Opioid Narcotic Analesics And Related (Fitz) Flashcards
List generic names of soluble, bioavailable, opioid narcotic agonists used for analgesia/other indications
Codeine Fentanyl Heroin Hydrocodone Hydromorphone Meperidine Methadone Morphine Oxycodone Oxymorphone Tramadol
List generic names for opioid narcotic mu receptor antagonists used for management of opioid narcotic overdose/addiction/side effects
Naloxone
Naltrexone
Methyl naltrexone (GI specific)
List generic names of opioid partial agonists or mixed agonists/antagonists
Buprenorphine
Buprenorphine-naloxone
Pentazocine
List generic names of insoluble, poorly absorbed opioid receptor agonists used for diarrhea
Loperamide
Diphenoxylate
List generic names of most common opioid related anti-tussive agents (cough suppression)
Codeine
Dextromethorphan
Hydrocodone
What are the types of opioid receptors and their physiological ligands?
Ligands are peptides
Mu MOR: endorphins
Kappa KOR: dynorphins
Delta DOR: enkephalins, endorphins
Where are the opioid sites of action in the CNS/PNS?
Cortex and limbic system: thalamus and hypothalamus
Midbrain: periaqueductal gray
Medulla: reticular formation, locus ceruleus, raphe nuclei
Spinal cord: spinothalamic (mescencephalic, reticular tracts)
Describe the pain impulse at pre and post synaptic neurons. Describe opioid agonist-mediated signaling
Opioid receptors unoccupied
- Afferent sensory signal
- Increases Ca2+ influx (presynaptic)
- Increases glutamate discharge (presynaptic)
- Increases NMDA receptor-Na+ influx (postsynaptic)
Opioid agonist occupies opioid receptors
- Blunts afferent signal
- Blunts Ca2+ influx
- Blunts glutamate discharge
- Increases K+ efflux
Of the drugs that bind to mu opioid receptors, which are full agonists, partial agonists, and antagonists?
Full agonists:
Fentanyl
Morphine
Partial agonist/mixed
Buprenorphine
Mu/kappa mixed:
Pentazocine
Antagonist
Naloxone
Naltrexone
In detail, describe opioid binding and receptors
Opioids bind to G-protein-linked membrane receptors: mu, kappa, delta. Subtypes, splice variants confer diversity
Receptors are widely distributed throughout human body, including brain, spinal cord, gut, uterus, etc. Majority of clinically useful opioid analgesic drugs have significant agonist activity at mu receptors
Opioid receptors bind endogenous peptides and drugs
Describe the pain treatment ladder based on opioid-sparing rationale
Mild pain:
-NSAID, acetaminophen
Moderate/persisting/uncontrolled:
- Codeine
- Codeine-related +/- acetaminophen
- tramadol
Severe/persisting/uncontrolled:
- Morphine
- Fentanyl
- extended release forms
List analgesic mechs and clinical utility
Acetaminophen,NSAIDS
COX-1,-2
Tissue injury»acute or nerve injury
Opioids, prototype morphine
Mu receptor agonists
Tissue injury=acute stimuli>nerve injury
Anticonvulsant (gabapentin)
Ca2+ channel antagonists
Nerve injury>tissue injury=acute
Antidepressants (amitryptilene)
Reuptake inhibitor
Nerve injury>tissue injury»acute stimuli
What is the prototype mu agonist?
Morphine
Describe clinical effects of agonists acting on mu receptor MOR
Analgesia (supra-spinal) Euphoria CNS and respiratory depression Drug dependence Miosis (pupil contraction) GI, uterine motility
Describe clinical effects of agonists acting on kappa receptor KOR
Analgesia (spinal)
Sedation
Miosis
GI, uterine motility
Describe tolerance to morphine (mu agonist)
Tolerance: over time, for a given dose, response deteriorates, necessitating increase in dose or rotation to different opioid
-analgesia, euphoria, sedation, nausea, respiratory depression
No tolerance to
-miosis, constipation
Patient was recovering from surgery in post-anesthesia care unit (PACU). He had been receiving morphine IV for 2 hr for postsurgical pain. His resp rate was 7 per minute with shallow breaths. He did not respond to any stimuli
pH=7.15 (normal 7.4)
HCO3=22 (normal 24)
PaCO2=68 (normal 40).
Describe what happens with opioid and respiratory depression
- At baseline, pH7.4=normal
- Hypoventilation. Lungs retain CO2=retain acid
- CO2 contributes to H+ to blood - Rise in PaCO2=rise in H+
PH=7.15
Increase in CO2 + H2O H2CO3 Increase in H+ + HCO3
Describe morphine-induced respiration depression. Contraindciations to morphine?
Morphine (mu agonist) depress sensitivity to CO2
Dose-related drop of respiration rate (3-4/minute in severe toxicity), minute volume, tidal exchange
Contraindications:
- Brain injury
- Emphysema