pharmacology of Narcotics Analgesics

Some narcotic analgesics combine an opioid with aspirin, acetaminophen, or ibuprofen. Examples include: Percodan (chemical name: oxycodone and aspirin), Percocet and Roxicet (chemical name: oxycodone and acetaminophen), Vicodin, Lorcet, and Lortab (chemical name: hydrocodone and acetaminophen).

1. NarcoticsAnalgesics
MohdAsadFarooqi

2. Analgesics
Ananalgesic,orpainkiller,isanymemberofthegroup
of drugs used to achieve analgesia —relief frompain.
Major classes of Analgesic Drugsinclude:
➢Opioids
➢NSAIDs
➢Acetaminophen/PCM
➢Flupirtine
➢Ziconotide

3. NarcoticsAnalgesic/Opioids
Narcoticanalgesicsaredrugsthatrelievepain,
bybindingtoopioidreceptors,whichare
presentinthecentralandperipheralnervous
system,cancausenumbnessandinduceastate
ofunconsciousness.

4. Classifiedinto:
NaturalCompounds:Morphine, Codeine,Papaverine
Semi-Synthetic:Diacetylmorphine(Heroin),benzylmorphine
and ethylmorphine
SyntheticDerivatives:Fentanyl,Pethidine,Methadone,
Tramadol and Propoxyphene
Loperamide,anopiatethatdoesnotenterthebrainand
therefore lacks analgesicactivity.

5. MechanismofAction
AllopioidreceptorsareG-protein
coupledreceptorsandinhibit
adenylatecyclase.
They are also involvedin
➢Postsynaptichyperpolarization
(increasing K+efflux)
➢Reducing presynaptic Ca
++
influx
thus inhibits neuronalactivity.

6. OpioidReceptors
AllopioidreceptorsarelinkedthroughG-proteinsto
inhibitionofadenylatecyclase.Theyalsofacilitate
hyperpolarisation)andinhibit
openingofpotassiumchannels
openingof
(causing
calcium
channels (inhibiting transmitterrelease).
They are of 4types:
➢μreceptor
➢σreceptor
➢δreceptor
➢Κ receptor

7. μ-Receptorsarethoughttoberesponsibleformostofthe
analgesiceffectsofopioids,andforsomemajorunwanted
effects.Mostoftheanalgesicopioidsareμ-receptor
agonists.

8. ➢κ-Receptorscontributetoanalgesiaatthespinalleveland
mayelicitsedationanddysphoria,butproducerelatively
fewunwantedeffectsanddonotcontributeto
dependence.
➢δ-Receptorsareprobablymoreimportantintheperiphery
andmayalsocontributetoanalgesia.
➢σ-Receptorsarenottrueopioidreceptorsanditisunclear
thatwhatdeltaactuallyresponsibleforbutmayregulate
mureceptoractivity.

9. Morphine
Morphineisthemajoranalgesicdrugcontainedincrude
opiumandistheprototypestrongagonist.
Morphinemaybegivenbyinjection(intravenousor
intramuscular)orbymouth,oftenasslow-releasetablets.
Itismetabolizedtomorphine-6-glucuronide,whichis
morepotentasananalgesic.
Actions ofMorphine:
➢Analgesia
➢Euphoria andsedation
➢Respiratory depression and suppression ofcough
➢Nausea and vomiting
➢Reduced gastrointestinal motility, causingconstipation
➢Histamine release, causingbronchoconstriction.

10. Disadvantage:
➢Drug of addiction due to euphoriceffect
➢Over dose causes poisoning i.e. Coma andRespiratory
Depression.
➢Cause dryness of mouth, mental clouding,vomiting,
headache, fatigue, constipationetc.