Local anesthetics and analgesics

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Local anesthetics and analgesics
2013-12-08 16:09:26

OBIO Exam 3
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  1. Anesthetics with high potency?
    Bupivicaine and Tetracaine

    High pKa, moderate rate of onset but LONG duration
  2. Two theories of mode of action of anesthetics?
    1. Membrane expansion theory: lipophilic  anesthetics inciorporate themselves into membrane

    • 2. (Major) receptor mechanism: physical occulsion of na channel
    •                   a. allosterically mediated
    •                   b. distort local electrical field
  3. The blockade of Na conductance is the basis of local anesthetic action
  4. What is an additional contributing mechanism to blockade of Na conductance?
    Physiochemical interaction of the base form with membrane
  5. What is the differential nerve blockade by anesthetics?
    Autonomic loss first (that is why we give epi to constrict because autonomics shutdown)

  6. What are the factors contributing to the differential nerve blockade?
    • 1. fiber length
    • 2. use-dependent block
    • 3. peripheral nerve organization
    • 4. local anesthetic selectivity
  7. How to delay anesthetics rate of absorption?
    Vasoconstrictors slow

    Sympathomimetic agents are topically ineffective
  8. Distribution of local anesthetics?
    • 1.bind to plasma proteins
    • 2. Unbound diffuses to tissues freely
    • 3. Enter CNS and can cross placenta
    •              a. lido, prilo, etido Cat B
    •              b. Mepiv, Bupi Cat C
  9. Metabolism of local anesthetics?
    Esters by plasma cholinesterase

    Amides by hepatic oxidase system (lido T1/2 1.5-3.5hrs but Tetra is 25 minutes because it has an ester)

    Metabolite of prilocaine, articaine, benzocaine (O-toluidine) can cause methehemeglobinemia

    Lido has some metabolites too that are toxic
  10. Excretion of local anesthetics?

    Inversely to their protein binding

    Inversely to the pH of urin
  11. Cardivascular toxicity of local anesthetics?
    Lipophilic ones like etido and bupivacaine

    depress myocardial contractility

    note: locally do affect myogenic activity and autonomic tone
  12. Dosage calculation, Clark's rule?
    Based on child's body weight

    Or Young's rule which is based on patient's age
  13. Maximum does for lido with epi?
    7mg/kg max of 500mg

    lido no epi 3mg/kg 300mg max
  14. What is inside a carpule of anesthetic?
    • 1. Local anest
    • 2. Vasoconstrictor
    • 3. Metabisulfite (only if epi present)
    • 4. Isotonic NaCl
    • 5. HCL or NaOH to adjust pH
  15. Drug interactions and local anesthetics?
    CNS acting agents can cause permanent deficits
  16. Drug interactions with epi in anesthetic?
    potential elevation of BP with tricyclic antidep

    NO interaction with epi and MOA

    also...alpha blocker (epi reversal=hypotension)

    beta blocker (vasoconstriction with epi causing hypertension)
  17. What is Oraverse?
    alpha-adrenergic blocking agent, vasodilates removes anesthetic quicker from site

    BUT will not reverse CNS and cardio effects
  18. Adverse effects of articaine and prilocaine?
  19. Effects of aspirin?
    Antipyretic, analgesic, antiinflammatory, antiplatelet

    Can cause analgesic nephropathy, reye's syndrome, GI bleeding
  20. Dolobid?
    Diflunisal: derivative of salicylic acid

    not metabolized to salicylate

    extended duration
  21. What does chronic toxicity of aspirin look like?
    Tinnitis, nausea, headache, hyperventiliation, confusion

    IRREVERSIBLE binding to COX
  22. Acute toxicity of aspirin?
    Hyperthermia, respiratory alkalosis, acidosis

    TX: alkalization of urine, gastric lavage, respiratory support
  23. Aspirin intolerance signs?
    Rhinitis to severe asthma because lipoxygenase pathway is predominating

    DO NOT switch to NSAIDs since they are cross-sensitive
  24. Tylenol indications?
    antipyretic, analgesic, but little antiinflammatory effects (that is it is good for aspirin sensitive folks, no COX blocking)
  25. Adverse effects of tylenol?
    Hepatotoxicity (metabolite n-acetyl-benzoquinoneimine), max 4g/day

    Tx: gastric lavage, within 36hrs give n-acetylcysteine
  26. NSAIDs indication?
    like aspirin

    adverse effects like aspirin but REVERSIBLY binds to COX

    ALL NSAIDS have ceiling effect! you give more and less therapy but more side effects
  27. Contraindications of NSAIDs?
    Renal disease

    Hematologic malignancies w/thrombocytopenia

    Asthma/nasal polyps
  28. Ketorolac?
    NSAID mainly formulated for IV use

    no more than 5 days due to risk of renal toxicity, has anitplatelet activity
  29. Plant of opium and percent drugs?
    Papaver somniferm

    10-12% morphine

    .5-1% codeine
  30. What are opiates?
    alkaloids derived and isolated from opium
  31. What are opioids?
    Morphine like pharm properties but not derived from opium

    This and opiates are now called opioid analgesics
  32. Name naturally occuring opiates?
    Opium, morphine, codeine
  33. Name semisynthetic opioids?
    Heroin, hydromorphone, hydrocodone, oxycodone
  34. Synthetic opioids (fully)?
    Meperidine, Fentanyl, sufentanyl (extremely potent, the last two)
  35. Name narcotic antagonists?
    Naloxone, Naltrexone
  36. Endofenous opioid peptides, rank in order of size?
  37. Opioid receptors?
    Four types, many subtypes

    • Main is mu
    •  mu1 is supraspinal
    •  mu2 is spinal analgeisa
  38. Where do opioids provide analgesia?
    Central and peripheral (not neuropathic or sharp)

    no ceiling effects

    effective against continuous, dull, aching pain
  39. What does aging do to pharm effects of opioids?>
    • 1. dec sensitivity to pain
    • 2. reduced ability to clear morphine
    • 3. more pain relief with dose compared to younger patient
  40. Respiratory effects of opioids?
    Dec in tidal volume and rate

    dec response of brainstem to CO2 tension

    supress respiration
  41. cough suppression and opioids?
    Side effect, but wanted

    codeine and dextrometrophan

    supression is lower does than needed for analgesic eeffect or respiratory effect
  42. Pupillary constriction and opioids?
    No tolerance to this excitation

    pinpoint pupils in addicts
  43. Nausea and opioids?
    Vomiting, stimulate CTZ in medulla causing emesis

    vestibular component, if patient lays down all good but not when walking
  44. Opioids and GI tract?
    Constipation, inc sm tone and dec propulsive motility

    Billary spasms, inhibits intestinal hypersecretion (great for diarrhea tx)
  45. Opioids and other smooth muscles?
    Dec urine flow due to effects on sm cells of ureter, bladder, uterus

  46. Opioids and asthma?
    May propentiate, due to histamine release
  47. Opioids and CV system?
    Dec BP due to hypoxia (vasodilation to counteract)

    Dec peripheral vascular tone (helps in pulmonary edema)

    Orthostatic hypotension

    Cerebral vasodilation
  48. Therapeutic use for morphine?

    Pulmonary edema

    Inducing sleep
  49. Therapeutic use for codeine?
    Inc oral effectiveness (60% bioavailable)due to methoxy group

    analgesic postoperative (30-60mg), antitussive (15-20mg)

    10 morphine=120mg codeine

    biotransformation is inhibited by cimetidine or antidepressants

    onset 30-45mins
  50. Mepiridine side effects?
    Poor CV stability during IV

    Acute intoxication is CNS excitation (tremors, convulsions opposite of coma and stupor with morphine)

    must be given IV, poor orally
  51. Mepiridine and pupils and billary?
    Less pupillary and billary due to atropine like activity
  52. Therapeutics of fentanyl?
    80-100 times more potent due to lipid soluble, short duration of action

    ADVantage: cardiac stability, reduces endocrine response to surgery
  53. Naloxone therapeutics?
    Short acting IV admin

    antidote for respiratory depression
  54. Naltrexone therapeutics?
    Long acting- oral admin

    48-72 hrs effectiveness
  55. Therapuetics of pentazocine?
    agonist at K and partial agonist or weak antagonist at mu recpetors

    new drug Talwin has this and naloxone to prevent injection abuse.
  56. Side effects of pentazocine?
    Less potent than morphine

    Can increase HR and BP, unlike other opioids

    does not cause as severe resp depression
  57. Therapuetics of Tramadol?
    weak Mu agonist and reuptake of NE and 5HT

    mod-severe pain, good orally

    n/v and drowsiness common side effects
  58. Therapeutics of Tapentadol?
    Opioid agonist and inhibits NE reuptake

    schedule II drug

    not first line drug
  59. Nitrous oxide therapuetics?
    Analgesic: mobilizes endogenous opioids

    Anxiolytic: GABA inhibition
  60. Benefits of NO2?
    Rapid induction and recovery

    High MAC 100% low potency, can be titrated

    protects cough reflex
  61. Adverse effects of NO2?
    n/v worsened by longer duration, inc concentration, or fluctations of administration

    fasting not necesssary but light meal recommeneded
  62. What is a sedative?
    drowsiness, relaxation, calmness, dev motor activity with no loss of consciousness
  63. What is hypnosis?
    loss of unconsciousness that resembles natural sleep, dec motoractivity, impaired sensory responsiveness
  64. Which benzos used for surgical adjuncts in conscious sedation?
    Diazepam and Midazolam
  65. Which benzos to treat skeletal m uscle spasm?
    Diazepam and chlordiazepoxide
  66. Which benzos used to treat tension, insomnia, and anxiety?
    alprazolam, diazepam, triazolam, oxazepam
  67. Skeletal muscle spasms and site of action by benzos?
    site of action is subcortical but evidence of spinal interneurons are also affected
  68. All benzos cause anterograde amnesia
  69. Side effect of midazolam?
    respiratory depression and apnea, worse with opioid
  70. Adverse effects of benzos?

    CNS depression (elderly more susceptible)

    inc incidence of nightmares, hyperactivity, insomnia

    paradoxical excitement
  71. What antihistamines are given to children?
    Hydroxyzine and Promethazine,

    Antiemetic, antihistamines

    hydroxy: also anticholinergic
  72. Psychosocial or behavioral factors may contribute to the perception of chronic craniofacial or dental pain.