Methadone has a half-life of up to 8 days in the human body. When subjected to the routine rapid detox procedure, the patients’ opiate receptors (mu receptors) in the brain, the spinal cord and the gastro-intestinal tract are quickly occupied by naloxone molecules, displacing the methadone molecules. The problem is that after the rapid detox process, the naloxone molecules themselves would leave the opiate receptors and be metabolized. Methadone molecules stored in the fatty tissue of the body are then free to re-occupy the opiate receptors, producing prolonged opiate withdrawal and craving for opiates.
There are two strategies to rapid detox methadone. One is to have the patients stop methadone 7 weeks before the detox, and switch to other shorter-lasting narcotics for that period. The other way is to immediately start the patients on Naltrexone oral treatment after intravenous rapid detox. The latter technique can produce worse residual withdrawal symptoms. The former, naturally, would require longer commitment from the patient, making two visits to the detox center, but entails much less hardship after detox.