Lecture 8 - Opioids Flashcards
Describe the analgesic pain ladder:
Step 1 - Mild
non-narcotics
1st choice = ASA
Alternatives = acetaminophen or NSAID
Describe the analgesic pain ladder:
Step 2 - Mild to Moderate
non-narcotics + weak narcotics
1st choice = ASA + codeien
Alternatives = codeine or Acetaminophen + codeine
Describe the analgesic pain ladder:
Step 3 - Moderate to Severe
moderate strength narcotics
1st choice = codeine or morphine
Alternatives = oxycodone, levorphanol, anileridine, oxymorphone
Describe the analgesic pain ladder:
Step 4 - Severe
strong narcotics
1st choice = morphine
Alternatives = methadone, hydromorphone
List 3 endogenous opioids
- endorphines
- enkaphalins
- dynorphins
Describe endorphins
- from pituitary and hypothalamus
- polypeptides
- from poropiomelanocortin and prodynorphin
- potent analgesics
Describe enkephalins
- from proenkephalin and prodynorphin
- pentapeptide ligands
- involved in modulated pain response
Describe dynorphins
- from proenkephalin B
- polypeptides
- physiological role not yet understood
Are opioids direct neurotransmitters?
No - they just make the neuron more likely to fire - but are not directly neurotransmitters
Describe the 3 Mechanisms of action?
1 - hyper polarization of nerves by opening K+/Ca2+ channels in 1st (receptor to medulla) and 2nd order neurons (medulla to thalamus)
2 - inhibition of ascending pathways in the CNS
3 - excitation of descending adrenergic and seratonergic pathways
What can opioids be used for?
- pain control
- sedation and anxiolysis
- can be used before anesthesia
What is the #1 cause of opioid death?
depression of respiration
List the 7 pharmacological effects of opioids
1 - inhibition of pain and pain perception
2 - sedation and anxiolysis
-drowsiness and lethargy
-cognitive impairment
-relaxation inhibition of pain
3 - depression of respiration (main cause of death from opioid overdose)
4 - cough suppression (opioids suppress the cough centre in the brain)
5 - reduction of intestinal motility (codeine used to treat diarrhea)
6 - pupillary constriction (KEY SYMPTOM OF OVERDOSE)
7 - nausea and vomiting (first stimulated, then inhibited)
_____ are used for pain, diarrhea, coughing, panic breathing (COPD)
opioids
What 3 things do we dose opioids by ?
by the mouth
by the clock
by the ladder
Briefly explain the WHO pain ladder (slide 8)
0-3: mild pain
- acetaminophen
- NSAIDs
- maybe caffeine
4-6: moderate pain
-codeine (mild opioid)
7-10: severe pain
-morphine (strong opioid)
If you are increasing to a stronger or different pain med, do you discontinue the original medication?
no
never
not in a million years
- *never stop the lower pain control!
- pain meds work by different mechanisms so you always want to keep the pain controlled and don’t want to take away any form of pain management
By the mouth:
-Oral dosing is ___ effective than IV
less
*because of first pass metabolism
Describe 3 points of by the mouth
1 - oral dosing has longer term effect requiring less frequent doses
2 - oral dosing avoids the highs and thus is less addictive
3 - oral dosing is safer in terms of overdose
Describe 3 points of by the clock
1 - uses less drug. It takes more drug to bring pain down than it does to maintain a person pain-free (maintain dosing)
2 - avoids the euphoria associated with release of pain, so less addictive potential
3 - avoids the development of chronic pain syndrome (from pain pathway rewirling)
What is the #1 problem with dosing by the clock?
Pt does not want to comply because they do not feel pain and do not want to become addicted
*have to explain to pt that by dosing by the clock, you are actually reducing risk of addiction
Describe points of by the ladder
1 - it assures that the safest and least potent drug required for any specific case is used
2 - avoids addictive potential because opioids (and strong opioids) are not used until required
_____ - weakest commonly used opioid and has the least addiction risk
codeine
codeine has ___% of potency of morphine
10