opioid analgesis Flashcards
What is the purpose of opioid analgesics?
They are ____ because of their potential for ____?
To relieve moderate to severe pain
controlled substances, abuse
Opioid anagelsics exert their effects by binding to ____ that are located where?
Specific neuronal receptors located in the CNS
What is a narcotic?
When taken they have sleep inducing side effects and high doses can produce a state of unresponsiveness and stupor
What is the source of opioid analgesics?
The source of naturally occurring and semisynthetic narcotics?
Natural, synthetic, or semisynthetic sources
Opium poppy
Opium contains about how many biologically active compounds?including what?
20 compounds including morphine and codeine
What are the three families of endogenous opioids?
endorphins, enkephalins, and dynorphins
T/F do endogenous opioids exert their effects with he same receptor as exogenous opioids?
True
What are the the three receptor classes for opioid receptors?
Mu, Kappa, Delta
Stimulation of all three classes of opioid receptors causes…
However, which receptors are most important in mediating the analgesic effects of morphine?
Analgesia
Mu
What is the purpose of strong agonists?
Strong agonists have a high affinity for what receptor?
The most common member of this group is?
Strong agonists treat severe pain
Mu receptor in the CNS
Morphine
What is the purpose if mild to moderate agonists?
to treat moderate pain; do not have high efficacy as strong agoniosts
What are mixed agonist and antagonists?
How do these cause analglesia?
What are strength and weaknesses?
Exhbit some agonist and antagonist like activity at the same time
They bind to activate Kappa receptors and block or partially activate Mu receptors
Strengths- less risk of side effects of Mu receptors
Weaknesses- may produce psychotropic effects
- maximal analgesic effect may not be as strong as strong mu agonists
What is the purpose of the antagonist?
How is this achieved?
What are the primary agents uses as opioid antagonists?
Not produce analgesia but rather treat opioid overdoses and addiction
Displaces opioid agonists from the opioid receptors and block agonist effects
- Naloxone which reverses respiratory depression
- Naltrexone treats alcohol dependence
How can opioid analgesics be administered?
- oral
- parenterally, subcutaneous or intramuscular injection
- IV, epidural and intrathecal
- Transdermal patches
- Iontophoresis
Where are opioid receptors in the spinal cord concentrated and function?
On neurons in the dorsal horn; inhibit synapses responsible for transmitting nociceptive input to higher levels
Where can opioid drug (spinal effects) receptor interactions also take place?
What happens when these receptors are stimulated?
On the post synaptic membrane secondary afferent neuron
These receptors inhibit pain transmission by hyperpolarizing the postsynaptic neuron. making it less effective in relaying pain transmission because less NM is released
Where do opioids in the supraspinal brain affect?
Opioids affect the PAG in the midbrain to remove inhibition of descending efferent pathways
Where are opioid receptors located outside the CNS?
On the distal ends of primary afferent neurons
What type of administration should be used first for opioids?
Oral administration of mild to moderate opioid agonist
What is physical dependence?
Symptoms become evident within____ and peak on days ____ and _____; lasts about _____ days
The onset of withdrawal symptoms when the drug is abruptly removed
6-10 hrs; 2 and 3 days; lasts about 5 days
What are some problems and adverse effects of using opioids?
- mental slowing and drowsiness
- respiratory depression
-orthostatic hypotension
-GI distress: nausea, vomiting, and constipation
Why is Methadone of good use for those with opioid addiction?
Offers several advantages to patient such as milder withdrawal symptoms
This opioid-induced hyperalgesia is likely due to _____ in nociceptive pathways in susceptible patients.
increased activity of glutamate
