Opioids Flashcards
Morphine
Mu agonist
- mod-severe pain
- pre med, sedative & analgesic (visceral & somatic pain)
Onset: 5-10 mins
Duration: 30 mins - 3 hrs
Controlled!
Routes: IM or IV (SQ, oral, rectal, transdermal, epidural routes, CRI)
CAUTION: rapid iv injection = histamine release (puts patient into shock)
Morphine adverse effects
Resp depression ðŦ
Hypoventilation, panting
Sedation ðĪ
Nausea & Vomiting ðĪŪ
Constipation
Increases temp in cats - decreases temp in dogs
Miosis (dogs) and mydriasis (cats)
CAUTION: rapid iv injection = histamine release (puts patient into shock)
Causing - hypotension & reflex tachycardia
Colic in horses ðī
Excitement or dysphoria in cats & horses
Hydromorhone
Mu agonist
Mod-severe pain
Controlled!
Premed & analgesic
5x more potent than morphine
Onset: 5-10 mins
Duration: 2-6 hrs
Hydromorphone side effects
Vomiting & panting
Nausea
Hypoventilation
Resp depression
Sedation
Constipation
Hyperthermia in cats ð
Similar effects to morphine but no histamine release & less potential to cause excitement
Fentanyl
mu agonist
Mod-severe pain
MOST POTENT (100x more than morphine)
Onset: 1-2 mins
Duration: 20 mins
Pre med & analgesic (visceral & somatic)
Profound sedation
Routes: IV, CRI & transdermal patch
Controlled drug
Fentanyl adverse effects
Resp depression
Panting
Bradycardia
Vomiting
Analgesia (visceral and somatic)
Sedation
Hypoventilation
Constipation
Hyper-responsive to sound
Increases temp in cats ð
What parts of the pain pathway do pure mu agonists affect?
Pure mu agonists affect:
Transduction
Modulation
Perception ð§
Methadone
Mu agonist & NMDA antagonist
Onset: 2-5 mins IV, 20-30 mins IM
Duration: 4-6 hrs
What are the pros of methadone?
Little effect on cardio/Resp system
No vomiting or panting
Buprenorphine
Partial mu agonist
Mild- mod pain
Controlled drug
Premed & analgesic (mild-mod visceral & somatic)
Onset: 30 min
Duration: 6-8 hrs (can be extended w different combos)
Routes: orally, IV, IM, SQ, epidural
Partial reversal for pure mu
Cons of Buprenorphine
Little sedative effect on its own
Poorly reversible
Increases temp in cats
Resp depression difficult to reverse, esp high doses
Buprenorphine (partial mu) mode of action ( pain pathways )
Very weak kappa antagonist
Transduction
Modulation
Perception
Butorphanol
Kappa agonist - mu antagonist
Premed & analgesic (mild-mod visceral)
IV, IM, SQ, CRI
Controlled drug
Onset: 5-10 mins
Duration: 1 hr
Can use as partial reversal for pure mu
Adverse effects of Butorphanol
Excitement in horses & cats
Sedation
Nausea
Dysphoria
Mild Resp depression
What is Butorphanol good for?
Patients w no pain & minimally painful procedures
Less sedation, dysphoria and Resp/cardio depression then most opioids
Min CV effects: vaguely induced bradycardia
General facts of opioids
Controlled drugs
Reversible
Higher doses = greater sedation & longer duration BUT increases side effects
Can be used alone or combined w alpha 2s, NSAIDs or local anesthetics for greater pain
General adverse effects of opioids
CNS depression- increase excitement (cats) , sedation
Can increase IOP/ICP (therefore contraindicated for head trauma)
Cardio/resp - bradycardia (vagal nerve stimulation), dose dependant, min Resp depression, panting (bradycephalics)
Nausea & vomiting
GI stasis/ ileus
Mode of action of kappa agonists
Stimulates kappa receptors and blocks mu receptors
Transduction
Modulation
Perception
Reversal of opioids
Naloxone
Onset: 2 mins IV, 5 mins IM
Duration: 30-60 mins
Neuroleptanalgesia
Opioid analgesic with tranquilizer or sedative
To increase pain relief & calm patient
Emergence delirium
Inadequate sedation
Causing confusion & stress (vocal on recovery, appearing painful)
Must administer additional opioid to help them settle or alpha 2 for dysphoria
At which levels of the pain pathways do opioids act on
Transduction
Modulation ðĪŠ
Perception ð§
Are opioids analgesic
Yes, they act by binding to the receptors in the CNS to block pain!
