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36 Cards in this Set
- Front
- Back
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What is an opioid?
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Any chemical compound with pharmacologic actions similar to those of morphine
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What are the 2 naturally occurring opioids?
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1. Morphine
2. Codeine |
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What is an orally active opioid antagonist?
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Naltrexone
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What is a parenterally active opioid antagonist?
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Naloxone
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What are the 2 types of pain that are alleviated by opioids?
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Somatic Pain - sharp, intense pain
Visceral Pain - diffuse, poorly localized |
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A person under the influence of an opioid analgesic might say what in response to pain?
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"It hurts but who cares"
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What is the CNS action of opioids?
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1. Analgesia
2. Euphoria (dysphoria) |
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What is the Cardiovascular effect of opioids?
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Peripheral vasodilation
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What effects in the eyes are seen with opioids?
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Pupillary constriction
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What respiratory effects are seen with opioids?
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Respiratory depression
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What GI effects are seen with opioids?
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Decrease in the propulsive contractions in the small intestine and colon (constipation)
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Why are oral doses of morphine much larger the IV?
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Due to first pass metabolism in the liver
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Opioids activate what to decrease pain perception at the supraspinal level?
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Periacqueductal grey (PAG) matter
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Opioid euphoria is produced by which neurons and where do they project?
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VTA dopaminergic neurons which project to the n. accumbens and medial prefrontal cortex
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What is the cause of death in opioid OD?
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Respiratory Depression
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Opioid agonists bind to what receptors on what type of interneurons?
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Mu receptors on GABA interneurons
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What is the MOA of opioids?
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Inhibit activity of GABA interneurons which normally inhibit the VTA dopaminergic neurons
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What are the 3 main opioid receptor subtypes?
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1. Mu
2. Delta 3. Kappa |
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Which opioid receptor subtype mediates some of the aversive (dysphoric) effects of opioids?
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Kappa
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What are the 3 main endogenous opioid receptor ligands in the CNS?
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1. Endorphin
2. Enkephalin 3. Dynorphin |
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How does the affinity of naltrexone and naloxone antagonists compare to agonists (ex: morphine)?
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Antagonists have a greater affinity
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What are 3 acute cellular responses of GABA interneurons to morphine?
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1. Decrease in Firing
2. Adenylyl cyclase inhibited 3. Hyperpolarization via opening of K+ channels |
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What is naloxone used for?
How is it administered? Onset/Half life? |
- Used for reversal of mu opioid agonist OD.
- Administered IV - Very rapid onset, lasts several hours |
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What is naltrexone used for?
How is it administered? Onset? |
Used for alcohol addiction
Oral acting Longer lasting (48 hours) |
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What is the cellular mechanism of opioid tolerance?
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Mu receptor phosphorylation
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Ultimately, what is increased in the chronic response to morphine?
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cAMP
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What molecule mediates Mu receptor internalization?
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Beta-arrestin 2 binding to phosphorylated Mu receptor
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What 2 neuronal remodeling mechanisms might account for opioid tolerance?
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1. Widespread loss of dendritic arborization
2. Inhibition of neurogenesis in hippocampus |
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What are the physical symptoms of the opioid withdrawal?
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Mild and the OPPOSITE of those produced by morphine
Anxiety, agitation, diarrhea, pupil dilation |
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What is the main treatment for opioid addiction?
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Methadone treatment
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What drug combination is a promising new treatment for opioid addiction?
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Buprenorphine-naloxone
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Why is naloxone placed in the combination?
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Because if crushed up and injected, actually injection an antagonist
Naloxone is inactivated if taken orally (as it's supposed to be) |
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G allele carriers are what in response to Mu receptor agonists?
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HYPO-responsive to Mu opioid receptor agonists
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G allele carries are what in response to Mu receptor antagonists?
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HYPER-responseive
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How do G allele carriers experience alcohol?
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With greater euphoria
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Did alcoholic G allele carriers show a more efficacious response to naltrexone?
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Yes (85%)
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