Opioids Flashcards
what are the four steps in feeling pain?
transduction
transmission
modulation
perception
what two places in four steps of feeling pain do opioids work?
modulation and transmission
where doe descending and ascneding pain sensations summate in the SC?
dorsal horn…good spot for opioid action
where else are mu opioid receptors found in body other than brain and SC?
peripheral nociceptor neurons and GI
name the full agonists opioids
codeine morphine hydrocodone oxycodone heroin methadone meperidine fentanyl remifentanil carfentanil
what is most potent full agonist?
carfentanil
what opioid is used to compare potency?
morphine set as 1
what are oral opiods subject to?
first pass effect
where are opioids mainly cleared
kidneys
what are opiods broken down into before clearance?
polar metabolites
what three drugs are broken down into more potent drugs?
codeine
hydrocodone
oxycodone
what is secondary effect of increased morphine metabolites in system?
seizures
what is codeine broken down into?
morphine
what is hydrocodone broken down into?
hydromorphone
what is oxycodone broken down into?
oxymorphone
what is secondary effect of increased hydromorhpone metabolites in system?
neurotoxicity
name the foursafe opioids to give with renal failure
fentanyl
hydromorhpone
methadone
buprenorphine
what do opioids do to pre synaptic neuron in ascending path?
inhibit voltage gates Ca2+ entry
what do opioids do to post synaptic neuron in ascending path?
increase K+ efflux…hyperpolarize cell
what is opioids MoA in descending path?
inhibits GABA so GABA cannot inhibit the pathway anymore
how do opioids inhibit GABA in descending path?
inhib Ca2+ influx in presynaptic terminal to release GABA…so decreases GABA release
what are three adverse affects with acut opioid use?
respiratory depression
constipation
sedation
what are three adverse opioid effects with chronic use?
hyperalgesia
tolerance
withdrawal
where are there mu opioid receptors that contribute to respiratory depression?
respiratory center of the pons
how do opioids cause constipation?
target mu opioid receptors in GI and lead to less contraction of SM there
what opiods is used to treat diarrhea?
fentanyl and eluxadoline
what drug class treats opioid induced constipation?
PAMORAs
what are PAMORAS
peripherally acting mu opiod receptor antagonsits
what is the PAMORA to know?
methylnaltrexone
if patient builds up tolerance to opioid what can you do? but what can be issue with this?
can switch to other opioid…but often has cross tolerance
how do opioids lead to euphoria/addiction?
stimulate the mesolimbic dopaminergic pathway by inhibiting GABA release so dopamine is uninhibited
when is peak opioid withdrawal?
72 hours after last dose
what are symptoms of opioid withdrawal?
chills, fever, body ache, msucle pain, nausea, dilated pupils
what type of opioid is methadone?
full agonist
what is unique about methadone in treating opioid addiction?
has very long halflife and can satisfy cravings…and does not lead to withdrawal symptoms
what class of opioids is buprenorphine?
partial agonist
how does buprenorphine treat addiction?
partially substitutes full agonist opiods…so reduces withdrawal symptoms and eases detox
what two meds are used in acute overdose? why?
naloxone and naltrexone …because they are antagonist and inverse agonist
what does it mean for naloxone/naltrexone to be inverse agonist?
take away the basal level of firing of the mu opioid receptor
what does it mean for naloxone/naltrexone to be antagonist?
inhibit binding of other opioids to mu receptor
what is suboxone?
combo of buprenorphine and naloxone
