Opioids and Opioid Antangonists Flashcards
What is a natural opioid and give example
Naturally derived from opium
morphine
What is a synthetic opioid and give example
Manufactured by synthesis
fentanyl
What is a semisynthetic opioid and give example
Chemical modification of morphine
herioin
What type of receptors do opioids bind?
G coupled protein receptors
Where in the body do opioids bind to receptors?
brain and spinal cord
What are the endogenous opioid ligands?
Enkephalins
Endorpins
Dynorphins
How do opioids affect neurotransmitter release?
decrease
in the brain and spinal cord, where are opioid receptors?
Periaqueductal gray matter amygdala Corpus striatum Hypothalamus Spinal cord (substantia gelatinosa)
where is the mu1 receptor located?
supraspinal and spinal
What are the effects of the Mu1 receeptor?
Analgesia--main action Euphoria N/V, Pruritis Low abuse potential Bradycardia
What binds to the Mu1 receptor?
Endorphins, morphine and sythetic opioids
Where is the Mu2 receptor?
spinal
What are the effects of the Mu2 receptor?
Hypoventilation analgesia Euphoria, Sedation Physical dependence Constipation
What binds to MU2 receptor?
Endorphins, morphine and sythetic opioids?
Where is the kappa receptor?
Supraspinal, spinal
What are the effects of the kappa receptor?
Analgesia
Respiratory depression
Dysphoria
diuresis
What binds to the kappa receptor?
Dynorphins
Agonist-antagonist principally
Nalbuphine
How is the kappa receptor in relation to high intensity pain?
resistant
Where are the delta opioid receptors?
supraspinal, spinal
What are the effects of the delta receptor?
Analgesia
Respiratory depression
Physical dependence
Urinary retention
What binds to delta receptors?
enkaphalins
Which receptors cause respiratory depression?
Mu2, Kappa, and delta
Which receptor would give you the feeling “I feel like I am going to die”?
Kappa
which receptor is associated with constipation?
Mu2
Which receptors are associated with physical dependence?
Mu2 and Delta
kappa has low abuse potential
what are the 4 classic side effects of neuraxial opioids?
Pruritis
N/V
Urinary retention
Ventilatory depression
Are neuraxial opioid specific or somatic or visceral pain?
visceral
What are the cardiovascular effects of most opioids?
What is the exception?
decrease sympathetic tone and therefore decrease BP, HR. There are minimal effects on the contractility
Merperidine is the exception, it has anti muscarinic effects
How do opioids affect RR, Vt, MV, and PaCO2?
Decrease RR, INcrease Vt, but overall decreases MV, and thus increases PaCO2
What effect do opioids have on cough?
supress
What effects do opioids have on MAC?
reduce
What effects do opioids have on cerebral blood flow, metabolic rate and ICP?
Decrease CBF and CMRO2
ICP increases due to increase PaCO2 from hypoventilation
Which opioid may cause siezures?
Merperidine, from accumulation of normerperidine
What is biliary colic?
Spasm of the sphincter of Oddi
Feels similar to angina
If not relieved by NTG then it is biliary colic
What can you give to relieve pain associated with biliary colic?
nalaxone
How do you reverse biliary colic?
Glucagon 2mg IV
What are the GI side effects of Opioids?
N/V
constipation
delayed gastric emptying
biliary colic
Whar are the GU side effects of opioids?
Urinary retention due to increase in tone of ureter and vesicle sphincter
Which two opioids cause the most histamine release?
morphine and merperidine
what opioid side effect is associated with the Erdinger-Westphal nucleus?
Miosis–oculomotor nerve
What side effect of opioids is associated with difficulty to bag mask pt?
truncal rigidity
Which two effects of opioids aren’t subject to tolerance?
Constipation and miosis
What are the triad of symptoms for an opioid overdose?
Miosis
Respiratory depression
Coma
What is the onset of morphine?
15-30 min onset with peak effect at 45-90 min
What is the peak effect of morphine?
45-90 min
What is the duration of morphine?
3-4 hours
How is morphine metabolized? What is the metabolite and how does it compare to morphine?
Metabolized via conjugation with glucuronic acid in liver and in kidney.
Its metabolite is morphine-6-gucuronide, which is more potent than morphine
What is the dose for intraoperative analgesia of morphine?
.1/-1mg/kg
How does merperidine compare to morphine?
0.1 potency
How can merperidine be delivered?
IV, IM or PO?
How can morphine be delivered?
IV, IM
Wha tis the peak effect and duration time for merperidine?
Peak: 5-7 min
Duration: 2-4 hours
How does merperidine behave like atropine/local?
blocks sodium channel
causes tachycardia, dry mouth, mydriasis
How is merperidine metabolized?
90% hepatic metabolism to normeperidine, which is renally eliminated
What is the dose of merperidine for post-op shivering?
12.5-25mg–1 time dose
how does fentanyl compare to morphine?
75-125 times more potent
Waht is the peak ffect and duration of fentanyl?
peak: 3-5 minutes
duration 30-60 min
how can fentanyl be administered?
IV, transdermal, PO, intranasal
Fentanyl is _____ soluble and protein bound
lipid
Where is the first pass uptake of fentanyl?
lungs–up to 75%
HOw does sufentanil compare to fentanyl?
5-10x as potent with greater affinity for opioid receptor
what is the peak and duration of sufentanil?
Peak 3-5 minutes, duration 30-60 minutes
What is the dose for DL of sufentanil?
0.3-1mcg/kg 1-3 minutes before DL
What is the infusion rate for sufentanil?
0.5 mcg/kg followed by 0.5 mcg/kg/hr
How does alfentanyl compare to fentanyl?
1/10-1/5 as potent
What is the duration and peak of alfentanyl?
Peak 1.5-2 minutes
Duration 10-20
HOw does renal failure affect Alfentanyl?
does not alter clearance
What are the uses for alfentanyl?
Because of its rapid on and off of intense analgesia, it is good for retrobulbar block or DL
What is the dose for alfentanyl?
5-10 mcg/kg
How does remifentanyl compare to fentanyl?
similar potency
What is the peak effect and duration of remifentanyl?
peak 1.5-2 minutes
Duration 6-12 minutes
How is remifentanyl metabolized?
plasma and tissue esterases
How can remifentanyl be used?
RBB, continuous drip; quick recovery cases
What is the dose and drip rate for remifantanyl for DL?
0.5-1mcg/kg, then 0.25-0.5 mcg/kg/min
What are the uses of codeine?
antitussive
analgesia for mild to moderate pain
What are the uses for methadone?
long term relief of chronic pain and opioid withdrawl
How does dilaudid compare to morphine?
8x as potent but shorter acting
What type of drugs are Pantozocine, butorphanol and nalbuphine? What are the advantage?
Partial agonist and/or competitive antagonist at opioid receptors
Produce analgesia with limited respiratory depression, but do have a ceiling effect
Name two opioid antagonists and routes of administration.
Nalaxone-IV
Naltrexone-po
Which opioid receptors does nalaxone antagonize?
pure Mu antagonist
What is the duration of nalaxone?
30-45 minutes
What is the dose of nalaxone?
1-4mcg/kg
Dilute 400mcg vial in 100 and give 1-2 cc over 2-3 minutes
What are the side effects of nalaxone?
N/V
Pain
tachycardia
Increased SNS activity
