How Long Until Meth Is Out Of Your System? Methadone acts like an opioid in that it attaches to the same receptors in the brain, but it has a significantly longer half-life than other opioids.
The half-life of an opioid is the amount of time that it takes for half of the dose taken to have been processed out of the body. Most opioids have a half-life between 2 and 4 hours.
Methadone on the other hand has a half-life of about 15 to 20 hours.