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Pharmacology
Opiod Analgesics
71
Medical
Graduate
10/09/2009

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Term
What are the endogenous opiods of our nervous system?
Definition
endorphins, dynorphins (A and B), and leu-enkephalin
Term
What protein gives rise to endorphins?
Definition
POMC via ACTH
Term
What protein gives rise to leu-enkephalin?
Definition
proenkephalin
Term
What protein gives rise to dynorphins?
Definition
prodynorphin
Term
Activation of what receptor is responsible for the therapeutic and side effects of morphine?
Definition
mu
Term
What two nerve membrane channels does morphine affect? What second mesenger signaling molecule?
Definition
potassium (increased opening) and calcium (reduced opening) -> decreased nerve transmission; Adenylate cyclase is inhibited
Term
Which receptors mediate the psychotomimetic effects of opiate analgesics? do endogenous opiods activate them as well?
Definition
sigma and phencyclidine receptors; no
Term
Which receptors are responsible for the antitussive effect of codeine
Definition
regular opiod receptors
Term
How are codeine and heroin related to morphine?
Definition
they are prodrugs that are converted into morphine
Term
what is allodynia and what cuases it?
Definition
pain caused by previously innocuous stimuli due both to perihperal sensitization and to longer term changes in spinal mechanisms
Term
What are the sites for opiate analgesia?
Definition
primary afferents (peripheral nociceptors); opiod interneurons in dorsal horn of spinal cord (they gate nociceptive inputs)
Term
Thinking about the sites where morphine and opiod analgesics are active, what are the implications in terms of how you'd administer opiates?
Definition
intrathecally or epidural routes
Term
How come TCAs and SSRIs are able to potentiate opiate analgesia?
Definition
there are descending pathways from pons that potentiate spinal analgesia that use serotonin and noradrenaline as NTs
Term
What role do PGE2 and PGI2 play in the role of pain?
Definition
they sensitive the peripheral nerve endings
Term
How does morphine affect:
consciousness;
Other sensory modalities;
dull & shrap intermittent pain;
affective (suffering) component of pain
Definition
Occurs w.out loss of consciousness;
other sesnory modalities less altered;
continusous dull > sharp intermittent;
alleivates snesory and affective component
Term
What are morphines physiologic actions?
Definition
Morphine gives you one "HECC of a DREAM" Hisamine and Hormonal actions; Emesis; Contraction of biliary smooth muscle (biliary colic) and Cardiovascular changes (hypotension); Decreased cough reflex, Decreased GI motility, Depression of mental functioning; Respiratory depression; Eurphoria; Analagesia; Miosis
Term
Why is it dangerous to administer oxygen to a person under morphine administration?
Definition
Morphine depresses the brain-stem respiratory generator, so respiration becomes soley dependent on the carotid chemoreceptors which are stimulated by HYPOXIA and a higher than normal PCO2 to keep respiration going.
Term
What are pin point pupils a sign of?
Definition
possible morphine toxciity (due to central effect on EW nucleus of oculomotor nerve)
Term
How would you treat hypoxia in an overdose morphinated patient?
Definition
ventilation only (administering oxygen will decrease respiratory drive)
Term
Name an opiod receptor antagonist
Definition
naloxone
Term
Naloxone is what kind of drug?
Definition
opiate receptor antagonist
Term
What can naloxone be used for?
Definition
treatment of morphine overdose
Term
T1/2 morphine
Definition
4 hrs
Term
Administration
Definition
oral, subcutaenous, IM, IV
Term
How well does morphine penetrate the CNS? What is it about its structure that determines its ability to penetrate?
Definition
poorly in comparison to other opiod analgesics; it's highly hydroxylated
Term
Metabolism and Excretion: morphine
Definition
conjugated with glucoronic acid in the liver and excreted via urinary and 10% biliary
Term
What type of tolerance is seen in morphine?
Definition
pharmacodyanmic
Term
physical dependence: morphine
Definition
prominent
Term
codeine is what kind of drug?
Definition
opiod agonst like morphine
Term
hydromorphone is what kind of drug?
Definition
opiod agonist
Term
oxymorphone is what kind of drug?
Definition
opiod agonist
Term
oxycodone is what kind of drug?
Definition
opiod agonist
Term
hydrocodone is what kind of drug?
Definition
opiod agonist
Term
heroin is what kind of drug?
Definition
opiod agonist
Term
levorphanol is what kind of drug?
Definition
opiod agonist
Term
meperidine is what kind of drug?
Definition
phenylpiperidine drivative opiate
Term
Preferred opiate for obstetrical analgesia?
Definition
meperidine as it produces less respiratory depression in the newborn
Term
What side fx does meperidine lack compared to morphine?
Definition
less spasmogenic, less constipation and urine retention, doesn't inhibit coug
Term
Which opiates are virtually insoluble in waterand so can't be administered IV or parenterally?
Definition
diphenoxylate
Term
diphenoxylate is what kind of drug?
Definition
an opiate that at low doses tx diarrhea and at higher doses show typical opiod activity
Term
fentanyl and sufentanyl are what kinds of drugs?
Definition
opiods
Term
which opiates are 80x more potent than morphine
Definition
fentanyl and sufetanyl
Term
T1/2 Methadone
Definition
long - 15 hrs (compare with morphines 4 hrs)
Term
what kind of drug is methadone?
Definition
opiate agonist that has identical pharmacology as morphine
Term
How is methadone superior to morphine?
Definition
oral absorption, larger T 1/2, lesser withdrawal sx
Term
propoxyphene is what kind of drug?
Definition
opiate agonist
Term
compare effectiveness of propoxyphene and codeine as well as abuse libaility
Definition
codeine is more effective but greater abuse potential
Term
1- acetylmethadol is what kind of drug?
Definition
opiod that produces methadone
Term
What is so special about 1-acetylmethadol?
Definition
because it can be given as a depot and is structurally modified version of methadone, it is very long lasting and only needs to be admin. ever 2 or 3 days
Term
Pentazocin is what kind of drug?
Definition
mixed action opiod
Term
Mechanism of action: pentazocin
Definition
weak antagonist a mu receptors, powerful kappa agonist
Term
What are particular side effects of pentazocin?
Definition
at doses requried to tx intense pain: anxiety, disturbing thoughts, nightmares, hallucinations
Term
T or F: pentazocin can produce analgesia and morphinmimetic fx?
Definition
when administered alone, yes
Term
T or F: pentazocin reduces morphine analgesia (but not its respiratory depression)
Definition
true. it can precipitate withdrawal sx in morphine tolerant individuals
Term
buprenorphine is what kind of drug?
Definition
mixed action opiod
Term
naloxone is what kind of drug?
Definition
opiod antagonist
Term
naltrexone is what kind of drug?
Definition
opiod antagonist
Term
Route of administration: naloxone
Definition
only iv (zero oral bioavailability)
Term
T 1/2: naloxone
Definition
short (i.v. admin)
Term
route of admin: naltrexone
Definition
oral
Term
T 1/2: naltrexone
Definition
longer than naloxone (b/c oral administered)
Term
dextromethorphan is what kind of drug?
Definition
antitussive; optical isomer of levorphanol is dextrorphan - this drug is the methoxylated for of dextrorphan
Term
t or f. dextromethorphan has zero analgesic potentcy, zero affinity for opiod receptor, and minimal toxicity?
Definition
true
Term
What are the 3 main criteria in guiding selection of opiod analgesic?
Definition
type of pain, required duration of action, intensity of pain
Term
Opiods not only act on the CNS but on the...
Definition
gut! it is sensitive to doses of opiates FAR below those requried to produce analgesia
Term
which opiate can be used a low dose to tx diarrhea?
Definition
diphenoxylate
Term
What are 4 ways to tx opiate abuse?
Definition
replacement therapy with agonists (methaone, acetyl-methadol); antagonist (naltrexone - longer duration of action); partial agonists (buprenex); clonidine
Term
How does this drug tx opiate abuse: clonidine
Definition
this is an alpha 2 agonist so it reduces some of the withdrawal effects of opiates by attenuating intesnity of autonomic components and by producing sedation
Term
How does this drug tx opiate abuse: methadone; acetyl-methadol
Definition
breaks habit of injecting drugs, no withdrawal fear, no buying of illegal drugs, long T1/2 (so less serious withdrawal)
Term
How does this drug tx opiate abuse: naltrexone
Definition
long last antagonist which can be good during early detoxification phase
Term
How does this drug tx opiate abuse: buprenorphine
Definition
a u-receptor partial agonist antagonizes high potency agonists but keeps opiate receptors somewhat stimulated
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