Opiates, antagonists, and applications Flashcards
What are the two types of opiates?
Endogenous
Plant or synthetic: act at receptors for endogenous opiods
What are opioids?
Alkaloids from the exudate of seed capsules of the poppy plant
Define narcosis:
reversible CNS depression with stupor or insensibility produced by drugs
Define neuroleptanalgesia and what two drugs can be used to accomplish this
Sedation plus hypnosis
Opioid + tranquilizer
What are the four different receptors of opioids? Which is the most important?
Mu receptor**
Delta receptor
Kappa receptor
Sigma receptor
What effects does the Mu receptor control?
Analgesia and euphoria
Respiratory depression, inhibition of GI motility, and pupil effects
What effects does delta receptor have when activated?
Cardiovascular and respiratory depression
Analgesia at spinal level
What effects does the kappa receptor have?
Analgesia, primarily at spinal level
May be more beneficial for visceral pain
Sedation, dysphoria, psychomimetic effects
What are the effects of opiates on the CNS?
depression, sedation, and/or euphoria
Analgesia, may block cough, pain threshold is increased centrally
What are the effects of opiates on the respiratory tract?
Overall depression
Increases threshold for CO2, bronchoconstriction in dog
What are the effects of opiates on CV system?
vasodilation, bradycardia, drop in blood pressure
When would use of opiates be contraindicated?
Patient with hypotension
What are the effects of opiates on muscle?
Stimulation/rigidity
What are the effects of opiates on renal?
Increased ADH = increased H2O reabsorption
What are the effects of opiates on GI?
Reduced motility, secretions, and peristalsis
Increase tone of smooth muscle and may see emesis in some animals
What are the effects of opiates on the behavior of dogs? cats? cattle?
Depression in dogs and monkeys
Excitation in everything else (cats, horse, goat, sheep, pig, and cattle)
What are the effects of opiates on thermoregulation? What species does it often raise the body temp most in?
Increase: CATS
Hypothermic in some: rabbits, dogs, and monkeys
What are the ways opiates are eliminated from the body? What form is it in?
Glomerular filtration or bile
In the GLucuronide form (this is also the more potent form)
Describe the different categories of DEA controlled drugs:
Schedule 1: no currently accepted medical use
Schedule 2: high potential for abuse. Must be ordered on special form
Schedule 3, 4, and 5: only require a DEA number
What receptors does Apomorphine act on? What is it very good at?
Acts on dopamine receptors
Ecellent inducer of emesis in dogs
T/F Apomorphine should not be used by itself for narcosis
TRUE; does not do this well on its own
T/F most synthetic opiates are mu or kappa agonists making them good for analgesia
TRUE
What is a benefit of Hydromorphine when compared to morphone?
Less nausea, emesis, or GI effects
What are some benefits of using Buprenorphine over morphine?
Longer acting, less GI or respiratory effects
What species are more susceptible to excitement from opiates?
Cats and horses
What species is the half-life of opiates longer/
Cats; decreased biotransformation in liver
What species is more susceptible to emesis with opiate use?
Dogs
What are some uses for opiates in the veterinary setting?
Pain management Pre-anesthetic Neuroleptanalgesia (Short duration) Chemical restraint/sedation Emesis Treatment of diarrhea
What are some situations that would would not consider using opioids?
Shock (increases hypotension) Convulsive disorders (enhances seizures) Head injury (increases IC pressure) Uremia Toxemia (Impaired excretion of urine) Liver failure Young animals (Decreased biotransformation) Strychnine
T/F Opioid antagonists are very fast acting
TRUe
T/F Opioid antagonists can reverse hypotension in shock
TRUE
Why would you not want to use opioid antagonists to reverse hypotension in shock?
They also block mu receptors for analgesia
What are the most common opioid antagonists used?
Naloxone and naltrexone
What is re-narcotization?
Major concern with potent opioids
Involves giving an antagonist that is shorter acting than the opioid agonist
