Pain Management Flashcards
Which fibers evoke sharp, well localized pain?
myelinated A delta fibers
large diameter
Which fibers evoke dull, aching, poorly localized pain?
unmyelinated C fibers
small diameter
Which cognitive and behavioral functions decrease pain?
Which worsen pain?
relaxation
meditation
distraction
guided mental imagery
anxiety
depression
Nonpharmacologic therapies for pain management
physical manipulation
heat/cold
massage
exercise
transcutaneous electrical nerve stimulation (TENS)
cognitive, behavioral, social aspects
Naturally occurring opioids
morphine
codeine
heroin
Semisynthetic agents
hydromorphone oxymorphone levorphanol hydrocodone oxycodone
Synthetic agents
meperidine fentanyl methadone pentazocine butorphanol nalbuphine buprenorphine tramadol tapentadol
What is the effect of the acetyl group in aspirin? (vs other salicylates)
antiplatelet
other salicylates do not alter platelet function
Maximal daily dose of acetaminophen: general population
no more than 3mg/d
Nonopioid Analgesics: agents
salicylates (aspirin, choline and Mg salicylate, diflunisal)
acetaminophen
anthranilic acid (mefenamic acid)
indoleacetic acid (etodolac)
phenylacetic acids (diclofenac potassium, diclofenac epolamine, diclofenac sodium)
proprionic acids (ibuprofen, ketoprofen, naproxen, naproxen sodium)
pyrrolacetic acid (ketorolac)
cox 2 selective (celecoxcib)
Ibuprofen: maximum daily dose: pediatrics
40mg/kg/d
over 6months of age
Ibuprofen: maximum daily dose: inflammatory
3200mg/d
Ibuprofen: maximum daily dose: analgesic/fever/dysmenorrhea
1200mg
What is the maximum dosing of ketorolac?
5 days
NSAIDs: ADE, monitoring parameters
upper GI bleed (CBC, stool guaiac)
acute renal failure (serum creatinine)
Maximal daily dose of acetaminophen: elderly population
no more than 2mg/d
Acetaminophen: ADE, monitoring parameters
hepatotoxicity (ALT/AST, PT/INR, albumin, serum concentration)
Agents with relative histamine release
morphine
codeine
meperidine
What is the drug of choice in severe pain?
morphine
Morphine vs. Hydromorphone
hydromorphone is more potent than morphine
Codeine: indications
mild-mod pain and cough suppression
**weak analgesic – use w/ NSAIDs, ASA or APAP
Codeine: analgesic prodrug: what does this mean
requires liver (CYP450 2D6) to be converted to morphine (rate limiting step)
Meperidine: contraindications
do not use in renal failure
Which opioid analgesic produces mydriasis?
meperidine
**most opioids cause miosis
Meperidine: ADEs
tremors
myoclonus
seizures
Which route of administration is contraindicated for fentanyl?
transdermal
do not use transdermal in acute pain
Methadone: ADEs
sedation
QT prolongation
**avoid dose titrations more frequently than every 2wks
Which drugs can precipitate withdrawal in opiate dependent patients?
agonist/antagonist agents: pentazocine butorphanol nalbuphine buprenorphine
Naloxone may not be effective in reversing respiratory depression for which drug?
buprenorphine
Which populations need decreased doses of tramadol?
renal impairment (CrCl < 30) elderly (75+yo)
**risk of seizure, serotonin syndrome, hypoglycemia
Opioids: ADEs
respiratory depression (high risk: OSA, COPD) constipation sedation (dec over time) N/V (dec over time) tolerance dependence addiction/abuse/pseudo-addiction histamine release (urticaria, pruritus, bronchospasm) inc sphincter tone hypogonadism (long term use)
Codeine: do not use in…
children
breastfeeding women
Meperidine: do not use bc…
toxic metabolite (normeperidine) – accumulation can lead to seizures and renal insufficiency
Naloxone: special instructions
repeat dose bc duration of opioid may outlast naloxone
call 911!
Neuropathic Pain: adjunctive therapy agents
anticonvulsants (gabapentin, pregabalin) TCA SNRI (duloxetine) opioids topical analgesics (lidocaine, NSAIDs, salonpas, tiger balm)
Gabapentin, Pregabalin: MOA
dec excitatory NT through Ca channels (alpha 2)
**pregabalin is more selective than gabapentin
Gabapentin: ADEs
dizziness, fatigue peripheral edema tremoer, headache, ABNORMALITY IN THINKING, amnesia ATAXIA, ABNORMAL GAIT weight gain
Pregabalin: ADEs
PERIPHERAL EDEMA
weight gain
tremor
dizziness, ataxia
Duloxetine: MOA
potent inhibitor of neuronal serotonin and NE reuptake
Duloxetine: ADEs
headache, drowsiness, fatigue
nausea, xerostomia
insomnia, agitation
Regional Analgesia: ADEs
CNS excitation and depression
CV effects
Ziconotide: MOA
selectively binds N type voltage sensitive Ca channels
blocks excitatory NT release and reduces sensitivity to painful stimuli
Ziconotide: ADEs
confusion, dizziness, hallucinations
urinary retention
sedation, somnolence, nausea, headache
Guidelines for Management of Low Back Pain
initially: nonpharmacologic therapy
inadequate response:
- acute: NSAIDs, skeletal muscle relaxants
- chronic: NSAIDs (2nd: duloxetine, tramadol)
opioids if other agents failing, benefits>risks
Neuropathic Pain: pharmacologic management
first line: AEDs, SNRIs, TCAs, lidocaine patch
second line: opioids, central analgesics (tramadol)
third line: capsaicins
**NSAIDs and acetaminophen rarely effective
True Opioid Allergy: MOA, presentation
IgE or T cell mediated
BRONCHOSPASM, angioedema
hives, inc HR, low BP
Opioid Pseudoallergy: MOA, presentation
caused by histamine release from mast cells (nonimmunologic effect)
itching
flushing
sweating
hives, inc HR, low BP
Choosing an analgesic: options for a patient with a pseudoallergy
nonopioid analgesic (acetaminophen, NSAID)
more potent opioid less likely to release histamine
avoid codeine, morphine, meperidine
consider concurrent administration of an antihistamine
dose reduction (if tolerated)
Choosing an analgesic: options for a patient with a true allergy
nonopioid analgesic (acetaminophen, NSAID)
opioid of a different class
Opioid potency: lowest to highest
meperidine < codeine < morphine < hydrocodone < oxycodone < hydromorphone < levorphanol < fentanyl
Phenylpiperidines: agents
meperidine
fentanyl
sufentanil
remifentanil
Diphenylheptanes: agents
methadone
propoxyphene
Morphine group: agents
morphine codeine hydrocodone oxycodone oxymorphone hydromorphone nalbuphine butorphanol levorphanol pentazocine
