True statement regarding methadone are all EXCEPT
Essentials of medical pharmacology, seventh edition, page no 476 Answer is option 4, onset of analgesia is 30-40min after parenteral administration and 1-2 hours after oral administration. Methadone is a long acting u-receptor. It is rapidly absorbed from gastrointestinal tract. Here all statements are true except 4. Ref ; KATZUNG 13TH ED.