out of rehab and told this to my psychiatrist, she got REALLY angry (she is a rather known and influential doctor with a very good knowledge of drug withdrawal, she even is a doctor in a rehab clinic , another one of course, as well) and said she was going to confront the doctors that "treated" me.
Anyway, that withdrawal sucked ass!!!!!