Page 55 - phytochemistry II -pharmD general
P. 55
Narcotic antagonists
The structural change that convert a narcotic agonist to an antagonist, appears to
be the alkylation of the piperidine nitrogen i.e.
(replacement of the methyl group by propyl, allyl or isopropyl).
Ex. Nalorphine and Naloxone
Nalorphine Naloxone
are commonly used narcotic antagonist drugs which are competitive
antagonists that bind to the opioid receptors with higher affinity than agonists but
do not activate the receptors. This effectively blocks the receptor, preventing the
body from responding to opiates.
NMe
H
OMe O OMe
H
Thebaine Codeine
OpiuCm22Ha2l3kNaOl7oids 413.4
O
Me O MeO
N
O Me
NMe N
O MeO
MeO MeO H
C=O
H
COOH MeO
O
OMe MeO OMe
Narceine MeO O
OMe Noscpine Papaverine
54
