Opiods Flashcards
1
Q
What are considered endogenous opioids?
A
- Endorphins: from pituitary and hypothalamus, polypeptides, porporiomelanocortin and prodynorphin, potent analgesics
- Enkephalins: from proenkephalin and prodynorphin, pentapeptide ligands, and is involved in modulating the pain response
- Dynorphins: from prenkephalin B, polypeptides, physiological role is not yet understood
2
Q
MOA of opioids
A
- hyper polarization of nerves by opening K channels/ calcium channels in 1st (receptor to medulla) and 2nd order neurons (medulla to thalamus)
- inhibition of ascending pathway in the CNS
- excitation of descending adrenergic and seratonerigic pathways
3
Q
Where do opioids come from?
A
opium poppy
- has the active ingredients of morphine and codeine
4
Q
What is the pharmacological effects of opioids?
A
- inhibition of pain and pain perception
- sedation and anxiolysis
(drowsiness and lethargy, cognitive impairment, relaxation and inhibition of pain) - depression of respiration (can be clinically useful in those that are at the end of their lives)
- cough suppression
- reduction of intestinal motility - codeine can be used to treat diarrhea
- pupillary constriction
- nausea and vomiting -
5
Q
Opioids are used for what?
A
pain, diarrhea, coughing, and panic breathing in COPD
6
Q
What does it mean to dose opioids by the mouth, by the clock and by the ladder?
A
- want to ALWAYS give someone acetaminophen first to handle their pain
- then you can set up to codeine as a second step- it is a very mild opioid
- all the way through, you want to keep the patients on acetaminophen!
- if codeine does not work, then you can dose morphine- this is also taken at the same time as acetaminophen
7
Q
What does “by the mouth” mean?
A
- oral dosing is less effective than IV, BUT..
oral dosing as longer term effect (less frequent doses), it avoids the highs and thus is less addictive, and oral dosing is safer in terms of an overdose
8
Q
What does “by the clock” mean?
A
- uses less drug - it takes more drug to bring pain down than it does to maintain a person pain-free
- avoids the euphoria associated with release of pain, so less addictive potential
- avoids the development of chronic pain syndromes (from pain pathway rewiring)
- want to dose the person on their opioid every set amount of hours RELIGIOUSLY- it takes less drug to keep the pain away than it does to drop the pain once it comes back
- there is the danger when the person is going in and out of pain that it will remodel their spinal column- can cause chronic pain
- want to dose by the clock, not by the pain
9
Q
What does dosing “by the ladder” mean?
A
- assures that the safest and least potent drug is required for ay specific case
- avoids addictive potential because opioids and strong opioids are not used until required
10
Q
Describe codeine
A
- weakest commonly used opioid - very little addiction risk
- potency is so low that it has its own step on the ladder (tramadol here too)
- used for pain, diarrhea, coughing and to inhibit breathing
11
Q
Describe Tramadol
A
- is considered a unique opioid agonist
- has a similar structure to codeine and morphine, so it is in the opiate agonist class
- unlike other opioids, it has 2 complementary mechanisms
1. like other opioids, activates the u- opioid receptor
2. weak inhibitor of NE and serotonin retake - there is less potential for addiction, and shows greater pain control than can be explained by weak opioid action
- with acetaminophen, this drug is known as tramacet
12
Q
Describe morphine
A
- oral has a relatively poor bioavailability due to first pass metabolism
- latency to onset - 15-60 minutes
- has a duration of action of 3 to 6 hours
- IV is twice and potent as oral forms
- duration of action - almost immediate to around 2 hours (there is a high population variability here)
13
Q
Describe oxycodone
A
- has equal or slightly greater potency than morphine (up to 2x)
- has oral bioavailability of 80%
- half life is slightly greater than morphine- dosed at half morphine dose for equivalent effects
- slow release is OxyContin
- with Tylenol it is known as percocet
14
Q
Describe hydromorphone
A
- oral: latency to onset is 15-30 minutes
- IV: DOA is 3-4 hours
- peak effect: 30-60 minutes
- is 5x as potent as morphine for pain
- used in surgical settings for moderate to severe pain (cancer, etc)
- not more effective than morphine, but it is more potent
15
Q
Describe fentanyl
A
- highly lipophilic and very potent (thin patient/patch)
- 8x the analgesic potency of morphine and 10x the analgesic potency of hydrophorphone
- sublingual and transdermal- rarely IV
- Sublingual - latency is 7012 minutes with a duration of 1-2 hour. Used for acute, temporary pain
- Transdermal - latency 12-17 hours - duration of 72-96 hours. Used in more severe pain(cancer)
16
Q
Describe naltrexone
A
- this is an oral opioid inhibitor!
- latency: 15-30 minutes
- reverse the psychotomimetic effects of opiate agonists, reverses hypotension and cardiovascular instability
- it is NOT highly effective in treating opioid addiction, but IS effective to some extent in treating alcohol addiction
- can actually kill someone if you give them this when they;re addicted to opioids because it knocks all the opioids off of the receptor
- very effective because it gets rid of the positive effects of alcohol- before you start drinking you take the naltrexone, and drinking is not pleasurable anymore
17
Q
Describe naloxone
A
- a potent opioid antagonist
- quickly blocks opioid binding
- used in emergency situations, like respiratory depression in heroin overdose. Has a short half life
- blocks all major effects of opioids including pain control
18
Q
How is naloxone so unique in the ways that it is effective?
A
- naloxone is only effective when it is ground up and injected - the naloxone will blocks the receptors and make the opioids not effective, but ONLY IF IT IS GROUND
- if the drug is taken orally like its supposed to - THIS DOES NOT HAPPEN
19
Q
Describe methadone
A
Methadone has a very long but variable half life, but is effective for only 6-12 hours
- at least 10x more potent than morphine, but variable
- less addictive but has a greater risk for accidental overdose (even in a medical setting)
- requires special training and licence
- used mostly for addiction meds and in palliative care when resistance has been developed to other opioids
20
Q
What is the important thing to remember when prescribing opioids?
A
- want to titrate up the dose of opioid based on response and side effects until the maximum analgesia and function are attained with tolerable side effects
- if possible, want to switch to long acting opioids at equianalgesic doses
- long acting opioids reduce the likelihood that the patient will “watch the clock” and reduces peaks and valleys in pain control
21
Q
When should therapy be discontinued?
A
- when there are intolerable or unacceptable side effects with little or no evidence of analgesia
- high doses of opioids without analgesia
- there is evidence of addiction
- there is no evidence of any effort to increase function in the face of reasonable analgesia
22
Q
What is opioid tolerance?
A
- reduced potency of analgesic effects of opioids following repeated administration - i.e.. increasing doses are necessary to produce pain relief
- related to opioid receptor regulation
- less common in patients with cancer pain
- often reason patients save opioids until the terminal phase
23
Q
What is opioid dependence?
A
physical dependence: the normal response to chronic opioid administration
- evident with opioid withdrawal- yawning, sweating, tremor, fever, increased heart rate, insomnia, muscle/ abdominal cramps, dilated pupils
- avoided by decreasing the dose to 20-30% per day
24
Q
What is opioid addiction?
A
- psychological dependence
- drug use characterized by a craving for opioids that is manifested by compulsive drug seeing behaviour leading to overwhelming involvement, use and procurement of drugs
