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54 Cards in this Set

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Opiod analgesic action
act on opiod receptors

SELECTIVE pain block - no change in consciousness or other sensations
Opium vs. opiates vs. opiods

Narcotics
Opium - dried resin from seed

Opiates - alkaloids found in some opium and synthetic derivatives

opiods - any agent with morphine-like activity

Narcotics
- any drug making you sleep (rarely used this way anymore)
- opiod analgesics
-legal term for abused substances
Endogenous opiods
made in body --> NTs/neuromodulators

mostly peptides, but also morpheine and codeine
families of endogenous opiods
enkephalins - preproenkephalin
endorphins - prepro-opiomelanocortin
endomorphins - don't know precursor
dynorphins - preprodynorphin
Opiod receptors
mu - most important
delta
kappa

most are full agonists, but there are also partial agonist, mixed agonist/antagonist (by receptor type), and antagonists
Preferred ligands for:

mu
Delta
Kappa
not totally specific

Mu: beta-endorphin, endomorphins
Delta: enkephalins
Kappa: dynorphins
Cellular effects of opiods
g-pro linked

opens K channel --> hyperpolarization

close some Ca channels --> down NT release

May alter adenylyl cyclase
receptors involved in some opiod fx

analgesia
down resp
down GI motility
psychotomimetic (LSD-like)
sedation
euphoria
miosis
increased sphincter tones
analgesia - mu (and some k)
down resp - mu
down GI motility - mu, k
psychotomimetic (LSD-like) - kappa
sedation - mu, k
euphoria - mu
miosis - mu, kappa
increased sphincter tones - mu
pharmacological effects of opiods
analgesia
euphoria/psychological dependence
sedation
resp depression
N&V
antitussive
miosis
pruitis
GI effects
blilary/ureter and bladder
CV effects
neuro endocrine
pharmacological effects of Opiod - anlgesia
affects both the psychological and emotional components
- raise pain threshold, decrease interpretation of remainign pain

selective block of pain

given enough opiods, you can block almost any pain (no ceiling effect) -- except neuropathic pain
Mech of analgesia for opiods
action in both brain and spinal cord

augment the effects of endogenous antinociceptive systems
Memorize that one diagram
yeah, that's right. Memorize it
pharmacological effects of Opiod - euphoria/psych depend
high abuse - only in people with abuse, not with medical use

mechanism - at least partly due to opiod activation of VTA/NA pleasure pathway
pharmacological effects of Opiod - sedation
drowsiness/impaired thinking

additive with EtOH
mainly at high doses
still don't cause loss of consciousness
no ataxia
usually can get analgesia w/o sedation
pharmacological effects of Opiod - respiratory depression
can be lethal, but can be useful

decreased rate and depth of breath

usual cause of death in OD

direct depression of brainstem resp centers (reduced responsiveness to CO2
Should I give passive O2 to someone with opiod OD?
NO!!! need to be pos pressure

if passive, the O2 will decrease the intrinsic drive to breathe even more
pharmacological effects of Opiod - N&V
partly due to chemorecepor trigger zone (CTZ)

better if person lays down (vestibular contribution)
pharmacological effects of Opiod - antitussive
depress cough reflex by action in 'cough center' of medulla

happens at low dose

receptors aren't well known
pharmacological effects of Opiod - miosis
pupil constriction - poor night vision

abuser don't like it b/c it points them out

don't get tolerance to it

stimulates Edinger-Westphal nuclues (increases parasympathetic tone)
pharmacological effects of Opiod - pruritis
ITCHING

more common with IJ than PO
histidine release from mast cells
can come with flushing/sweating
spinal mechanism?
pharmacological effects of Opiod - GI effects
down acid production
increased constipation from decreased intestinal, pancreatic secretions

partially due to local fx, partially CNS

Useful for diarrhea, often bad for SEs

Doesn't tolerate out
pharmacological effects of Opiod - biliary sphincter, ureter, bladder
increased tone in all

bilary stone/spasm = pain

enough opiod = mask pain, low dose = feel pain
pharmacological effects of Opiod - CV effects
not much CV effects

postural hypotension
pharmacological effects of Opiod - neuroendocrine effects
decreased gonadotropin-releasing hormone (GnRH)and corticotropin-releasing (CRH)hormone
--> erratic menstruation, decreased libio/impotence in men
Tolerance to opioids
inevitable with prolonged/frequent use

10x-100x is common

rate/magnitude varies by drug/dose/freq/duration

rate/magnitude also vary by effect (miosis/constipation don't tolerate out)

lots of cross-tolerance among MU agonists -> drug changing is common
Basis of tolerance to opioids
don't know exact mech

internalization of receptors

desensitization -- PO4 the receptor

uncouple receptor from g pro
Physical dependence to opiods
inevitable with prolonged/frequent use of MOST

morphine generally takes 10-14 days at tid/qid
-- differs per person per drug
opioid withdrawal
provoked with sudden decrease in dose or opioid receptor antagonist

symptoms - opioid craving, psych/physical effects (opposite of opioid effects)

unpleasant, but rarely lethal

onset/duration varies by agent half-life
opioid withdrawal symptoms
insomnia,
anxiety
irritability
dysphoria
sesitivity to pain
abdominal cramps
N&V
diarrhea
muscle aches
mydriasis
sweating
piloerection
tachycardia
hypertension
fever
Opioid detoxification
only prevents PHYSICAL dependence

1. switch to long acting opioid (methadone)
2. gradually change dose to wean off
3. eventually stop
Toxic OD of opioids
common cause of death in abuse

Triad of symptoms - resp depression, miosis (dilate with enough hypoxia) and coma

pulmonary edema = cause of death for 50% of cases
- initiated by mu receptors
- not reversible by antagonist

therapy is vital fcn support, opiod (MU) antagonist
- don't give too much
- very fast action (~5min)
Therapeutic effects of opioids
analgesia
cough supression
antidiarrheal
Adverse effects of opioids
Psych dependence
physical dependence
resp depression
N&V
dizziness
sedation
constipation
miosis
pruritis
biliary spasm
urinary retention
hypotension
Opioid kinetics (general rules)
well-absorbed
low F due to 1st pass

highly lipid soluble
- lots of routes available (nasal, buccal, skin, IM, SC, IV, intrathecal, epidural)
Morphine
full MU agonist

most common, inexpensive
terminal cancer use!
25% oral F, but ok due to low cost

morphine 6-glucuronide = active metabolite
- longer t1/2
- accumulates in chronic use
- lots of effects
Heroin
full MU agonist

no legit use in US

most widely abused opioid
more lipid soluble = more crosses BBB
active metabolite (monoacetyl morphine) which also crosses BBB
metabolised to morphine in brain
codeine (3 methyl-morphine)
low affinity MU agonist

10% metabolized by 2D6 to morphine (lots of polymorphisms = OD or no fx)

alone = not potent, but good when combined w/ NSAIDS

relatively high F

PSYCH dependence UNLIKELY but POSSIBLE
- common abuse = kids or people trying to avoid withdrawal to other opioid

PHYSICAl dependence extremely unlikely regardless of dose/duration
meperidine
DEMEROL, pethidine

1/10th as potent, shorter action

less constipation, miosis and urineary retention

toxic CNS stimulant is metabolite (normeperidine), long t1/2

Interact with MAOI - serotonin syndrome

mainly abused by HC pro's
Fentanyl
SUBLIMAZE

80-100x more potent
high lipid solubility
short duration (0.5-2h)

versatile
Fentanyl uses
pre-, intra-, post-op ANALGESIA

opioid ANESTHESIA
- not unconsicous, but not aware of pain

TRT chronic pain (patch) or breakthru pain (lollypop)

animal tranquilizer (esp w/ droperidol) dart gun
methadone
good F
long t1/2 (15-40h), strong tissue binding
methadone uses
analgesia

facilitate detox of opioid physical dependence

methadone maintenance:
no high, but occupies receptors
no withdrawal, craving
get person out of drug scene
makes person methadone-dependent, but they aren't an addict
diphenoxylate
LOMOTIL

exclusively for diarrhea
abuse unlikely --> added atropine = atropine poisoning b/f high
loperaminde
IMMODIUM

poor F

exclusively for diarrhea

abuse unlikely --> F ~0 therefore, action is only in gut
propoxyphene HCl
propoxyphene napsylate
DARVON/DARVON N

potency about same/less than codeine

for mild/moderate pain

PSYCH dependence, but not physical
Partial MU agonists and Mixed KAPPA agonist/ MU antagonist

Shared characteristics
big dose can cause withdrawal

minimal cross dependence

LOW:
-resp depression
-physical dependence

Low to Mod:
-psych dependence
buprenorphine
BUPRENEX
partial MU agonist
- bind tightly, slow dissociation = long duration

25-50x potency for analgesia

VERY low F --> only IJ or sublingual

Used as analgesic (vet med) and detox (subs for methadone)
pentazocine
TALWIN

strong KAPPA agonist, weak MU ANTagonist

analgesia from kappa agonism

Low F --> only slightly more potent than coediene (when PO)

psychotomimetic at large doses
TALWIN NX
petazocine + antihistimine = abuse as an IJ(similar to heroin)

add naloxone --> no effect when PO, but blocks effect when injected for abuse
butorphanol
STADOL
mixed kappa/mu antagonist
similar to pentazocine
Opioid antagonists shared charactersists
pure antagonist at ALL receptors

prevent/reverse all clinically active opioids

Used to treat OD and excessive Post-op effets
Examples of opioid antagonists
naloxone/NARCAN
naltrexone/REVIA
nalmefene/REVEX
tramdol
ULTRAM

weak MU agonist - similar to codeine/propoxyphene

inhibits 5HT/NE reuptake

moderate to severe pain

abuse potential low, but increasing
dextromethorphan
stereoisomer of opioid

NOT an opioid b/c no action at any known opioid receptor

No opioid or high/physical dependence

Increasingly abused for hallucinogenic effects
-Binds to PCP site