💊370.3: Pain Flashcards
What are examples of endogenous opioids?
- Enkephalins
- Endorphins
- Dynorphins
What are the 3 types of opioid receptors?
Mu»_space; kappa»_space; delta
Analgesics don’t bind to delta, only endogenous opioids
What are important effects of activations of mu receptors?
- Analgesia
- Resp depression
- Sedation
- Sedation
- Euphoria
- Physical dependence
- Decreased GI motility
What are important effects of activations of Kappa receptors?
- Analgesia
- Sedation
- Decreased GI motility
What are prototypes of pure opioid agonists?
Morphine (strong)
Codeine (moderate to strong)
What is a prototype of opioid agonist-antagonists (partial agonists)?
Pentazocine (Talwin)
What is a prototype of a pure opioid antagonist?
Naloxone (Narcan)
What is the mechanism of action of morphine?
- Binds to CNS receptors, peripheral nerve terminals, and cells in GI tract
- Occupied opioid receptors = blocked pain impulses
What are the 2 major metabolites of morphine?
M6G = active, contributes to analgesia
M3G = no analgesia, but causes side effects
How is morphine cleared from the body?
Cleared through kidneys
Can cause renal and hepatic impairment
What is the most serious side effect of morphine and what is the mechanism of action?
Respiratory Depression.
Due to decreased sensitivity to CO2 in the Respiratory Center of the medulla
What opioid side effects have a tolerance?
- Respiratory depression
- Sedation
- Urinary retention
- Nausea
What opioid side effects DO NOT have a tolerance?
- Constipation
- Orthostatic hypotension
- Cough suppression
What is rescue therapy for respiratory depression due to opioid use?
- Naloxone
2. Ventilator if needed
What is the management for sedation due to opioid use?
- Reduce/skip dose
- CNS stimulant (methylphenidate)
- Pts should avoid hazardous activities
What are management strategies for opioid-induced constipation?
- Be proactive!!
- Physical activity, increase fluids and fibre
- Stimulant/osmotic laxatives, enemas
- Methylnaltrexone (last resort)
STOOL SOFTENERS NO EFRECT
What is the mechanism of action for Methadone?
Blocks NMDA receptors and re-uptake of Serotonin and NE. Binds to mu and delta opioid receptors.
What are the opioid prodrugs and what do they convert to?
Codeine ➡️ morphine
Hydrocodone ➡️ hydromorphone
By CYP450
Oxycodone
Natural opioid with analgesic actions equivalent to codeine.
High abuse potential.
Codeine
Natural opioid used for mild to moderate pain, cough suppression, and diarrhea.
Converted to morphine in the liver.
What is a safety teaching note for oxycodone?
Swallow tablets and whole. Do not break, crush, or chew.
Can form a gelatinous substance in throat ➡️ choking hazard
Hydrocodone
Semi-synthetic opioid, similar analgesic to codeine.
PRODRUG converts to HYDROmorphone.
Aka Vicodin
What is a prototype of a partial opioid agonist?
Pentazocine (Talwin)
Agonist at kappa receptors, antagonist at mu receptors.
Opioid tolerance
Reduction in drug effect over time due to drug exposure. Increased doses needed to obtain same response.
Physical dependence
State in which abstinence Syndrome will occur with abrupt dose reduction or discontinuation, or administration an opioid antagonist.
What are the symptoms of Abstinence Syndrome?
- Yawning
- Rhinorrhea
- Diaphoresis
- Violent sneezing
- Weakness
- N/v
- Diarrhea + abdominal cramps
- Bone and muscle pain
- Muscle spasms
- Kicking movements
How long does abstinence Syndrome last if left untreated?
7 to 10 days
What is the classic triad of clinical symptoms for opioid overdose?
- Respiratory depression
- Coma
- Pinpoint pupils
What is the treatment for opioid overdose?
- Ventilatory support
2. Opioid antagonist (ex. Naloxone)
What are patient risk factors for opioid overdose?
- Elderly
- Renal/hepatic impairment
- Sleep disorders
- Using CNS depressants
- Cognitive impairment
- COPD
What are provider risk factors for opioid overdoses?
- Incomplete assessment
- Rapid titration
- Failure to monitor
- Inadequate pt education