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14 Cards in this Set
- Front
- Back
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By what mechanism do opioids promote analgesia?
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Opioids bind to mu receptor in CNS.
Hyperpolarization of cells (increases outward K flux) Decreases cAMP, which decreases PKA, which decreases CREB. This leads to long-term changes. HOWEVER, IN CHRONIC USERS, THIS PATHWAY IS REVERSED...INCREASE IN cAMP b/c adenlyate cyclase chronically inhibited by opioid, INCREASE PKA, INCREASE CREB |
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By what mechanism do opioids promote euphoria?
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REWARD PATHWAY!
Mu opioid receptor binding to VTA/nuc.acc./PFC |
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What are side effects of opioid usage?
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Constipation, pupillary constriction, dilation of peripheral circulation, NAUSEA (in area postrema of brain), respiratory depression
DXM = anti-tussive. ROBITUSSIN (L and D-isomers) |
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Opioid withdrawal symptoms?
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Flu-like symptoms, pili erectae (hair standing up), pupillary dilation, dysphoria, anxiety, diarrhea
Related to PROTRACTED ABSTINENCE, opioid dependent individuals will undergo long-term PHYSIOLOGICAL changes. |
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Opioid neuroanatomy
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MU receptors mediate spinal (DRG) and supraspinal effects in periaqueductal grey, thalamus, sensory cortex.
Delta receptors meditate spinal analgesia for pain C fibers in spinothalamic tract. Located in dorsal horn of spinal cord. |
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What is the primary cause of death in opioid OD?
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Depression of neuronal sensitivity to pCO2 levels in brainstem.
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What are the three types of opioid receptors?
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Mu, kappa, delta.
All are GPCR |
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What are the three types of endogenous opioid ligands?
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Dynorphin (BINDS KAPPA)
Endorphin, Enkephalin (BINDS MU, DELTA) |
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What receptor binds preferentially to Dynorphin?
Endorphin? Enkephalin? |
Dynorphin = KAPPA
Enkephalin/Endorphin (the two E's) = MU, DELTA |
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What's the difference between naltrexone and naloxone?
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BOTH ARE MU OPIOID ANTAGONISTS
Naltrexone is longer lasting, used for alcohol dependence. Naloxone is shorter lasting, only used IV (combined with buprenorphine). |
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What happens to Mu receptors in tolerance?
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Downregulation of mu receptors...internalized, etc.
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What is methadone?
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Partial agonist/antagonist of mu opioid receptor. Blocks euphoric and analgesic effect. Users won't feel effect of heroin.
Increased rates of productivity while decreasing deliquency/STDs |
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What is buprenorphine-naloxone for heroin addiction?
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Buprenorphine is an orally-active partial opioid agonist with slow dissociation from opioid receptor. Few withdrawal symptoms. Combination cannot be injected bc naloxone (only active IV) would cause IMMEDIATE ACUTE WITHDRAWAL SYMPTOMS
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What is the difference between benzos and naltrexone in treating alcohol dependence?
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Benzos are used for withdrawal (DT) symptoms.
Naltrexone is used for preventing/limiting further abuse. Naltrexone not effective for ABSTINENCE, but DOES REDUCE EUPHORIA AND REDUCES HEAVY DRINKING RELAPSE. |
