Opioid Analgesics Flashcards
What are the two categories or pain meds?
- Opioid analgesics
- Non-opioid analgesics
What are examples of Non-opioid Analgesics?
-acetaminophen
-aspirin
-ibuprofen
When are Opioid Analgesics usually taken?
After surgery and/or trauma, or those with chronic MSK pain and pain with advanced cancer
What are Opioid Analgesics?
A group of drugs that relieve moderate to severe pain by binding to specific neuron receptors located in the CNS and modifying synaptic activity
What is the original opioid analgesic prototype?
Morphine
What are Endogenous Opioids?
Opioids our body makes and releases to control pain and inflammation under certain conditions
Examples of Endogenous Opioids
-endorphins
-enkephalins
-dynorphins
What are the primary classes of opioid receptors?
- Mu
- Kappa
- Delta
Which opioid receptor is the most important for mediating the analgesic effects of many opioids?
Mu Receptors- located in the brain and spinal cord
Which opioid receptor has more significant side effects when stimulated?
Mu Receptors- respiratory depression and constipation, opioid abuse and addiction
What are Mixed agonists-antagonist opioids?
Drugs that stimulate kappa receptors while avoiding or blocking mu receptors in order to reduce side effects of respiratory distress or abuse
What are the different categories of Opioids?
-Strong agonists
-Mild to moderate agonists
- Mixed agonist-antagonists
-Antagonists
When are Strong Agonists used?
To treat severe pain and they primarily interact with Mu receptors
Examples of Strong Agonists
-Morphine
-Fentanyl
-Demerol
-Methadose
When are Mild to Moderate Agonists used?
Effective in treating moderate pain- do not have as high of an affinity or efficacy as strong agonists do
Examples of Mild to Moderate Agonists
-Codeine
-Hydrocodone
-Oxycodone
Why are Mixed Agonist-Antagonists beneficial?
They cause analgesia while producing less side effects, have a reduced risk of fatal overdose, and have fewer addictive qualities
Why are patients given Antagonist opioids?
These do NOT produce analgesia, but they block all opioid receptors and/or remove agonists from their receptors to treat overdoses and addiction
What is Naloxone?
Is an antagonist that can be given in emergency situations when a patient is in respiratory distress from an opioid overdose- will reverse respiratory depression within 1-2 mins
Pharmacokinetics of Opioids
-distributed in all body tissues
-main effect occurs after they reach the CNS
-metabolic inactivation takes place in the liver with a small amount occurring in the lungs, kidneys, and CNS
-excreted in the urine
Spinal Effects of Opioids
Acts at the SC to inhibit painful impulses from being sent from the periphery to the brain (afferent pathway)
Brain Effects of Opioids
Opioids bind to receptors in the brain and activate descending pain pathways (efferent pathways)
Peripheral Effects of Opioids
Opioids bind to the receptors find in the periphery by decreasing the excitability of sensory neurons while also inhibiting neurons from initiating transmission of painful stimuli toward the spinal cord
Which type of pain are opioids best at treating?
Moderate to severe pain that is constant in duration- not as effective on sharp, intermittent pain
Which type of opioid should be used first?
The oral administration of mild to moderate agonists- then the stronger agonists orally, then parenterally
Which drugs are used first for chronic pain?
Non-opioid drugs
Which drug route administration would be more effective in chronic, severe pain?
Parenteral routes- epidural or intrathecal space may be optimal
Oral Opioids are most effective when?
when given at regular intervals- patient should not wait until they feel pain because they need to keep their plasma levels at a therapeutic range
What are other uses of Opioids?
-used as an adjunct to general anesthesia
-cough suppressor (codeine)
-decrease GI motility to control severe diarrhea
Side Effects of Opioids
-sedative properties: mental slowing and drowsiness
-euphoria
-respiratory depression: slowing of breathing rate
-GI distress: nausea and vomiting, constipation
What is the most serious side effect of Opioids?
respiratory depression
What is addiction?
When an individual repeatedly ingests the drug for mood-altering and pleasure- to get “high”
What is tolerance?
The need to progressively increase the dosage of the drug to achieve an therapeutic effect when the drug is used for prolonged periods
What does Physical Dependence look like?
An onset of withdrawal symptoms when the drug is abruptly removed
-body aches
-diarrhea
-fever
-goosebumps
-irritability
-shivering
-sweating
-tachycardia
-N & V
-weakness/fatigue
Duration of withdrawal symptoms
Can be evident 6-10 hours after the last dose of the drug and will last for 5 days
What is Opioid Induced Hyperalgesia?
When some patients fail to respond to opioids or they report increases pain when given the drugs- may be due to genetic factors
What is used to treat opioid addiction?
Methadone- it is substituted for the opioid that patient is addicted to and then is slowly withdrawn- it has milder withdrawal symptoms than other opioids
What is used to treat opioid addiction?
Methadone- it is substituted for the opioid that patient is addicted to and then is slowly withdrawn- it has milder withdrawal symptoms than other opioids
