Opioid Drugs Flashcards
What effects do opioids have on the CNS?
+ effects:
+sedation, narcosis
+pain relief of severe pain
- effects:
- anxiety, disorientation, dysphoria
- excitement and/or dysphoria (in cats, horses, and ruminants), so must be used at lower doses in these species
What effects do opioids have on the brain?
+ effects:
none
- effects:
- increase intracranial pressure (because of the increase in PaCO2)
- increased responsiveness to noise
- addiction
What effects do opioids have on the cardiovascular system?
+ effects:
None
- effects:
- bradycardia
- hypotension
What effects do opioids have on the respiratory system?
+ effects:
None
- effects:
- minimally depressed respiratory rate and tidal volume (which leads to decreased PaO2 and increased PaCO2)
What effects do opioids have on the eyes?
+ effects:
None
- effects:
- increased intraocular pressure (because of increased PaCO2 in blood)
- miosis (dogs) (excessive pupil constriction)
- mydriasis (cats, horses, ruminants) (pupil dilation)
What effects do opioids have on the thermoregulation of the body?
+ effects:
None
- effects:
- hypothermia (dogs)
- hyperthermia (cats)
- sweating (horses)
What effects do opioids have on the GI system?
+ effects:
None
- effects:
- initial GI stimulation (salivation, vomiting, diarrhea, flatulence), followed by GI stasis (contraindicated in horses (colic) and any animal with a GI obstruction)
What effects do opioids have on the urinary system?
+ effects:
None
- effects:
- decreased urine production and urine retention
Where does morphine fall on the scale of opioids?
- pure agonist opioid
- 1st opioid used, baseline to compare others to
When given by IV, should morphine be given slowly or quickly?
slowly
(giving too quickly can cause the release of histamines, which results in symptoms of decreased blood pressure, flushing, and pruritis)
Where does oxymorphone/hydromorphone/methadone fall on the scale of opioids?
- pure agonist
- more potent than morphine (greater analgesic potency, longer duration of analgesia, greater sedative effect)
- does not cause histamine release like morphine
- less likely to cause vomiting in cats and dogs than morphine (methadone is the least likely to cause vomiting)
hydromorphone: slightly less potent than oxymorphone and less likely to cause excitement in cats
While methadone is a pure opioid agonist, what does it antagonize?
NMDA receptors in the spinal cord (can help prevent wind-up)
Where does fentanyl fall on the scale of opioids?
- pure opioid agonist
- more potent than oxymorphone/hydromorphone
- with potent effects come potent side effects (profound sedation, bradycardia, respiratory depression)
Where does meperidine/pethidine fall on the scale of opioids?
- pure opioid agonist
- less potent than morphine
- given SC & IM only (IV can cause severe hypotension)
- may cause histamine release (like morphine)
- avoid using with MAOIs
Where do carfentanil/etorphine fall on the scale of opioids?
- pure opioid agonists
- more potent than fentanyl
- for use on zoo/wild animals (such as in blow darts)
- reversal agents are naltrexone and diprenorphine
