Opioids and Anti-Emetics

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ariadne9
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224383
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Opioids and Anti-Emetics
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2013-06-24 19:53:31
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BC Nurse Anesthesia NU 493
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Opioids and Anti-Emetics
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  1. opioid
    exogenous substances, both natural and synthetic, that bind to opioid receptors and produce "morphine like" effects
  2. Describe the general effect of opioids.
    Analgesia without loss of touch, proprioception, or consciousness (except in large doses)
  3. What risks are associated with opioid antagonists?
    -SNS stimulation due to analgesia reversal, pulmonary edema, arrhythmias, HTN, tachycardia.
  4. What structural class does morphine belong to?
    -phenanthrene (T shaped)

    -Per Hemmings it's also a benzylisoquinoline
  5. What structural class does fentanyl belong to?  What other drug is in this class?
    -phenylpiperidine

    -meperidine
  6. What's the difference btw a semisynthetic and synthetic opioid?
    Semisynthetic- substitutions of morphine molecule, (ex: codeine, hydromorphone, oxycodone, hydrocodone)

    Synthetic- completely synthesized, not just morphine modified (ex: fentanyl, meperidine)
  7. What receptors do the opioids work on?
    mu1, mu2, kappa, delta, (sigma- but probably not an opioid receptor)
  8. Where are the receptors that the opioids work on located?
    • -CNS, mostly brainstem and spinal cord
    • -Periphery
  9. How do opioids produce their analgesic effects?
    • -They directly inhibit ascending transmission of information (pain) from the spinal cord and interrupt the pain circuit
    • -Inhibit the release of "substance P" from primary sensory neurons in the dorsal horn, mitigates transfer of painful stimuli to brain
    • -Changes the affective response to pain, may not completely block all pain
  10. What type of receptors are the opioid receptors?
    G (guanine) protein-coupled (like muscarinic, Ach, GABA, adrenergic)
  11. What happens when the opioid agonist binds to the receptor? (On a cellular level)
    Inhibitory effects: inhibition of adenyl cyclase which leads to increased outflow of K+ and decreased inflow of Ca++, this make the cell hyperpolarized, and cause a decrease in NT release (less pain)
  12. What receptors are associated with respiratory depression and physical dependence?
    mu2 and delta
  13. What receptor is associated with muscle rigidity?
    mu
  14. Are opioids basic or acid drugs?
    Basic
  15. pKa of all opioids (except alfent and remifent)? which form predominates?
    pKa > physiologic pH

    ionized form (BH+)
  16. pKa of alfent, which form predominates?
    6.5

    nonionized (B)
  17. pKa of remifent, which form predominates?
    7.1

    nonionized (B)
  18. What does a drug's partition coefficient tell us? What else is it called?
    Lipid solubility

    n-octanol / water partition coefficient
  19. List the following drugs from least lipid soluble to most: meperidine, morphine, fent, remifent, alfent, sufent
    morphine (1.4), remifent (17.9), meperidine (38.8), alfent (130), fent (860), sufent (1778)
  20. What is first pass uptake by the lungs?
    Significant amounts of lipid-soluble opioids can be retained by the lungs.
  21. What factors decrease first pass uptake by the lungs?
    • decreased uptake is caused by:
    • -prior accumulation of another drug
    • -inhalation anes (it's another drug)
  22. What factors increase first pass uptake by the lungs?
    history of tobacco use
  23. Why does alfent have a more rapid onset and short duration of action than fent even tho it is less lipid soluble?
    • -Alfentanil has a low pKa (pKa < pH), so nonionized form predominates at physiologic pH.
    • -It's low lipid solubility gives it a smaller Vd
  24. What kinetic property goes hand in hand with onset of action?
    pKa
  25. What is "latency to peak effect"?
    slow effect site equilibration time
  26. Rate the following 3 drugs from slowest to fastest effect site equilibration time: fent, sufent, alfent
    Sufent, fent, alfent
  27. What organ are the opioids dependent on for biotransformation?
    The liver; they have high hepatic extraction, clearance is dependent on hepatic blood flow
  28. How is remifent metabolized?
    ester hydrolysis, metabolized in the plasma
  29. Does a pseudocholinesterase deficiency affect metabolism of remifent?
    No
  30. What is morphine's active metabolite?  Is it more or less potent than morphine?
    morphine 6 glucuronide

    More potent and longer lasting than morphine
  31. What is meperidine's active metabolite?  Is it more or less potent than meperidine?
    Normeperidine

    As potent as meperidine
  32. What's a potential SE of normeperidine?
    CNS stimulation- myoclonus and seizures
  33. Rate the following drugs from least protein bound to most: morphine, remifent, alfent, sufent, meperidine, fent
    morphine (35%), meperidine (70%), fent (84%), alfent (92%), remifent (66-93%), sufent (93%)
  34. What SE do the opiates typically have on the CV system?
    generally stable
  35. What effect do morphine and meperidine have on the CV system?
    -They both cause histamine release which causes hypotension and decreased SVR

    -Meperidine is structurally related to atropine so it can cause an increased HR
  36. What effect can fentanyl have on the CV system?
    At high doses it can cause vagus mediated bradycardia
  37. What SE do the opiates typically have on the respiratory system?
    • -RR depression (more than decrease in TV)
    • -Decreased response to CO2, decreased hypoxic drive, chest wall rigidity
  38. Is the chest wall rigidity only limited to the chest?
    • -No, it can affect all striated muscle.
    • -Can possibly prevent ventilation 
    • -Can affect larynx and pharynx
  39. Chest wall rigidity is most associated with what opioids?
    Highly lipid soluble opioids like fentanyl
  40. What SE do the opiates typically have on the CNS?
    • -Decreased CBF, ICP, CMRO2 but less than the benzos or barbs
    • -Stimulates the chemoreceptor trigger zone (N/V)
  41. What SE do the opiates typically have on the GI system?
    Increased gastric emptying time, decreased peristalsis, biliary spasm
  42. What SE do the opiates typically have on the endocrine system?
    Block stress hormone response more than the volatiles.  Blocks catecholamines, cortisol, and ADH.
  43. Which opioid has the least effect on the common bile duct pressure and might be desirable in a chole with bile duct exploration?
    Demerol; all the opioids increase common bile duct pressure and hence delay gallbladder emptying, but demerol does this to a lesser degree.  Opioids should be avoided, but if you had to give one, give demerol.  
  44. What opioid is the prototype and standard?
    morphine
  45. What type of pain is morphine best for?
    continuous dull pain, best given preemptively
  46. Why does morphine take 15-30 mins to peak, with only 0.1% reaching the CNS at peak plasma concentrations?
    Morphine is poorly lipid soluble and has a high degree of ionization.  
  47. Other than analgesia, what's another use of morphine
    Pulmonary edema as it decreases the sensation of SOB
  48. What are major SE of morphine? (think respiratory, immune, and cardiac)
    • -Respiratory depression
    • -Histamine release
    • -venous pooling, decreased CO, orthostatic hypotension, possible bradycardia
  49. What's the peak of morphine?
    5-20 mins
  50. What's the onset of morphine?
    < 1 min
  51. What's the duration of morphine?
    2-7 hrs
  52. What's the normal range of analgesic IV doses for morphine?
    1-15 mg
  53. List the elimination half time of the following agents from shortest to longest: morphine, meperidine, fent, alfent, sufent, remifent
    remi, alfent, morphine, sufent, meperidine, fent
  54. What structural classification is meperidine derived from?
    phenylpiperidine (fentanyl family)
  55. What drug (non opioid) is meperidine structurally similar to?
    Atropine, hence can cause increases in HR
  56. 10 mg morphine = ____ mg meperidine?
    100
  57. What effect does meperidine have on the heart that is unique to the opioids?
    decreases myocardial contractility
  58. What's the only opioid that causes an increase in HR?
    meperidine, all the other opioids decrease HR
  59. Which 2 opioids have the greatest effect on MAP?
    remifent and alfent
  60. Do the opioids cause bronchodilation?
    No.  Morphine and meperidine cause histamine release which would cause bronchoconstriction.
  61. Best use for meperidine?  What receptor?
    Post-op shivering.  Kappa receptors.
  62. What drug class should be avoided with meperidine?  Why?
    MAOI's due to serotonin syndrome
  63. Cause and s/sx serotonin syndrome
    • -Due to excess serotonin in the CNS
    • -confusion, fever, shivering, diaphoresis, ataxia, diarrhea, myoclonus
  64. Analgesic dosing for meperidine?
    12.5-100 mg
  65. Onset, peak, and duration of meperidine?
    • Onset < 1min
    • Peak < 1 hr
    • Duration 2-4 hours
  66. What's a benefit of hydromorphone (SE)?
    -Less opioid related SE than morphine
  67. 10 mg morphine = ____ mg hydromorphone
    2
  68. hydromorphone Vd
    4 L/kg
  69. hydromorphone percent protein bound
    8-20%
  70. hydromorphone biotransformation site
    liver
  71. Does hydromorphone have active metabolites?
    Yes, dihydromorphine and dihydroisomorphine
  72. What's the issue with giving hydromorphone to pts with RF?
    The inactive metabolite, hydromorphone-3-glucuronide can accumulate with RF and cause neuroexcitation and cognitive impairment
  73. Vd, list the following drugs from smallest to greatest: fent, remi, alfent, sufent, morphine, meperidine
    alfent (27 L), remifent (30 L), sufent (123 L), morphine (224 L), meperidine (305 L), fent (335L)
  74. What 2 opioid receptors are associated with low abuse potential and miosis?
    mu1 and kappa
  75. What opioid receptor is associated with marked constipation?
    mu2
  76. What 2 opioid receptors are associated with urinary retention?
    mu1, delta
  77. Usual analgesic dosing of hydromorphone?
    0.5-2 mg
  78. Onset, peak, and duration of hydromorphone
    • Onset 15 mins
    • Peak 30-60 mins
    • Duration 4-5 hrs
  79. 10 mg morphine = _____ mcg fent (____ mg)
    100 mcg, 0.1 mg
  80. Why does fentanyl have a faster onset and shorter apparent duration than morphine?
    • It's more lipid soluble, so it gets to the CNS faster, has a large Vd.
    • It appears to have a shorter duration than morphine because it gets taken up by the fat and lungs
  81. What drug undergoes a large 1st pass pulmonary uptake?
    fentanyl, 75% of the initial dose undergoes 1st pass uptake which limits the amount of initial dose reaching the systemic circulation
  82. Why factors contribute to fentanyl's long context-sensitive half time?
    • Large Vd
    • Lipid soluble
    • Decreased clearance
  83. Context-sensitive half time: Rank the following drugs from shortest to longest- fent, alfent, remifent, sufent
    remifent, sufent, alfent, fent
  84. Compare the effect site equilibration time of the following drugs: morphine, alfent, fent
    alfent> fent> morphine
  85. Does fentanyl have an active metabolite?  How does its potency compare to fentanyl?
    Yes, norfentanyl.  Less analgesic potency than fentanyl.  
  86. Advantages in terms of SE with fentanyl
    No myocardial depression or histamine release, suppresses the stress response
  87. Bad SE of fentanyl
    • Possible bradycardia due to vagostim
    • Chest wall rigidity
  88. fentanyl premedication / analgesia dosing
    25-100 mcg IV
  89. induction dose of fentanyl
    -with a hypnotic
    -with 70% N20
    -as high dose opioid
    • -hypnotic 1.5-5 mcg /kg
    • -70% N20 8-23 mcg / kg
    • -high dose opioid 50 mcg/ kg
  90. Onset, peak, and duration of fentanyl
    • Onset 30 sec
    • Peak 5-15 mins
    • Duration 30 mins to 1 hr
  91. What was innovar?
    fentanyl and droperidol
  92. 10 mg morphine = 100 mcg fentanyl = ____ mcg sufent
    5-10 mcg
  93. Why does sufent have a smaller Vd and shorter elimination half time than fentanyl?
    It is more ionized?? and more protein bound
  94. Where is sufent metabolized?
    liver
  95. sufent SE
    Decreased HR due to vasodilation and sympatholysis but HD stability prevails
  96. induction dose of sufent
    -with a hypnotic
    -with 70% N20
    -as high dose opioid
    • -hypnotic 0.1- 1 mcg / kg
    • -70% N20  1.3-2.8 mcg /kg
    • -high dose opioid  10-30 mcg / kg
  97. Intermittent bolus dose of sufent
    5-20 mcg
  98. Onset, peak, and duration of sufent
    • onset 1-3 mins
    • peak 3-5 mins
    • duration 30 mins to 1 hr (apparent clinical duration, not elimination half time)
  99. 100 mcg fent = ____mcg alfent
    500
  100. alfent pka, what form of the drug prevails
    • 6.8
    • Nonionized- B
  101. What factors contribute to alfent having a fast onset and offset?
    pKa of 6.8 means it is mostly in nonionized form, less lipid soluble than fentanyl
  102. alfent % protein bound 
    92%
  103. Does alfent have active metabolites?
    no
  104. Alfent SE
    • -Chest wall rigidity in 90-100% of pts at does of 150-175 mcg/kg
    • -? more hypotension and bradycardia than fentanyl or sufent
    • -? more N/V
  105. induction dose of alfent
    -with a hypnotic
    -as high dose opioid
    • hypnotic 10-50 mcg/kg
    • high dose opioid 120 mcg/kg
  106. alfent intermittent bolus dose
    250-500 mcg (5-10 mcg / kg)
  107. alfent
    peak, onset, and duration
    • onset < 1 min
    • peak 1-2 mins
    • duration 10-15 mins
  108. Why is remifent so short acting?
    It's metabolized by blood and tissue esterases (not pseudocholinesterase)
  109. Does remifent have a large or small Vd?
    small, hence fast offset
  110. induction dose of remifent
    It can't be used for induction alone
  111. Dosing of intraop analgesia of remi
    continuous infusion at 0.3 to 1 mcg /kg/ min
  112. What needs to be considered with emergence / post-op when using remi
    If pt expected to have a lot of post-op pain you need to give a longer acting opioid
  113. What receptors do the opioid partial agonists work on?
    mu and kappa
  114. What are some examples of opioid partial agonists?
    nalbuphine, butorphanol, buprenorphine, pentazocine
  115. How does an opioid partial agonist work?
    Binds to the receptor to produce a limited effect (need more of the drug and it can't reach full effect)
  116. When could an opioid partial agonist be used?
    • -Reserved for patients who can't tolerate pure opioid agonists
    • -Can reverse respiratory depression from other opioids while maintaining some level of analgesia
    • -Ceiling effect, increased dose does not increase the response
  117. Is remi's CSHT affected by infusion duration ?
    NO!
  118. What receptors can we target with drugs to treat PONV?
    • we can use antagonists for the following receptors:
    • dopamine, serotonin (5-HT), Ach (muscarinic), histamine
  119. Where does the CRTZ receive input from?
    medulla, GI tract, pharynx, mediastinum, visual center, vestibular portions of 8th CN (motion sickness)
  120. T or F, N/V is independent of the route of administration
    T
  121. Risk factors for PONV
    • -Age- pedi > adult, peaks in preadol. 
    • -in adulthood N/V decreases with age
    • -Gender- F>M, severity greater as well, increased during menses
    • -Body weight- obesity
    • -Non-smokers
    • -Opioids
    • -Motion sickness hx
    • -Anxiety
    • -Food- presence or absence
    • -Gastroparesis
    • -Surgery type
    • -N20
  122. Surgical procedures associated with increased N/V
    • -abd surgery
    • -females undergoing lap gyn procedures
    • -strabismus repair
    • -T & A
    • -orchiopexy
    • -middle ear surgery
    • -longer surgeries
  123. What post-op factors can influence N/V?
    Pain, movement, hypovolemia, hypoglycemia, hypoxia, opioid use, premature PO intake
  124. Serotonin is an endogenous vasoactive substance and NT involved with vasoconstriction, emesis, and pain transmission, T or F
    T
  125. In what areas of the body are large amounts of 5-HT3 found?
    CNS, GI tract, platelets
  126. What does MAO do to serotonin?
    Deactivates it into 5-HIAA
  127.  How do the 5-HT3 receptor antagonists work to decrease N/V
    • -Selectively block serotonin receptors with little to no effect on dopa receptors
    • -No effect on gastric motility for LES tone
  128. Examples and dosages of 5-HT3 receptor antagonists 
    • zofran 4-8 mg
    • dolasetron 12.5 mg
    • granisetron (kytril) 1 mg
  129. What class does reglan belong to and what receptor does it work on?
    • -Benzamide
    • -Dopamine
  130. What effects does reglan have?
    Selective cholinergic stim and GI prokinetic- increases LES tone, stim UGI tract motility, no effect on gastric acidity
  131. Reglan SE
    Abd cramping, hypotension, tachycardia, bradycardia, extrapyramidal reactions
  132. Reglan contraindications
    GI obstruction, malignant neurolept syndrome, head trauma (increased ICP), breast ca, don't combine with butyrophenones or phenothiazines, parkinsons dz
  133. T or F, drugs that are dopamine antagonists should be avoided in pts with parkinson's dz?
    T, ex: reglan, droperidol, phenothiazines
  134. Antiemetics associated with prolonged QT
    Dolasetron (5-HT3) and droperidol
  135. Butyrophenones
    • -Class of anti-psychotic drugs
    • -Dopa antagonist
    • -Anti-emetic
    • -Ex: droperidol
  136. Why is droperidol no longer used?
    BBW due to prolonged QT
  137. Phenothiazines
    • -Class of anti-psychotic drugs
    • -Dopa antagonist
    • -Anti-emetics
    • -Ex: compazine, thorazine, phenergan
  138. Phenothiazines contraind
    prolonged QT, malignant neurolept syndrome
  139. How are extra-pyramidal SE treated?
    With benadryl
  140. Use of dexamethasone for N/V
    • -Only effective if given pre-op
    • -decreases surgery induced inflammation
  141. Topical anti-emetic
    • Scop patch
    • apply before surgery
    • can cause dry mouth and dilated pupils

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