Pain & Drugs S2M1

  1. Epicritic
    Pain is easily discernible and well localized
  2. Protopathic
    Pain is not definitely localized & can only be described in a general way
  3. What are the four subclasses of chronic pain
    • Neuropathic
    • Mixed
    • Nociceptive
    • Viscera
  4. What is the difference between chronic and acute pain
    Chronic extends beyond the healing period, and has inadequate explanation for the presence and extent of the pain
  5. What is the role of A delta fibers in pain
    They are thin myelinated fibers that carry localized intense pain that is felt first (fast)
  6. What is the role of C fibers in pain
    They are small unmyelinated fibers that are slow, throbbing and long lasting
  7. What lamina does pain go through on the way to the brain
    • First order neuron: Lamina 2 (Substantia gelatinosa)
    • Second order neuron: Lamina 5 (Nucleus proprius)
  8. What is the role of Periaqueductal Grey (PAG) in pain
    They are usually inhibitory to Nucleus Raphe Magnus (NRM), but when activated they no longer inhibit, and the pain is reduced do to the NRM activation
  9. What does Nucleus Raphe Magnus system excite to reduce pain sensations
    Enkephalinergic interneurons in the spinal cord reducing the activity in afferent pain fibers
  10. How does Lidocaine work
    It is a nerve block
  11. What are the endogenous opiates
    • Enkephalin
    • - Endorphins
    • - Dynorphins
    • Opioids
    • Endomorphins
  12. What is lost in a unilateral lesion of the spinothalamic tract
    Contralateral loss of pain and temp sensation, symptoms appear 1-2 levels below the lesion
  13. What will result from a dorsal root lesion
    Ipsilateral loss of pain and temperature limited to the dermatomal levels of the lesioned roots
  14. What causes referred pain
    Neurons that are both nociceptive and and non-nociceptive are in lamina V and due to proximity, the brain gets the message wrong
  15. What is NMDA
    An amino acid derivative that acts as a specific agonist at the NMDA receptor mimicking the action of glutamate
  16. Wind up Theory
    Repeated activation of NMDA receptors causes increased response to the same stimulus, like kindling in seizures. Nerve damage can cause this effect.
  17. Allodynia
    Stimuli that is usually non-painful becomes painful
  18. Hyperalgesia
    General perception of painful stimuli becomes more intense
  19. TCA (anitdepressants) drugs have what contraindiction
    They should not be taken by those over 60 years old
  20. What are some effective local anesthetics
    • Capsaicin (lasts weeks)
    • Lidocaine (patch available)
    • Both can be used topically
  21. Which Anticonvulsant is preferred Gabapentine or Pregabalin and why
    Pregabalin requires a lower dose for the same effect
  22. TRPV1
    Also known as the capsaicin receptor and the vanilloid receptor 1
  23. What are the contraindictions of the anticonvulsants gabapentine and pregabalin
  24. What drug has been shown given to patients with herpes zoster can prevent postherpatic neuraglia
  25. Low doses of Ketamine during surgery has what effect
    It decreases the amount of Opioids needed
  26. Gabapentin and Pregabalin are anticonvulsants that have what MOA
    They block alpha-2-delta subunit calcium channels
  27. Ketamine and Dextromethorphan are used for what
    To help reduce the dose of Opioids needed
  28. What are the side affects of Opioids
    • Sedation
    • Confusion
    • Respiratory distress
    • Pruritis (severe itching)
    • Nausea and vomiting
    • Constipation
    • Miosis
  29. For what conditions can Opioid therapy be used
    • Acute pain
    • Cancer Pain
    • AIDS pain
    • Pain in advanced illnesses
  30. Opioids fall under a schedule II rating of controlled substances which means
    It has a high abuse potential with severe psychic or physical dependence
  31. Naloxone
    This is an Opioid antagonist
  32. Mu receptors
    A class of Opioid receptors
  33. Endorphin neurotransmitters use what type of receptors
    Mu receptors
  34. Enkephalin neurotransmitters use what type of receptors
    Delta receptors
  35. How do Opioids work on ascending fibers
    • They close voltage gated Ca2+ ions on the presynaptic neurons and block neurotransmitter release
    • They also hyperpolarize and inhibit postsynaptic neurons by opening K+ channels
  36. How do Opioids affect descending fibers
    They inhibit GABA's actions, GAbA normally inhibit neurotransmitters that prevent pain in the dorsal horn thus increasing the inhibition of pain
  37. Codeine and Acetaminophen together is equal to
    600mg of Ibuprofen
  38. Why is Fentanyl a popular choice for surgery, and what other uses does it have
    • It works fast & doesn't stay in the the system long
    • Nasal spray is used for break through pain
    • 80-500x more potent then morphine
  39. What is considered the Gold standard Opioid
  40. Why is Morphine not taken by pregnant women
    It reaches the fetus and can cause the baby to be dependent on Morphine
  41. What are some of the side effects of Morphine
    • Depression of Respiration
    • Euphoria
    • Drowsiness
    • Mental clouding
    • Nausea and vomiting
    • Constipation
  42. Why is pupillary constriction (Miosis) an important marker with a patient on Morphine
    When extreme, it can be a sign that the dosage is too high for the patient
  43. Meperidine
    Part of the strong agonist class of drugs and has a tenth the potency of Morphine, it should not be used for more then 48 hours

    Serotonin should not be taken with it because it raises Serotonin levels
  44. Methadone
    • Strong agonist that has a long half life
    • This is often used when there are limits to the use of morphine
  45. Oxycodone (Percodon & Oxycotin)
    • In the strong agonist group
    • Percodon is the short acting form
    • Oxytocin is the long acting form
    • Morphine substitute
  46. Hydrocodone
    • Moderate/Weak agonist
    • Used for moderate pain
  47. Vicodin
    Combination of Hydrocodon and Acetominophen
  48. Tapentadol
    • New mu-opioid strong agonist
    • Can substitute for morphine or oxycodone
    • Anti-inflammation effects
    • Less side affects
    • Less abuse likely
  49. Buprenorphine
    • Partial agonist
    • More potent then morphine (binds strongly)
    • Less likely to be abused
    • Less risk of respiratory depression
  50. Tramadol
    • Weak agonist
    • Same side effect issues as other Opioids
  51. Pentazocine
    • Mixed agonist
    • Used for mild to moderate pain
    • Little respiratory depression
    • Little physical dependance
  52. Buprenorphine, tramadol or pentazocine can by used for what condition
    Can help with withdrawal in physically dependent Opioid patient or addicts
  53. Naltrexone
    • Opioid antagonist
    • Orally given and has a long duration of action
    • Used in drug addiction treatments
Card Set
Pain & Drugs S2M1