Chapter 7: Pain Management Flashcards
Transduction of pain
Excitatory chemical neurotransmitters cause AP synapsing in dorsal horn of spinal cord
Transmission of pain
Neurotransmitters in dorsal horn depolarize the second order neurons causing transmission of information to the brain
Perception of pain
End result of pain transmission
modulation of pain
Main central inhibitory neurotransmitters include serotonin and norepinephrine–fight pain by increasing concentration in spinal cord and brainstem
Drugs recommended for mild to moderate pain
Acetaminophen and NSAIDs
Drugs recommended for moderate pain
Combo opioids, Ketorlac, Tramadol
Drugs recommended for severe pain
Opioids
-Morphine is gold standard
pure mu opioid agonists
Oxycodone, morphine, hydromorphone, oxymorphone, fentanyl
DOC for minor, noninflammatory pain
Acetaminophen
Drugs for chronic noncancer pain
NSAIDs and salicylates for chronic inflammatory conditions
Low dose opioids may be considered
Drugs for chronic cancer pain
Needs to be individualized
Opioids are mainstay in addition of nonopioids and coanalgesics
Acetaminophen
Prostaglandin inhibiton in CNS as COX-3 inhibitor
No anti-inflammatory, platelet or GI effects
Can cause fatal liver necrosis in toxic amounts >4000mg
NSAIDs
Anti inflammatory, antipyretic, analgesic
Block COX1 and COX2
Can cause GI side effects by blocking COX1
Opioids that are not excreted in active metabolites by kidneys
Fentanyl and methadone–DOC in renal failure
opioid DOC in liver failure
Fentanyl
Effects of opioids
Analgesia, respiratory depression, sedation, confusion, N/V, pruritus, miosis, constipation, urinary retention
Morphine
Undergoes significant first pass metabolism; crosses bbb, placenta and excreted in maternal milk
Binds to mu receptors in CNS
Prophylactic bowel regimens recommended
Codeine currently used as
Anti tussive primarily
Fentanyl
Alternative to morphine
Long acting transdermal patch available
Tramadol
Centrally acting, weak mu receptor agonist; inhibits NE and serotonin reuptake
Used for moderate to severe pain and neuropathic pain
Metabolized by CYP450 system
Methadone
Usually sued for treating opioid substance abuse
Mu receptor agonist and NMDA receptor antagonist
Metabolized by CYP450 system
Naloxone
Pure opioid antagonist used in opioid induced respiratory depression
Which form of laxative should not be used with opioids
Bulk forming laxatives–could cause bowel obstruction
Methylnaltrexone
Can treat opioid constipation as it binds to mu in the gut only and antagonizes
Withdrawal symptoms of opioid use
Tremors, sweating, fever, flu like symptoms, increased RR, persipiration, lacrimation, mydriasis, hot and cold flashes, anorexia
Benefits of coanalgesics seen in
Chronic pain, neuropathic pain, post op pain
Examples of coanalgesics
Antidepressants, anticonvulsants, sodium channel blockers, antispasmodics and antispastic agents
