Triazolam is a benzodiazepine prescribed for insomnia. It disappears from the blood within 2-3 hours and some people find themselves in triazolam-withdrawal before morning.
Long-term use of OxyContin both legitimately and illicitly causes the body to adapt to the presence of the drug and withdrawal symptoms occur if use is reduced or stopped.
Short-term residential drug rehab was first designed to address alcohol problems, and then transitioned into a multi-faceted program during the cocaine epidemic in the mid-1980s, at which point many began to treat other types of addiction.
The fentanyl patch is a sustained release version which is supposed to be a 72 hour dose.