Analgesics- Opioids Flashcards
_______________ are a group of mainly synthetic agents that act at opioid receptors to proceed analgesic and other effects
Opioid drugs
Naturally occurring drugs extracted from opium
Opiates
Analgesia and stupor bordering on general anesthesia
Narcosis
Analgesia and amnesic state produced by admin of a neuroleptic and narcotic
Neurleptanalgesia
What parts of the pain pathways do opioids have an effect on
Transduction
Modulation
Perception
What are the 3 types of opioid receptors
Mu (u)
Kappa (k)
Delta
What are the most common opioid receptors
Mu
What is the MOA of opioid agonists
Activation of Mu
Couples with G protein
Reduces neurotransmitter release by decreasing Ca influx
What are the main sites where opioid agonists inhibit neurotransmitter
Dorsal horn of spinal cord
What is the distribution of opioids?
Widely distributed
Can cross BBB and placenta
How are opioids metabolized?
Conjugation to glucuronic acid
Cats are deficient –> metabolize more slowly
What are the full opioid Mu receptor agonists?
Morphine Hydromorphone Oxymorphone Fentanyl Carfentanil/Etorphine
What is a risk of using opioids especially in dogs with IV use
Histamine release
Morphine > hydromorphone
What full Mu receptor agonsit is very potent and used in wildlife
Carfentanil/Etorphine
What is the partial opioid Mu receptor
Buprenorphine
-> semisynthetic partial u agonist
‘Ceiling effect’
How does the onset and duration of buprenorphine compare to morphine
Buprenorphine has slower onset and longer duration than morphine
What is a mixed opioid receptor agonist-antagonist
Butorphanol
K agonist and u antagonist
=> sedation with less analgesic effects
What drug can be used to partially reverse the dysphroic effects from a pure Mu agonist
Butorphanol
Butorphanol is better for use against (visceral/Somatic) pain?
Visceral
What effects do opioids have in the CNS?
Behavioral changes
- CNS depression in dog, monkey, and humans
- CNS stimulation in cat, horse, ruminant, and pig
Motor activity
- depressed in dog
- increased in horse
Thermoregulation
- hypothermia in dog, rabbit and monkey
- hyperthermia in CAT, ruminant and horse
*** hyperthermia in cat-> not due to fever; can become intolerant to opioid
What is the main effect of opioids on the respiratory system
Dose dependent respiratory depression -> hypoventilation
What is the main effect of opioids on the cardiovascular system?
Minimal CV effects
Centrally medicated bradycardia and hypotension due to vasodilation ** most important in dogs
What are the main GI effects of opioids
Nausea, salivation, vomiting, and regurgitation
-Apomorphine ->emetic of choice in dog, TOXIC to cat
Ileum and Constipation
-increased intestinal wall tone, decreased propulsive motility
What are the clinical uses of opioid agonists
Analgesia
Sedation
Pre-anesthetic
Antitussive (anti cough)- non full u agonist (butorphanol)
Emetic (apomorphine)
Antidiarrheal
When should a full/pure opioid antagonists be used?
Overdose Toxicity Severe opioid-induced respiratory depression Prolonged anesthetic recover Cardiac arrest Cardiorespiratory arrest
What is a full u receptor antagonist
Naloxone
Naltrexone and diprenorphine
Methylanltrexone
Reverse opioid adverse effects and analgesic
What weak opioid u agonist also inhibits serotonin and NE reuptake
Tramadol
Generally used for short term post-op pain management
What semisynthetic opioid is used orally and an antitussive?
Hydrocodone
What is the emetic of choice in dogs but is toxic to cats
Apomorphine
What opioid has the most potent anti-diarrheal effects
Loperamide
What are precautions for opioid use?
Pre-existing ileus
Conditions causing increase ICP
Advanced or severe cardiac or hypoventilation
Acute renal failure/injury
History of opioid intolerance/hypersensitivity
Which of the following drugs MOA is described as having a 'ceiling effect' A. Morphine B. Naloxone C. Buprenorphine D. Butorphanol
C. Buprenorphine
T/F: hyperthermia can be induced by opioids in cats?
T
_____________ release is an important adverse effect to using morphine
Histamine
T/F: Butorphanol has stronger antitussive effects than buprenorphine
T
T/F: ileus is caused by decreased segmental intestinal motility
F
Increased GI segmental motility
Decreased GI propulsive motility
What is the drug of choice to completely reverse /antagonized the effects of fentanyl
Naloxone
