Opioid Agonist/Antagonist Flashcards
What is the name of the fibers that send a fast signal of sharp, well localized pain?
A delta fibers
What is the name of the fibers that send a slow signal of dull, poorly localized pain?
C fibers
A pain signal travels up 3 neurons to make the ______ tract
spinothalmic
The first order neuron is from the ____ to the _____.
Periphery to the dorsal horn.
The second order neuron is from the ____ to the _____.
dorsal horn to the thalamus
The third order neuron is from the ____ to the _____.
thalamus to the cerebral cortex
What is transduction?
The tissue is injured and chemicals are released that causes activation of peripheral nerves and immune cells. The chemicals are transduced into an action potential by nerves and then interpreted by the brain
What is transmission?
The signal from transduction is the electrically relayed up the spinothalmic tract to the brain
What is modulation?
The inhibition of signals down the decending pathyway from the release of GABA and glycine in the brain/spinal cord and norepinephrine, 5-HT (serotonin), and endorphins. Regulates the amount of pain we feel.
What is the most important site for pain modulation?
substantia gelatinosa
What is perception?
The processing of the signals in the cerebral cortex and limbic system. Subjective to each person. Can be influenced by many factors.
What are the 3 types of opioid analgesic chemical classes?
Phenanthrenes, phenylpiperidines, phenylhepatones
What are 3 meds that are phenanthrenes (an opium class)
Morphine, Codeine, Thebaine
What are 2 meds that are benzylisoquinolines? (an opium class that lacks opioid activity?
papavarine, noscapine
What is the name of the class of synthetic opioids?
Phenylpiperidine derivatives
What medications are phenylpiperidine derivatives? (5)
meperidine fentanyl sufentanil alfentanil remifentanil
What are 3 types of endogenous substances that act as natural pain killers?
Endorphins
Enkephlins
Dynorphins
What substances are released in response to tissue injury?
COX-2 and prostaglandins
Which ion decreases after an opioid binds to a receptor? Which one increases?
Ca++ movement inward decreases, K+ outward movement increases
What effect does the movement of potassium have to an opioid receptor
It hyperpolarizes the post-synaptic neuron, the trigger potential moves further away from the resting membrane potential, makes it more resistant to stimulation.
What are the 3 types of opioid receptors?
Mu, delta, kappa
What are the side effects of activating the Mu receptors?
euphoria, miosis, hypothermia, bradycardia, urinary retention, pruritis, hypoventilation, physical dependence, constipation
What are the cardiovascular side effects of opioids?
Minimal effect in healthy patients, bradycardia, dose dependent vasodilation
Morphine and Demerol-histamine release
What are the ventilation effects of opioids?
decreased rate, prolonged inspiration and delayed expiration, increased CO2, decreased response to rising CO2, decreased minute ventilation
What are the symptoms of Serotonin Syndrome?
Sweating, tachycardia, agitation, hypertension, clonus, diarrhea, tremor, hyperrflexia
What is hyperalgesia?
a decrease in pain threshold in an area of inflammation. Low stimuli causes pain.
Place in order from most to least potency:
Alfentanil Remifentanil Sufentanil Fentanyl Hydromorphone Demerol Morphine
Sufentanil>Fentany=Remifentanyl>Alfentanil>Hydromorphone>Morphine>Meperidine
What is a critical side effect of Morphine?
Histamine release
What is the active metabolite of Morphine?
moprhine-6 glucuronide
Elimination of morphine may be impaired in patients with _____. This can cause an accumulation of active metabolites and cause _______.
Renal disease, respiratory depression
Which opioid is least potent?
Demerol
What is Demerol used for in the PACU?
Post-op shivering
Is Demerol mostly ionized or unionized?
Ionized (93%)
Demerol and MAOI’s or SSRI’s can cause _____.
Serotonin Syndrome
What are some side effects of Demerol?
Tachycardia, decreased contractility, orthostatic hypotension, histamine release, delirium and seizures with prolonged use
Demerol is 90% metabolized by the _____ enzyme
CYP450
The active metabolite of Demerol is_____.
Normeperidine
Fentanyl: Onset: DOA: Half-life Ionized or nonionized?
Onset: 2-5 min
DOA: 30min-1hr
Half-life: 2-4 hrs
Highly Ionized
What are side effects of Fentanyl?
Respiratory depression, bradycardia, decreased SVR, muscle rigidity
Sufentanyl:
Onset:
DOA:
Half-life:
Onset: 1-3 min
DOA: dose dependent
Half-life: 6hrs
What are some side effects of Sufentanyl?
Significant bradycardia-can cause decreased cardiac output and then decreased blood pressure
What are two benefits of Sufentanyl?
Decreased cerebral metabolic O2 demand, longer period of analgesia with less respiratory depression
Alfentanil:
Onset:
DOA:
Half-life:
Onset: Immediate
DOA: brief, rapid redistribution
Half-life: 1.5hrs
What are side effects of Alfentanil?
Bradycardia and hypotension
What makes Alfentanil work so quickly?
The pka is a base (6.4) It is non-ionized, then when added to the circulation, you get more non-ionized portion of the drug.
How is Alfentanil metabolized?
CYP450
Remifentanil:
Onset:
DOA:
Half-life:
Onset: 1 min
DOA: 5-10 min
Half-life: not listed
How is Remifentanil broken down?
hydrolysis by plasma esterases
What are side effects of Remifentanil?
Muscle rigidity, hypotension, hyperalgesia
What does Remifentanil do to the MAC and propofol needs?
Reduces it by 50%
How do you calculate a dose of Remifentanil for an obese person?
use ideal body weight plus 25%
How much should you reduce a Remifentanil dose by for the elderly?
50-70% reduction
Hydromorphone (Dilaudid)
Onset:
DOA:
Half-life:
Onset: 15-30min
DOA: 4-5hr
Half-life: 1-3hr
Oxymorphone is a result of an addition of a ______ group to hydromorphone
Hydroxyl
About _____% of Codeine is metabolized or changed to _____ in the liver.
10%, morphine
What is a side effect of Codeine?
constipation
What is a use for Methadone?
Suppression of withdrawal symptoms in a physically dependent person
Methadone is a ____ receptor AGONIST and a _____ receptor ANTAGONIST
Mu, NMDA
Methadone can increase the ____ interval.
QT
What does Nubain do?
Reverses respiratory depression from Fentanyl but maintains analgesia
What are 3 opioid agonist/antagonists?
Nalbuphine (Nubain), Butorphanol (Stadol), Buprenorphine (Tawin)
What do opioid antagonists do?
Take away all analgesia on board
What are 2 opioid antagonists?
Naloxone and Naltrexone