Adjuvant or Adjunct Analgesics Flashcards
what are adjuvant analgesics?
drugs with a primary indication other than pain, but with analgesic properties under certain circumstances
what might adjuvant analgesics be used for?
acute pain
chronic pain
neuropathic pain
cancer pain
what can you use antidepressants for?
chronic pain
how do tranquilizers or anxiolytics modify pain signals?
target descending modulation of pain
how can sub-anesthetic doses of alpha 2 agonists be used?
added to epidural opioids or local anesthetics to prolong and increase analgesia for acute pain
postoperative or post trauma “micro dose” infusions
what is the NMDA receptor responsible for?
induction and maintenance of central sensitization (wind up)
what drugs are available for NMDA receptor antagonists?
ketamine
amantadine
memantine
how long can it take for the effects of amantadine to be notable?
up to 6 weeks
what can gabapentin do with preexisting neurologic weakness?
may exacerbate weakness
how does renal insufficiency affect gabapentin?
half life and accumulation of metabolites increases with renal insufficiency
is tramadol labeled for use in veterinary species?
no
how do tricyclic antidepressants work?
potentiate descending spinal inhibitory pathways by blocking presynaptic re-uptake of 5HT and norepinephrine
what are the types of adjuvant analgesics?
NMDA receptor antagonists: acute and chronic
antiepileptic drugs: acute and chronic
antidepressants: chronic
alpha2 agonists: acute
corticosteroids: acute and chronic
muscle relaxants: acute and chronic
bisphosphonates: chronic bone tumor pain
what are adjuvant analgesics used for?
chronic, maladaptive or cancer pain
sometimes acute
neuropathic and nociceptive pain
rarely used as first-line/alone
are adjuvant analgesics harder to dose?
often yes
how are corticosteroids used?
local irritations/inflammations, autoimmune disease, cancer, nerve damage
nerve or joint injection
what is ketamine useful for?
acute and chronic pain
prevents central sensitization
is ketamine given alone at a low dose CRI?
no
do low doses of ketamine cause dissociative effects?
no
what is amantadine studied to do?
chronic osteoarthritis pain
what is amantadine?
release of dopamine from nerve terminals
stimulation of norepinephrine response
weak NMDA antagonist
anticholinergic
what are the side effects of amantadine in animals?
appetite suppression
agitation
diarrhea
what is the metabolism of amantadine?
negligible
what can anti-epileptic (gabapentin) drugs be used for?
neuropathic pain
chronic pain
is the starting dose of gabapentin for seizures higher than that for pain?
yes
how long does gabapentin take to help?
can be 24 hours
chronic pain might take a long time
how often should gabapentin be given to a dog to maintain targeting plasma concentrations?
several times a day- 3 times
every 6 hours for cats
should you taper when you stop gabapentin?
yes
is gabapentin proven to work for acute pain?
no
do not know doses for acute or chronic pain
what does tramadol do?
weak mu opioid agonist
inhibitory effects on serotonin and norepinephrine reuptake
how is metabolism of tramadol to its active form achieved?
polymorphic cytochrome P450 2D6 isozyme
varies with genetics
does tramadol work well in cats?
yes- if can get into
what should you not give tramadol with?
tricyclic amines
serotonin reuptake inhibitors
monoamine oxidase inhibitors
do serotonin reuptake inhibitors work well for analgesia?
no- only potentiate one of pathways
how do tricyclic antidepressants work?
potentiate descending spinal inhibitory pathways by blocking presynaptic re-uptake of 5HT and NE
