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57 Cards in this Set
- Front
- Back
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What are the 4 opioid receptor genes?
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mu, delta, kappa, ORL-1
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What does the mu opiod receptor do?
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responsible for anti-nociceptive (analgesia), tolerance and addictive properties (dependence) of opioids
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__ receptor may play a role in tolerance
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delta (and kappa)
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__ receptor may play a role in tolerance and dependence
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kappa
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What are the endogenous ligands that bind to opioid receptors?
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Proopioimelanocortin, Proenkephalin, Prodynorphin, Orphinan
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What is the signature peptide sequence in endogenous ligands?
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YGGF
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Which ligand has a high affinity for mu receptors; also binds to delta and kappa?
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Proopioimelanocortin
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What is the peptide sequence of Orphinan that makes it have high affinity for the ORL-1 receptor and no affinitity to the others?
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FGGF
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Which ligand is moderately selective for delta receptors?
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Proenkaphalin
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which ligand is moderately selective for kappa receptors?
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Prodymorphin
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What are the two enkaphlins?
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Met- and Leu-
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What receptor does Morphine bind to?
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mu
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What naturally occurring ligand binds to delta receptors?
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none
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What naturally occurring ligand binds to kappa receptors?
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Salvia
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What naturally occurring ligand binds to ORL-1 receptors?
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none known
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What is the most potent naturally occuring psychoactive substance?
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Salvia
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All opioid receptors are __ receptors
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G_alpha(i)
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What is the phenomenon of diminished receptor signalling that leads to tolerance?
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tachyphylaxis
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What are some tachyphylaxis mechanisms?
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receptor internalization
receptor densensitization arrestin-pathways involved |
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What are some mechanisms of craving and relapse caused by opioids?
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altered firing patterns of NE neurons
homeostatic changes in dynorphin gene expression permanent changes in neuronal firing |
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What is the basis of clonidine's actions on opioid withdrawl?
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altered firing patterns of NE neurons
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What is the basis of craving?
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homeostatic changes in dynorphin gene expression
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Where does acute morphine act in the brain (leading to diminished neuron firing)?
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locus coeruleus
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What happens with chronic morphine intake?
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desensitization of mu receptors which leads to normalized firing
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Abrupt withdrawl leads to increased firing of neurons. What can you give to abate this and why?
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alpha-2 agonist (clonodine). it normalizes firing
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morphine administration leads to __ dynorphin expression
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increased
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how does dynorphin contribute to craving after withdrawl?
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It inhibits dopamine release via the kappa receptors leading to craving and dysphoria after withdrawl
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T or F: a single dose of morphine leads to a long-lasting change in synaptic plasticity
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TRUE
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What receptor is analgesia mediated by?
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mu
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What are some effects of mu receptor activation?
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analgesia
euphoria sedation (except in kids --> excitement) respiratory depression cough suppression Miosis N/V Constipation |
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How do you tx opioid OD?
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IV naloxone (NARCAN)
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T or F: opioids cause physical and physchological dependence
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TRUE
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When do you avoid opioids?
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head injury pt
pregnancy impaired respiratory function (can be fatal) impaired renal/hepatic function (adjust dose) |
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What are some contraindications of opioids?
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sedative-hypnotics
antipsychotics MAO inhibitorss |
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T or F: Opioids decrease levels of serotonin and catecholamines
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False! They increase levels of serotonin and catecholamines
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When do you use morphine, hydromorphone, oxymorphone, and heroin?
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severe pain
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What is useful about codeine, oxycodone, dihydrocodone, hydrocodone compared to morphine?
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they are partial agonists w/ slightly less abuse potential
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What do you typically compound w/ acetaminophen leading to potential for toxicity?
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codeine and oxycodone, etc.
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__ is long-acting and approved for treating opioid withdrawl?
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Buprenorphine
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What is approved for treating opiod dependence with a relatively low abuse potential (but not zero)?
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methadone
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Which opioid has a low analgesic/low abuse potential?
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propoxyphene
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Which drugs induces a cross tolerance to morphine?
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methadone
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What are some of the most potent opioid analgesics?
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fentanyl, sifentamil, alfentanil, remifentanil
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Who are the most common fentanyl addicts?
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anasthesiologists
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Which opioid is a kappa agonist w/ mu partial agonists actions?
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butorphanol and pentazocine
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psychotic side effects are from what receptors?
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kappa
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abuse potential is from what receptor?
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mu
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What is a 5-HT reuptake inhibitor that may induce seizures whose metabolites are mu agonists?
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tramadol
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What is the main antitussive that is a sigma receptor agonists w/o much opioid receptor actions?
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dextromethorphan
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What suppresses severe cough?
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codeine
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T or F: dextromethorphan suppresses cough via opioid receptors
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false! it's from the sigma receptor
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What is a short acting opioid antagonist?
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naloxone
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What is a long-acting opioid antagonist that is used for alcohol addiction?
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naltrexone
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What is a SE of naltrexone?
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depression
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What do you give for constipation that is induced by opioids?
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methylnaltrexone (relistor)
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Why do pts on opioids get constipated?
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b/c the gut is full of mu receptors
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What is the analgesic effect of methylnaltrexone?
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none! it is peripherally active only
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