Opioids Flashcards
What is an opiate?
morphine-like (chemical)
What is an opioid?
morphine-like (pharmacological actions), also includes antagonist drugs
What is an endorphin?
endogenous opioid peptides: enkephalins, dynorphins, B-endorphins, endomorphins
What is a narcotic?
narcosis, stupor, sleep inducing (legal term)
What are the three main therapeutic uses of opioids?
analgesia, cough suppression, constipation
What about analgesia (4)?
- occurs without LOC
- pain is selectively decreased (no effect on other senses)
- continuous dull pain is better relieved than sharp intermittent pain
- morphinized pts still feel the pain but it is not as discomforting
What are the regions that express opioid receptors involved in analgesic actions of drugs (4)?
thalamus, dorsal horn, PG periaqueductal gray, RVM rostral ventral medulla
Ascending =
transmission of pain
descending =
modulation of pain
What’s involved in the ascending pathway?
C and Ad fibers, dorsal horn, thalamus
What’s involved in the descending pathway?
PG, RVM
What are additional CNS effects of opioids (3)?
euphoria, sedation, respiratory depression (OD)
When are opioids contraindicated? Who else should they be used cautiously in?
in head trauma-respiratory depression and CO2 retention->cerebral artery vasodilation->increase in intracranial pressure. COPD, asthma
Do opioid receptor antagonists block the effect of cough suppression?
no
Two more effects of opioids? think eyes and blergh
miosis (constriction of pupil)- no tolerance to this effect. emesis: nausea and vomiting, primarily a first dose effect
How do opioids cause constipation? is there tolerance to this effect?
acts on nerves, not on smooth muscle or secretory cells. increased muscle tone in duodenum and antrum of stomach, decreased peristaltic movement in jejunum and colon. yes-intermediate tolerance
What do opioids do to the biliary tract?
constriction of sphincter of Oddi-rise in pressure in common bile duct
What do they do to the CV system?
no effect on HR and BP. opioid agonists can stimulate release of histamine and thereby cause hypotension
what are three minor effects?
urinary retention, slight decrease in body temp, convulsions at high doses
What are the three subtypes of opioid receptors?
Mu, kappa, delta. they are G-protein coupled
What’s up with mu receptors?
morphine-preferring. many clinically used drugs are selective for this receptor. mediates spinal and supraspinal analgesia. respiratory depression, niosis, GI effects.
Which drugs are selective for mu receptors?
Endomorphins (highly), B-endorphin also have high affinity