Pain and Opioids Flashcards
Fast pain fibers are:
a) Unmyelinated A-delta fibers
b) Myelinated A-delta fibers
c) Unmyelinated C-fibers
d) Myelinated C-fibers
b)Myelinated A-delta fibers
Slow pain fibers are:
a) Unmyelinated A-delta fibers
b) Myelinated A-delta fibers
c) Unmyelinated C-fibers
d) Myelinated C-fibers
c) Unmyelinated C-fibers
Define Eudynia.
Symptomatic/”Normal” pain
Define Maldynia.
“Abnormal” pain-pathophysiologic disease of the nervous system
True/False
Chronic pain is protective and usually adequately treated by pharmacological methods.
FALSE
Chronic pain is non-protective (has NO biological use) and is difficult to treat. Chronic pain is a disease.
Define Allodynia.
Pain to non-painful stimuli.
Define Hyperalgesia.
Heightened pain response to painful stimuli.
What 2 substances are released to allow transmission of pain?
Glutamate
Substance P
What are the 3 Main Opioid Receptors?
Mu, Delta, and Kappa
Name four Endogenous Opioids.
Endomorphins, Endorphins, Enkephalins, Dynorphins
True/False
Opioids can cause the release of histamine.
TRUE
Morphine
1) Mechanism of Action
2) Onset of Action
1) Classic Mu Opioid receptor Agonist-binds to G-protein coupled opioid receptor to block pain transmission
2) Slow Onset of Action (Low lipid solubility)
Does Morphine cross the BBB?
Yes, b/c Morphine is Non-Ionized
Does Morphine have an Active Metabolite?
Yes, M-6-Glucuronide (M6G) which is 10x more potent
*Must be careful in Kidney disease d/t kidney excretion
Codeine
1)Mechanism of Action
Morphine Derivative
ProDrug that’s converted to Morphine via CYP2D6
*Commonly combined w/Acetaminophen
Hydrocodone
1)Mechanism of Action
Morphine Derivative
ProDrug that’s converted to Hydromorphone via CYP2D6
*Commonly combined w/Acetaminophen
Hydromorphone
1)Mechanism of Action
Morphine Derivative
5x More potent than Morphine
More lipid soluble=Faster Onset of Action than Morphine
Oxycodone
1)Mechanism of Action
Morphine Derivative
ProDrug that’s converted to Oxymorphone via CYP2D6
*Commonly combined w/Acetaminophen
**Oxycontin=Sustained Release formula
Methadone
1)Use
Morphine Derivative
Use: Addictive patient’s maintenance and Chronic pain
*ULTRA-LONG half-life
Meperidine
1) Mechanism of Action
2) Onset of Action
3) Use
4) Adverse Effects
1) Synthetic Opioid: mu and kappa Opioid Receptor Agonist *1/10th potency of Morphine
2) More lipid Soluble than Morphine=Faster Onset
3) Post-operative Shivering, Pain
4) Psychomimetic effects (d/t kappa action), Histamine release (more than morphine)
Why is Meperidine contraindicated to use w/MAOIs and SSRIs?
Serotonin Syndrome: Meperidine inhibits serotonin re-uptake
Symptoms: Delirium, Fever, Convulsions
Does Meperidine have an active metabolite?
YES, Normeperidine
Fentanyl
1) Mechanism of Action
2) Onset of Action
3) Adverse Effects
1) Synthetic Opioid: Mu receptor agonist
* 50-100x MORE potent than Morphine
2) Short Onset of Action
3) Metabolized by CYPs
Alfentanil
1) Mechanism of Action
2) Onset of Action
1) Synthetic Opioid: Mu receptor agonist
* 10x MORE potent than Morphine
2) Extremely Rapid Onset of Action
Remifentanil
1) Mechanism of Action
2) Onset of Action
3) Adverse Effects
1) Synthetic Opioid: Mu receptor agonist
* Equipotent to Fentanyl
2) Extremely Rapid Onset of Action AND Clearance (3min)
* Metabolized by Non-specific Plasma Esterases
3) Little Post-op Pain Relief
What does Context Sensitive Half-life mean?
Half-life of the Drug depends on Administration Length of Time (Longer infusion time=Longer Half-life)
“Context” is the duration of infusion.
From the Drugs listed below, which have Context Sensitive Half-lives? Morphine Alfentanil Remifentanil Fentanyl
Alfentanil and Fentanyl
What is Opioid Synergism?
Opioid + Benzo OR Opioid + Propofol
–> causes significantly greater respiratory depression, obtundation, and respiratory arrest at much lower doses of these agents when used together
True/False
Spinal Opioids with preservatives are safe to use.
FALSE, Spinal Opioids MUST be Preservative FREE!
Tramadol
1) Mechanism of Action
2) Use
3) Adverse Effects
1) Opioid Partial Agonist: binds to mu receptor partially and inhibits re-uptake of monoamines (NE and Serotonin)
2) Mild/Moderate Acute and Chronic Pain
3) Metabolized by CYPs-can cause drug-drug interactions
Tapentadol
1) Mechanism of Action
2) Use
3) Adverse Effects
1) Opioid Partial Agonist: binds to mu receptor partially and inhibits re-uptake of monoamines (NE and Serotonin)
* Greater mu receptor efficacy than Tramadol
2) Mild/Moderate Acute and Chronic Pain
3) Metabolized by CYPs-can cause drug-drug interactions
Nalbuphine
1) Mechanism of Action
2) Use
1) Kappa Opioid receptor agonist AND Partial mu Opioid receptor antagonist
* Positive Opioid Benefits w/Fewer side effects
2) Short term, Acute, Moderate/Severe Pain
* Does NOT work for Chronic Pain
Pentazocine
1)Mechanism of Action
1) Has 2 Isomers–> One has affinity for kappa Opioid receptor, other does NOT
* Has a “ceiling effect”- once max dose reached, NO additional agonists effects occur
Buprenorphine
1) Mechanism of Action
2) Use
1) Partial mu Opioid receptor agonist and kappa Opioid receptor antagonist
* High affinity for mu receptor=difficult for other Opioids to bind
2) Opioid Addiction (must use high doses)
Nalozone
1) Mechanism of Action
2) Use
1) Opioid Antagonism: competitive antagonist at mu, kappa, and delta receptors
* Causes REVERSAL of ALL Opioid effects
2) Acute Opioid Overdose
* May require multiple dosing d/t half-life of OD drug vs. reversal agent
Naltrexone
1) Mechanism of Action
2) Use
1) Opioid Antagonism: competitive antagonist at mu, kappa, and delta receptors
* ORAL agent=slower acting
2) Maintenance treatment for Opioid dependence
Which Opioids below have Active Metabolites? Morphine. Codeine Hydrocodone. Fentanyl Meperidine. Methadone Oxycodone. Oxymorphone Tapentadol. Tramadol
Morphine Hydrocodone Meperidine Oxycodone Codeine Tramadol
