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.
It is a long acting u-receptor agonist
It is rapidly absorbed from the gastrointestinal tract and is detected in plasma 30 minutes after oral administration
The primary use of methadone is relief of chronic pain
The onset of analgesia is 30-60 minutes after parenteral administration and 1-2 hours after oral administration
Central Nervous system