True statement regarding methadone are all except:
Ref: Goodman and Gilman 12th/506-507 Methadone *The onset of analgesia occurs 10-20 minutes after parenteral administration of methadone and 30-60 minutes after oral administration. *It is well absorbed from the GI tract and can be detected in plasma within 30 minutes of oral ingestion. *Primary uses are relief of chronic pain and in main tenance therapy of opioid addiction.