Opiods Flashcards
Pain
Unpleasant sensory and emotional experience with actual or potential tissue damage
Nociceptors (pain receptors)
Free nerve ending with cells bodies outside the SC —> certain threshold reached before signal triggered —> threshold reached and signal passes along axon into the SC
What sense pain/ primary target of opioids!
Dorsal root ganglion
Opioid receptors and natural pain chemicals
Mu (MOP) receptors- endorphins
Kappa (KOP)- dynorphin
Delta (DOP)- encephalin
Opioid receptor locations
MOP and KOP- brain, SC and peripheral sensory neurons
DOP- brain and peripheral sensory neurons
Major effect of opioids receptors
Analgesia (spinal and supraspinal)
MOP effects
Respiratory depression
Decreased GI motility, biliary secretions, urine voiding reflex, uterine contractions
Increased appetite
Euphoria
Antidiuresis
Miosis/ mydriasis
Nausea/ vomiting
Immunimodulation
KOP receptor major effects
Decreased GI motility
Increased appetite
Sedation
Diuresis (increased ADH release)
Miosis / mydriasis
DOP receptor major effects
Increased appetite
Immunomodulation
Opioids MOA
Opioids bind to spinal and supraspinal receptors —> inhibit adenylyl cyclase (decrease CAMP) —> activation of K+ ion channels and hyperpolarization —> inhibits excitatory NT release
Opioid therapeutic uses
Analgesia
Sedation
Calming and euphoria
Diarrhea, decreased GI motility
Induction and maintenance of anesthesia
Agonist opioids
Morphine
Methadone
Hydromorphone
Fentanyl
Tramadol
Mixed agonist/ antagonist opioids
Butorphanol
Buprenorphine
Antagonist/ reversal of opioids
Naloxone
Morphine PE
Analgesia, emetics , miosis, decreased GI motility
Morphine therapeutic uses
Acute pain, anesthetic premedication, antitussive
Adverse effects of morphine
Hyperexcitability, hypotension, cerebral hemorrhage or edema
Anaphyloid rx (mast cell degranulation)
Methadone
Synthetic OPIOD
Slower elimination than morphine
Methadone therapeutic uses
Preanesthetic, algesia
Methadone adverse effects
Sedation, vomiting, constipation, respiratory depression
Hydromorphone
5x analgesia potency of morphine
Replaced oxymorphone
Hydromorphone therapeutic uses
Analgesia, preanesthetic and anesthetic
Hydromorphone adverse effects
Panting (cool down) and bradycardia, dose dependent excitement, cerebral hemorrhage or edema
Fentanyl PK
More rapid onset than morphine but shorter duration
75-125 x more potent
How do you measure fentanyl?
MICROGRAMS!!
Fentanyl therapeutic uses
Analgesia (continuous infusion), anesthetic induction in dogS
Neuroletanalgesia
Adverse affects of fentanyl
Motor response
Panting, defecation, flatulence, bradycardia, salivation
Tramadol
Synthetic analog of codeine
MOP agonist (weak) and inhibits serotonin and NE uptake @ synapse
Tramadol PK
Active metabolite is desmethyltramadol
Tramadol therapeutic affects
Analgesic, antitussive in dogs and cats
Butorphanol
Agonist-Antagonist
High affinity for MOP receptors but not activity (antagonist)
High affinity for KOP receptors
Butorphanol therapeutic uses
Opiod reversal (antagonist), analgesic, antitussive
short duration of efficacy limits its use as a primary
Buprenorphine
Most generally useful analgesic in dogs and cats (30x potency of morphine)
Longer duration of action than other opiods
Buprenorphine MOA
High affinity for MOP but only partial agonist
KOP antagonist
Buprenorphine therapeutic uses
Analgesia for mild to moderate pain in small animals (buccal/ transmucosal admin in cats)
Simbadol for Cats
Buprenorphine long acting SQ
Slow release SQ prep
Offers 24 hour surgical pain control for cats (1x/day)
Zorbium for Cats
Buprenorphine Transdermal
First FDA approved long acting transdermal for bupren for cats
4 days, single dose
Naloxone
Pure opiate antagonist
High affinity for MOP receptors
High doses will reverse DOP and KOP
Naloxone PK
Duration of action less than agonists
Repeated administration for opioid reversal (monitor and redose)
Naloxone therapeutic uses
Reversal of opioid induced respiratory depression
Treat shocks (IV and IM, nasal)
Extralabel use in dogs and cats
Adverse effects of naloxone
CNS sedation
Respiratory and cardiac depression
Naloxone contraindicated
Shock
Severe cranial trauma and diseases associated with respiratory compromise
Continuous opioid use
If given longer than 5-7 days they’ll get withdrawal signs (nausea, aggregation, vocalization, vomting, hyperactivity) after discontinuing the drug or antagonist administered
Opioid scheduling
Morphine and other pure: 2
Bupren: 3
Buto: 4
(2-5, low potential of abuse)
