EXAM #3: OPOID ANALGESICS Flashcards
What types of disease are opioid analgesics in to delay or arrest the disease process?
Autoimmune disease e.g. RA
Where do opioid analgesics exert their MOA?
Ascending:
1) At the damaged/inflammed peripheral nerve
2) Dorsal horn/ spinal cord
3) Thalamus
Descending pathways
What are the effects of opoids?
- Euphoria
- Analgesia
- Sedation
- Anti-diarrheal
- Cough suppression
What is opium?
Exudate from poppy seeds
What is an opiate?
Drug extracted from the exudate of a poppy seed
What is an opoid?
Natural or synthetic drug that binds to opoid receptors w/ agonist effects
What is a narcotic?
General term to categorize drugs that treat moderate to severe pain
What are the endogenous opoids?
Endorphins
Enkephalins
Dynorphins
Agonism of what subtype of opoid receptor produces the MOST analgesia?
Mu
Kappa and delta do produce some analgesia
What is the difference between Mu1 and Mu2?
Mu1= outside the CNS Mu2= inside the CNS
What is morphine metabolized to? What is unique about the metabolites?
Morphine undergoes glucuronidation to two products:
1) Morphine-3-glucuronide (90%)
2) Morphine-6-glucuronide (10%)
Morphine 6-glucuronide is MORE potent than morphine
What are heroin and codeine metabolized to?
Morphine
What happens upon Mu opoid receptor activation to produce analgesia?
- Mu opoid receptors are GPRCs coupled to Gi subunits
- Decreased adenylyl cyclase
- Decreased cAMP
–>Less intracellular Ca++ and increased K+ opening i.e. INHIBITION or neurotransmission
How do opoid analgesics inhibit the ascending pain pathways?
1) Inhibition of afferent pain transmission
2) Blocked peripheral effects
3) Blocked dorsal horn of the spinal cord
How do opioid analgesics affect the descending pain pathways?
Block inhibitory GABAergic interneurons
This leads to ENHANCED INHIBITION of nociceptive processing*
What is unique about the analgeisa produced by opioid analgesics?
Reduce BOTH the sensory and affective components of pain
What is an important adverse effect of opoid analgesics?
Respiratory depression
What should you keep in mind about opoid analgesics and head trauma?
1) Respiratory depression leads to increased Co2 tension
2) Increased Co2= reflexive cerebral vasodilation
This can be dangerous with head trauma
What is the effect of opioids on histamine?
Opioids can induce histamine release leading to urticaria
List the theraputic indications for opioids.
1) Analgesia
2) Anesthetic
3) Anti-tussive
4) Anti-diarrheal
5) Acute pulmonary edema
What class of drugs are contraindicated with opioids?
MAOIs
What specific opioid should be avoided if a patient is taking a MAOI?
Meperidine
What is the adverse reaction that happens with co-administration of Meperidine and MAOIs?
Hyperpyrexia
What is the prototype strong opioid agonist used for severe pain?
Morphine
