Opioids (Dr. E's Lecture) Flashcards
Please note that the drug card information is for Educational Use ONLY, and the source is from Carrie Bowman's glossary of drug cards permitted by use of Georgetown NAP students. No permission is given to use these cards for anything other than as a study resource for our program.
What does the word “opioid” refer to?
all substances, natural and synthetic, that bind to opioid receptors and produce an agonist effect
What are the naturally occurring opioids?
Morphine
What are the Semisynthetic opioids?
Analogs of morphine
Heroin, Hydromorphone, Codeine
What are the 4 subdivisions of the synthetic (exogenous) opioids?
- Morphinan derivatives
- Diphenyl derivatives
- Benzomorphans
- Phenylpiperidines
What are the synthetic opioids of morphinan derivatives?
Levorphenol
Butorphenol
What are the synthetic opioids of Diphenyl derivatives?
Methadone
What are the synthetic opioids of Benzomorphans?
Phenazocine
Pentazocine
What are the synthetic opioids of Phenylpiperidines?
Meperidine Fentanyl Alfentanil Sufentanil Remifentanil
how does a partial agonist work?
regardless of the dose the drug cannot produce full mu receptor effects like morphine
How do agonist/antagonists work?
agonist at one receptor, kappa and antagonist at mu reversing respiratory depression
What are the 3 endogenous agonists?
Enkephalins, Endorphins, Dynorphins
Opioid receptors are activating pain _____________ systems. which are?
- Antinocioceptive
- Inhibiting excitatory Neurotransmitters (ie substance P)
Where are mu receptors primarily?
in the brain and spinal cord
Tell me all about the mu-1 receptor
- Analgesia
- Euphoria
- Supraspinal (and spinal to lesser degree)
- Miosis
- Bradycardia (direct central vagal activity)
- Urinary retention
- All endogenous and synthetic agonists act on these receptors
Tell me all about the mu-2 receptors
- Hypoventilation
- Physical dependence
- Spinal analgesia (and some supraspinal)
- Constipation (marked)
- all endogenous and synthetic agonists act on these receptors
tell me about the kappa receptor
- Supraspinal and spinal analgesia
- Dysphoria
- Sedation
- Miosis
- Only DYNORPHINS act on these receptors
- some agonist/antagonist such as Butorphenol also act there
Tell me about the delta receptor
- Supraspinal and spinal analgesia
- Hypoventilation
- Physical dependence
- Constipation (minimal)
- urinary retention
- Only ENKEPHALINS act on these receptors
In a nutshell, tell me all of the effects of Mu-1
- supraspinal
- bradycardia
- euphoria
- sedation, prolactin release
- hypothermia
- catalepsy
- Indifference to environmental stimulus
- miosis
- urinary retention
- low abuse potential
In a nutshell, tell me all of the effects of Mu-2
- spinal
- bradycardia
- resp. depression
- euphoria
- pruritis
- dopamine turnover
- possible growth hormone release
- miosis
- inhibition of peristalsis
- n/v
- urinary retention
- Can cause physical dependence
In a nutshell, tell me about the effects of Kappa
- Supraspinal, spinal
- possible resp. depression
- sedative dysphoria
- psychotomimetic reactions (hallucinations, delirium)
- miosis
- diuresis (inhibition of vasopressin release)
- low abuse potential
In a nutshell, tell me about the delta receptor
- supraspinal, spinal
- modulate mu receptor activity
- Resp. depression
- Urinary retention
- pruritis
- physical dependence
What type os receptor is the opioid receptor?
G protein coupled- G-alpha-i and G-alpha-o
What are the effects of an opioid binding to the receptor? (4)
- (+) K channel inward rectifier (increases outward K flow to hyperpolarize cell)
- (-) decreases conversion of adenyl cyclase to cAMP
- (+) MAPK cascade: 1. gene expression and 2. Phospholipase A2 (production of prostaglandins and leukotrienes)
- (-) Voltage-dependent Ca channel (N-type)->suppression of neurotransmitter release (sub. P)
What is the MOA of the opioids on the receptors?
- opioid receptors exist on the peripheral ends of primary afferent neurons
- activation of receptors either
1. directly decreases neurotransmission or
2. inhibits the release of excitatory neurotransmitters (ie. Substance P)
What are the pharmacokinetic features of the opioids regarding the onset of action?
-Weak Bases
-Only unionized & unbound opioids can diffuse from blood to target tissue thus:
~higher % unionized the higher diffusible fraction and the faster the onset
~higher % unbound the faster the onset
Why does morphine have a slower onset of action?
because its % nonionized at physiologic pH is only 23%
Why does Alfentanil have a very rapid onset of action?
b/c it has a high % unionized (89%) at pH 7.4
What are the pharmacokinetic features of the opioids regarding the volume of distribution?
-Vd= dose of drug at time 0/ plasma [ ] b4 elimination occurs
-Larger Vd equates to a longer duration of action
-Vd related to lipid solubilty (1st, most important parameter), protein binding (2nd), (and 3rd molecular size/structure)
-higher lipid solubility=Larger Vd, longer DOA!
~more lipid soluble the more potent these drugs are
-Redistribution and fast termination of effect b/c of drug redistributing to other sites and is gone from the effect sites