Opioid Agonist-Antagonists & Antagonists (Exam II) Flashcards
What is the primary indication for opioid agonist-antagonists?
- Used if unable to tolerate full agonist
Name the four advantages of opioid agonist-antagonists.
- Analgesia
- Less respiratory depression
- Low dependence potential
- Ceiling effect (prevents ODing)
How potent is Pentazocine?
- 1/5 as potent as morphine
What receptors does pentazocine bind to?
What type of activity does it exhibit?
- κ & δ receptor partial agonist activity
How is pentazocine excreted?
- Glucuronide conjugates in the urine.
Which opioid agonist-antagonist crosses the placental barrier causing fetal depression?
Pentazocine
What is the chronic pain dose of Pentazocine?
What dose and route would be equivalent to morphine 10mg?
- 10 - 30mg IV or 50 mg PO
- 20-30mg IM = 10mg morphine
Where is butorphanol excreted?
Bile
What receptors does butorphanol bind to?
- κ = analgesia & anti-shivering
- μ (low)
- σ (low)
Sigma (σ) receptors are associated with what side effect?
Dysphoria
2 to 3 mg of butorphanol is equivalent to _____ mg of morphine.
10
By what route is butorphanol rapidly and completely absorbed?
Intramuscular
What drug is an excellent choice for cardiac catheterization patients?
Why?
- Nalbuphine
- No increase in BP, pBP, HR.
What receptors does nalbuphine bind to?
How potent is it?
- μ receptor agonist that is equipotent to morphine.
Which agonist-antagonist has 50 times greater μ receptor affinity than morphine?
Buprenorphine
What is buprenorphine’s onset?
Duration?
- 30min onset
- 8 hour duration
What is buprenorphine’s greatest use?
- Opioid use disorder (has low risk of abuse)
Which two drugs have resistance to naloxone?
- Buprenorphine and Bremazocine.
Which opioid has high incidence of dysphoria and is therefore not utilized clinically?
Nalorphine
Which drugs are pure μ-opioid receptor antagonists?
- Naloxone
- Naltrexone
- Nalmefene
What receptors is naloxone effective on?
- μ, κ, δ (non-selective)
What non-opioid uses does naloxone have?
- ↑ contractility for shock
- Antagonism of general anesthesia at high doses.
What is the naloxone IV push dose?
Continuous infusion?
- 1-4 mcg/kg IV
- 5 mcg/kg IV infusion
What dose of naloxone is use for shock?
- > 1mg/kg IV
How long does Naloxone last?
- 30 - 45 minutes
Often needs redosing for overdoses.
What are the possible side-effects of naloxone?
- Analgesia reversal
- N/V
- ↑ SNS ( ↑ HR, BP, dysrhythmias, etc.)
What use does naltrexone have?
How long does it last and how is it adminstered?
- EtOH
- Given PO (more effective) lasts for 24 hours.
How does nalmefene’s potency compare to naloxone?
What is it’s dose and max?
- Nalmefene = naloxone
- 15 - 25 mcg IV (max of 1 mcg/kg)
What is methylnaltrexone’s use?
- Anti-emetic (antagonizes N/V from opioids)
What is Alvimopan and what is it used for?
How is it metabolized?
Why can’t it be used long term?
- μ-selective PO peripheral opioid antagonist for post-op ileus.
- Gut flora metabolism
- CV problems long term
What are the abuse-resistant opioid formulations?
- Suboxone (buprenorphine + naloxone)
- Embeda (long-release morphine + naltrexone)
- OxyNal (oxycodone + naltrexone)
What opioids-agonists have a significant effect on volatile anesthetics?
What do they do?
- Fentanyl & it’s derivatives decrease the MAC of volatiles by 50% or greater.
Fentanyl 3 μg/kg IV 25-30 min prior to incision will have what effect on which volatile gasses?
- 50% MAC reduction for isoflurane and desflurane.
Which opioid partial agonists have an effect on MAC?
- Pentazocine
- Butorphanol
- Nalbuphine
Where are receptors targeted with opioid neuraxial anesthesia?
- Opioid receptors of the substantia gelatinosa.
What is general rule of dosing for epidural opioids?
- Dose = 5 - 10 x normal
Diffusion of opioids across the _____ ______ results in systemic absorption.
dura mater
Where can opioids be injected during an epidural that results in systemic absorption?
What should be done if this occurs?
- Epidural venous plexus
- Add epi to the infusion.
What is Cephalad movement (in regards to epidurals)?
Cephalad Movement = the movement of drug/injectate up the spinal cord towards the brain.
What drug attribute decreases cephalad movement?
- Lipid solubility
________ exhibits much more cephalad movement than __________.
Why is this?
- Morphine ; fentanyl
- Fentanyl and it’s derivatives are much more lipid soluble and thus exhibit less cephalad movement.
What can cause cephalad movement? (besides characteristics of drugs themselves)
Coughing and/or straining
When would epidural CSF levels peak for the following drugs:
- Fentanyl
- Sufentanil
- Morphine
- Fentanyl - 20min
- Sufentanil - 6min
- Morphine - 1-4 hours
When would epidural administered plasma levels peak for the following drugs:
- Fentanyl
- Sufentanil
- Morphine
- Fentanyl - 5-10 min
- Sufentanil - 5 min or less
- Morphine - 10 - 15 min
When would epidural administered intrathecal/cervical CSF levels peak for the following drugs:
- Fentanyl
- Sufentanil
- Morphine
- Fentanyl - N/A
- Sufentanil - N/A
- Morphine - 1 - 5 hours (due to cephalad movement)
What is the most common side effect from neuraxial opioid administration?
Why does this occur?
- Pruritis
- Cephalad migration to trigeminal nucleus
What are the treatments for pruritis induced by neuraxial opioids?
- 10mg Propofol
- Naloxone
- Antihistamines
- Gabapentin
Name the list (its a lot) of side effects that can occur with neuraxial opioid administration.
- Pruritis
- N/V
- Urinary retention
- Respiratory depression
- Sedation
- Skeletal muscle rigidity
- Herpes virus reactivation
- Neonatal effects.
If neuraxial opioids induced a reemergence of a herpes virus, how long would this occur after opioid administration?
- 2 - 5 days
What sign would indicate respiratory depression from neuraxial opioid administration?
What is the treatment?
- ↓LOC from ↑CO₂
- Naloxone 0.25 μg/kg/hr IV
