Opioids Flashcards
where do opioids come from
opium poppy seed pod juice
what 3 main drugs does opium contain
heroin, codeine, morphine
what is the difference between opiate and opioid
opiate = any natural component of opium
opioid = any natural or synthetic derivative of opium
why do we give opioids as pre-meds
because general anesthetics do not inhibit pain signal generation, so a painful stimulus during a procedure could transmit enough pain signals to the RAS to awaken the patient - giving an opioid prevents pain signal generation
where are opioid receptors present
pain pathways and in most other organ systems
T/F mammals produce endogenous opioids
T
what 5 uses are opioid drugs used for
1) analgesia
2) cough suppression (antitussive)
3) sedation
4) treatment of diarrhea
5) emesis (apomorphine)
what are the opioid receptor families that cause:
- immediate analgesia
- dysphoria
immediate analgesia:
- Mu
- Delta
- Kappa
dysphora:
- Sigma
what is the mechanism of action of opioids on pre-synaptic receptors
mu, delta, kappa receptors inhibit Ca entry, which inhibits NT release
what is the mechanism of action of opioids on post-synaptic receptors
mu receptors open K channels, which causes hyperpolarization and inhibits APs
what are the effects of mu opioid receptor stimulation (4)
- intense analgesia
- euphoria
- miosis or mydriasis
- respiratory depression (dose-dependent)
what are the effects of delta opioid receptor stimulation (4)
- analgesia
- respiratory depression, not as intense as mu
- protection from hypoxic injury
- hibernation
what are the effects of kappa opioid receptor stimulation
- moderate analgesia
- no respiratory depression
what are the effects of sigma opioid receptor stimulation
- dysphoria
- hallucinations
- respiratory and vasomotor stimulation
what can stimulate sigma receptors
opioids and some non-opioids such as ketamine
what are the 3 properties of opioid stimulation (i.e. what are the 3 ways that opioids can act on opioid receptors)
1) full agonist
2) partial agonist/antagonist
3) mixed agonist/antagonist
how does fentanyl act on opioid receptors (and which ones)
full mu agonist
how does butorphenol act on opioid receptors (and which ones)
mu partial agonist/antagonist and kappa agonist
T/F if you have a patient that presents with severe pain, you should first give a weaker opioid such as butorphanol and then give a stronger opioid such as fentanyl if pain persists
F; if you do this the butorphanol will block the effects of fentanyl by acting as a partial agonist/antagonist on the mu receptor
what two drugs are mu partial agonists/antagonists
butorphanol and buprenorphine
what is the difference between buprenorphine and butorphanol
both are mu partial agonists/antagonists, butorphanol is a kappa agonist whereas buprenorphine is a kappa antagonist
what are the 5 main analgesic opioids
1) morphine
2) hydromorphone
3) fentanyl
4) butorphanol
5) buprenorphine
what is the main anti-diarrheal opioid
loperamide
what is the main antitussive opioid
butorphanol
what is the main emetic opioid
apomorphine
what opioids are used for chemical immobilization
1) etorphine
2) carfentanyl
what is the duration of analgesia of hydromorphone
3-6h
what is the duration of analgesia of buprenorphine
4-8h
what is the analgesic potency of fentanyl relative to morphine
100x
are opioids weak acids or weak bases
bases
what is the metabolism of opioids
phase I and II metabolism with high first-pass effect
T/F codeine has a high analgesic effect in dogs because it gets metabolized to morphine
F
In regards to full mu agonists:
- sedation is most likely in _________
- excitement is likely in __________
- dogs and primates
- most other species
high doses of morphine cause what in cats; what drug does not do this
excitement - called sham rage;
not seen with hydromorphone
what can morphine trigger but not fentanyl or hydromorphone
histamine release -> hypotension
death from opioid overdose is due to
respiratory arrest -> due to respiratory depression (mu effect)
what do we use to reverse opioid overdose
naloxone
what effects to opioids have on the gastrointestinal tract
- increase segmentation but reduce propulsion -> constipation
- bile sphincter constriction -> biliary colic
- nausea and vomiting
what is the effect of opioids on the urogenital system
- increases bladder sphincter and detrusor muscle tone
- slows uterine contractions and inhibits birth reflexes
T/F fentanyl can be used as an analgesic + sedative prior to induction
T
overdose of fentanyl causes
seizures
how is fentanyl commonly administered
patch
etorphine is _______ more potent than morphine and carfentanyl is _____ more potent than morphine
4000x; 10,000x
what is the reversal agent for carfentanyl and etorphine (M99)
diprenorphine (M50/50)
the main beneficial effect of buprenorphine is via stimulation of what receptor
kappa receptor stimulation
T/F butorphanol is commonly used for post-op analgesia
T
how is buprenorphine administered in cats
IM; transmucosal at home
how is buprenorphine absorbed
transmucosally
what is the main advantage of buprenorphine
at home administration to animals with chronic pain
how is apomorphine given
in the eye
how does apomorphine trigger vomiting
dopamine receptors
T/F vomiting from apomorphine administration can be stopped by giving naloxone
F
how does naloxone work
inhibits mu receptors
T/F naloxone can be used to treat circulatory shock
T
