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50 Cards in this Set
- Front
- Back
Define opiods
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all exogenous substances, natural and synthetic, that bind specifically to opiod receptors and produce some agonist (morphine like) effects
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What is potency of opiods related to?
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The stereochemical structure of the molecule.
*Levo-isomers are most active |
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List and describe the three types of opiods
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1) Naturally occuring= Levoisomer or L-Morphine
2) Semisynthetic= result from minor modification of morphine molecule 3) Synthetic= contain phenanthrene nucleus of morphine but are manufactured by synthesis rather than chemical modification of morphine. |
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What are the principal pharmacodynamic differences between opiod drugs?
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1) potency
2) rate of equilibration between plasma and site of drug effect |
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Where are the opiod receptors located in the body?
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1) Stereospecific Opiod Receptors in the CNS
2) Outside the CNS in peripheral tissues. |
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What is the mode of action of Opiods?
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Opiods mimic the actions of endogenous peptide opiod receptor ligands (endorphins) by binding to opiod receptors
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What does binding of opiods to their receptors result in?
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Activation of Pain-modulating (antinocieptive) systems.
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What are the effects of opiod receptor activation?
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1) Primary effect is decrease in neurotransmission (results from presynaptic inhibition of neurotransmitter release such as AcH, dopa, norepi, substance p)
2) Increased potassium conductance, leading to hyperpolarization of cellular membranes. |
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What does depression of cholinergic transmission in the CNS result in?
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Opiod induced inhibition of acetylcholine release from nerve endings, producing significant analgesic and otherh side effects (depression of ventilation)
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What are the four classifications of Opiod receptors?
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Mu1, Mu 2, Delta, Kappa
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What are the four classifications of Opiod receptors?
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Mu1, Mu 2, Delta, Kappa
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List the Effects, associated with Mu1 receptors.
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Effects: Analgesia (supraspinal, spinal), Euphoria, Low abuse potential, Miosis, Bradycardia, Hypothermia, Urinary retention.
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List the agonists associated with Mu1 receptors.
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Endorphins, Morphine, Synthetic Opiods.
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List the Antagonists associated with Mu1 Receptors.
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Naloxone, Naltrexone, Nalmefene.
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List the Effects associated with Mu2 receptors.
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Analgesia (spinal), Depression of ventilation, physical dependence, constipation (marked)
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List the Agonists associated with Mu2 receptors.
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Endorphins, Morphine, Synthetic opiods.
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List the Antagonists associated with Mu2 receptors
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Naloxone, Naltrexone, Nalmefene
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List the effects associated with Kappa opiod receptors.
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Analgesia (supraspinal, spinal), Dysphoria, sedation, low abuse potential, diuresis.
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List the agonist associated with Kappa opiod receptors
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Dynorphins
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List the antagonist associated with Kappa opiod receptors
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Naloxone, Naltrexone, Nalmefene
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List the effects associated with Delta opiod receptors
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Analgesia (supraspinal, spinal), Depression of ventilation, physical dependence, constipation, urinary retention.
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List the agonists associated with Delta opiod receptors
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Enkephalins
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List the antagonists associated with Delta opiod receptors
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Naloxone, Naltrexone, Nalmefene
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Describe absorption of opiods placed in the epidural space.
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Opiods placed in the epidural space undergo significant systemic absorption and passage into the subarachnoid space.
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Describe absorption of opiods placed in the epidural space.
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Opiods placed in the epidural space undergo significant systemic absorption and passage into the subarachnoid space.
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What influences penetration of opiods in the dura?
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Lipid solubility of the agent (ie. fentanyl and sufentanil pass across the dura much more rapidly than morphine)
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Compare epidural and intramuscular injections of equivalent doses of opiods.
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Epidural administration of morphine, Fentanyl, sufentanil produce opiod blood concentrations simaler to that of IM injections of equal dose
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Is vascular absorption after intrathecal administration significant?
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no
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What determines rate or amount of cephalad (toward head) movement of opiods in CSF? Give Example.
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depends on lipid solubility
example: Lipid-soluble opiods (fentanyl, sufenta), are limited in cephalad migration by uptake into the spinal cord, whereas less lipid-soluble morphine remains in CSF for transfer to more cephalad locations. |
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What are the Side Effects of Neuraxial Opiods?
Which are most common? |
table 10-3
1) Pruritis 2) N/V 3) Urinary retention 4) Depression of ventilation 5) Sedation 6) Central Nervous system excitation 7) Activation of latent viral infections 8) Sexual dysfunction 9) Water Retention most common=1-4 |
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What is the primary cause of opiod sideffects?
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SE result from the presence of the drug in the CSF or systemic circulation, or both
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List and describe the stages of depression of ventilation associated with neuraxial injection of opiods.
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1) Early: occurs within 2 hours
2) Delayed: occurs 6-12 hours after epidural or intrathecal administration of morphine. |
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What opiod receptors are present in the spinal cord?
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Opiods placed in the epidural or subarachnoid space bind to mu erceptros in teh substantia gelatinosa of the spinal cord.
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Contrast analgesia obtained by neuraxial opiods vs iv opiods
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Unlike IV opiods, analgesia produced by spinal or epidural (neuraxial) opiods is not associated with sympathetic nervous system denervation, skeletal muscle weakness, or loss of proprioception.
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Analgesia in Neuraxial opiods is dose related compare epidural and subarachnoid doses and effects
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epidural dose is 5 to 10 times that of subarachnoid dose, adn specific for visceral rather than somatic pain
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Describe the steps following action of epidural placement of opiods which result in analgesia
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1) Diffuses across Dura
2) Binds to Mu opiod receptors on the spinal cord 3) absorbs systemically to produce effects simalar to that of IV administration |
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What is the difference in poorly vs highly lipid soluble agents?
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Poorly lipid soluble opiods (morphine) result in a slower onset of analgesia but have a longer duration of action than lipid soluble (fent, sufenta)
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List the Factors that increase the risk of Depression of Ventilation
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1) High opiod dose
2) Low lipid solubility of opiods 3) Concomitant administration of parenteral opiods or other sedatives 4) Lack of opiod tolerance 5) Advanced age 6) Patient position 7) Increased thoracic pressure |
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List signs and symptoms of respiratory depression in neuraxial opiods.
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*note-arterial hyoxemia and hypercarbia may develop despite a normal breathing rate*
1) Pulse Ox 2) Capnography 3) Hypoventilation 4) Decreased LOC caused by hypercarbia (most reliable according to book) |
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reversal agent in OD of neural axial opiods?
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Naloxone (O.25 mcg/kg/min) IV
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List opiod agonists and their half life in hrs.
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Morphine, 1.7-3.3
memperidine, 3-5 fentanyl, 3.1-6.6 sufentanil, 2.2-4.6 alfentanil, 1.4-1.5 remifentanyl, 0.17-0.33 |
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What is the most notable feature in teh clinical use of Opiods?
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The extraordinary variation in dose requirements to achieve analgesia
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Describe the effects of morphine
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analgesia, euphoria, sedation, decreased ability to concentrate
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Describe the effects of morphine
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analgesia, euphoria, sedation, decreased ability to concentrate
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How does morphine effect the sensaton of pain?
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Increases threshold to pain, modifies perception of noxious stimuli so it is no longer experienced as pain.
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On which type of pain does morphine work best?
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Continuous, dull pain rather than sharp, intermittent pain, pain arising from the viscera, as well as from skeletal muscles, joints, and integumental structures.
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When should opiods be administered to produce the most prominent analgesia?
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Prior to painful stimulus, (preemptive analgesia). or before acute surgical stimulus
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What can occure if Morphine is administered in the absence of pain
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dysphoria rather than euphoria
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How are opiods cleared primarily
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hepatic metabolism
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List onset, peak effects, and duration of action of morphine (IM vs IV)
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MS:
IM-onset 15-30 min -peak 45-90 min -duration of action 4 hours IV-peak 15-30 min |