Opioid Analgesics Flashcards
What are examples of opioid analgesics?
morphine, oxycodone, remifentanil, hydrocodone, propoxyphene
Oxycodone is found in formulations like Oxy-Contin and Percocet (with acetaminophen). Hydrocodone is found in Vicodin (with acetaminophen). Propoxyphene in Darvocet (with acetaminophen).
What do pure opioid receptor agonists activate?
mu, delta, and kappa opioid receptors
They mimic the effects of endorphins, enkephalins, and dynorphins.
What types of pain are opioids used to treat?
moderate to severe pain; acute and chronic pain
Opioids are often prescribed for pain management.
What are some formulations of fentanyl?
patches, nasal sprays, tablets, lozenges, films
Fentanyl is a full opioid receptor agonist that is 100 times more potent than morphine.
What is the recommended duration for prescribing immediate-release opioids for acute pain?
three days or less
More than seven days will rarely be needed.
What are some pharmacotoxicological effects of opioids?
euphoria, respiratory arrest, N/V, miosis, constipation, convulsions
Opioids can stimulate the limbic system and suppress respiratory control.
What is Naloxegol used for?
treating constipation in patients on long-term opioid therapy
It is a mu opioid receptor antagonist that does not pass the blood-brain barrier.
What is the role of methadone in opioid addiction treatment?
reduces daily cycles of craving and withdrawal symptoms
Methadone is a long-acting opioid agonist useful for treating opioid dependence.
How does methadone help txt drug addiction?
While a full opioid receptor agonist,
bc its so long acting it blunts the reward pathway and blunts that drug seeking
What type of opioid receptor agonist is buprenorphine?
partial opioid receptor agonist
It is used in the treatment of moderate to severe opioid use disorder (OUD) and as an analgesic.
Fill in the blank: Opioid receptors include mu (μ), delta (δ), and _______.
kappa (κ)
Each subtype has different effects and anatomical distributions in the CNS.
What are the effects mediated by mu (μ) receptors?
analgesia, euphoria, physical dependence, sedation, bradycardia, respiratory depression
Different subtypes of opioid receptors mediate various responses.
True or False: Partial opioid agonists have the same risk for addiction as full agonists.
False
Partial agonists produce a smaller degree of effects and have a lower risk for addiction.
What is the purpose of opioid rotation in chronic pain management?
diff opioids bind to diff subtypes of opioid receptors with different affinities and biological consequences (e.g. down-regulation of receptors),
opioid rotation is a treatment strategy for chronic pain that is used to **balance analgesia with the risks for the development of tolerance and adverse side-effects. **
Example: switching oxycodone ER can be rotated to hydromorphone ER
What does the activation of presynaptic opioid receptors do?
inhibits N-type voltage-dependent calcium channels
This blocks exocytosis and the release of excitatory neurotransmitters.
What is the significance of the long half-life of methadone?
blunts the reward pathway and minimizes peaks and troughs of addiction
This helps in reducing cravings and withdrawal symptoms.
What is the classification of codeine?
moderate to strong opioid receptor agonist
Besides analgesia, codeine is also used as an antitussive medication.
What is the difference btwn mu 1 and mu 2 effects?
mu (u1) receptors induce analgesia, euphoria, and physical dependence;
mu (u2 ) receptors cause sedation, bradycardia and respiratory depression;
What so delta (δ) receptors mediate?
delta (δ) receptors mediate spinal anesthesia and the development of tolerance to opioids;
What do kappa (κ) receptors mediate?
kappa (κ) receptors mediate spinal anesthesia, miosis, and sedation.
Name an example of an opioid formulated with non-opioid medication.
Percocet – oxycodone/acetaminophen
Vicodin – hydrocodone/acetaminophen
(synergistic effects)
How do endorphins, enkephalins and dynorphins help with pain?
endorphins, enkephalins and dynorphins which suppress pain impulse transmission through “pain gates”
Describe full opioid binding for full effect.
pure agonists can bind to the receptor and cause a confromational change so close to what your endogenous endorphins etc can produce as a biological response when they bind
–> full activation of receptor
–> full signal transduction
–> maximal BR
Describe partial opioid binding for partial effect.
partial activation of pathway -> partial BR –> partial pain relief, but will lack as much risk for addiction and partial SE
can be called agonists/antagonist opioids bc they agonize for pain relief, but they antagonize the other part of this spectrum for SE and addiction behaviors
Why are partial opioid agonists are used to treat opioid addiction?
bc they work to avoid withdrawal symptoms that are the primary cause for relapse behaviors.
Level of WD sympt -> relapse
long HL+partial agonist actions prevents
Why is a return to abuse behaviors during partial opioid agonist therapy is less likely?
bc illegal opioids (e.g. heroin) do not create the same feelings of reward because the opioid receptors are already occupied by buprenorphine which is a partial agonist.
If the development of withdrawal symptoms triggers relapse behaviors, what about the med helps prevent WD symptoms?
long half-life and partial agonist actions of buprenorphine prevents these events
Describe pain gates.
Pain “gates” include inhibitory nerve terminals that converge at synaptic junctions between the first order and second order neurons that transmit
pain impulses to CNS.
Many inhibitory nerve terminals release natural opioid agonists that includes endorphins, enkephalins, and dynorphins.
What do many inhibitory nerve terminals release?
natural opioid agonists that includes endorphins, enkephalins, and dynorphins.
sub-types of opioid receptors include mu (μ); delta (δ ), and kappa (κ ) receptors that are located on presynaptic or postsynaptic membranes.
What do presynaptic opioid receptors activate?
presynaptic opioid receptors activate signal transduction pathways that inhibit the N-type voltage-dependent calcium channels which blocks exocytosis and the release of excitatory neurotransmitters
What do postsynaptic opioid receptors activate?
postsynaptic opioid receptors activate signal transduction pathways that open potassium channels which hyperpolarize membranes and block the formation of action potentials that are essential for transmitting pain sensations.
