Opioids Flashcards
difference bw opiates and opioids
opiates -> everything derived from poppy (natural opium products)
opioids -> including semi-synthetic and synthetic substances (actions similar to morphine; reacting with opioid receptors as agonist or antagonist)
what can influence the potency of opioids
their structure
characteristics of codeine (3)
- weaker analgesic
- fewer side effects
- cough suppressant
characteristics of heroin compared to morphine (3)
- 2-4x stronger IV
- quicker action
- more liposoluble
what is naloxone
opioid antagonist (binds to receptor and blocks effect); also partial inverse agonist (blocks receptor + makes opioids leave the receptor); induces withdrawal when in overdose
natural narcotics (4)
- opium
- morphine
- codeine
- thebaine
semisynthetic narcotics (4)
- heroin
- hydromorphone (dilaudid)
- oxycodone (percodan)
- etorphine
synthetic narcotics (6)
- pantazocine (talwin)
- meperidine (demerol)
- fentanyl (sublimaze)
- methadone (dolophine)
- LAAM
- propoxyphene (darvon)
endogenous opioids (4)
- enkephalins
- endorphins
- dynorphins
- endomorphins
(a) absorption (b) medical administration ways (c) recreational administration ways (d) metabolism of opioids
(a) only small fraction crosses BBB, but can easily cross placenta barrier
(b) IM, PO
(c) inhalated, intranasal, subcutaneous, IV
(d) metabolized by liver, metabolites excreted in urine in 24h
why do inhalated or IV opioids act faster that in pill (oral) or subcutaneous form
go into oxygenated blood, which goes straight to the brain; pill is slower because takes a while to be absorbed and is metabolized (loses potency) ad subcutaneous slows absorption
what is the main active ingredient of narcotic analgesics
morphine
what allowed doctors to prescribe specific doses of painkillers
identification of main active ingredient of narcotic analgesics
what influences psychological and behavioral effects of opioids (2)
dose and speed of absorption
main subjective effects of weak doses of opioids (5-10 mg) (3 elements)
- sleepiness
- reduced sensitivity to the environment
- decreased focus
elements of psychological pain that weak doses of opioids (5-10 mg) target (3)
- reduced anxiety
- reduced feeling of inadequacy
- reduced hostility
main effects of weak doses of opioids (5-10 mg) (3 elements)
- pain relief
- respiratory depression
- miosis (pupil constriction)
what is morphine used for (not pain)
cough suppressant
brain area (1) that morphine acts on and effects (4)
hypothalamus; decreased appetite, drop in body temperature, reduced sex drive, variety of hormonal changes
positive effects of high doses of opioids (> 10 mg)
euphoria, elation, ‘whole-body orgasm’
negative effects of high doses of opioids (> 10 mg) (4 elements)
- dysphoria
- agitation
- anxiety
- nausea and vomiting
effects of highest doses (close to overdose) of opioids (5 elements)
- sedative (loss of consciousness)
- drastic decrease in temperature
- drastic decrease in BP
- severe respiratory depression
- miosis
main peripheral effect of opioids and why
constipation -> because the receptor it binds to also plays a role in the digestive tract
which medication plays on the constipation side effect of opioids and what does it treat
loperamide -> treating diarrhea (no effect on CNS, but effect on GIT)
tolerance of peripheral side effects of opioids
there is no tolerance to constipation
what is the usual cause of death of people who consume opioids
respiratory depression -> cardiac arrest
subtypes of opioid metabotropic receptors (4)
- mu
- delta
- kappa
- nociceptin/orphanin FQ (NOP-R)
characteristics of mu receptors (2)
- high affinity for morphine and derivatives
- widespread in the brain and spinal cord
roles of mu receptors (4)
- morphine-induced analgesia
- feeding and positive reinforcement
- CV and respiratory depression, cough control and nausea/vomiting
- sensorimotor integration
brain regions regulating (a) morphine-induced analgesia (4) (b) feeding and positive reinforcement (c) CV and respiratory depression/cough control/nausea & vomiting (d) sensorimotor integration (2)
(a) medial thalamus + periaqueductal gray + median raphe (raphe nuclei) + spinal cord
(b) NAcc
(c) brainstem
(d) thalamus + striatum
(also located in amygdala and hippocampus)
in which brain region are delta receptors predominant (5)
forebrain:
1. neocortex
2. striatum
3. olfactory areas
4. substantia nigra
5. NAcc
(also spinal cord)
roles of delta receptors (4)
- olfaction
- motor integration
- reinforcement
- cognitive functions
(also analgesia)
do delta receptors have a role in analgesia
they overlap with mu receptors suggesting modulation of spinal analgesic response (so yes)
location of kappa receptors (5)
- striatum
- amygdala
- hypothalamus
- pituitary
- NAcc
roles of kappa receptors (8)
- regulation of pain perception
- gut motility
- dysphoria
- water balance
- feeding
- temperature control
- neuroendocrine/hormonal function
- analgesia
location of NOP-R receptors (9)
- cerebral cortex
- amygdala
- hypothalamus
- hippocampus
- periaqueductal gray
- thalamus
- substantia nigra
- brainstem nuclei (including raphe nuclei)
- spinal cord
roles of NOP-R receptors (7)
- spinal analgesia
- feeding
- learning
- motor function
- neuroendocrine regulation
- mood -> limbic effect (5-HT, NE)
- perception of pain
which receptors are important for withdrawal symptoms
kappa receptors -> neuroendocrine/hormonal problems when stop use
endogenous ligands of 4 receptors
mu -> endomorphins, endorphins
delta -> enkephalins, endorphins
kappa -> dynorphins
NOP-R -> nociceptin, orphanin, FQ
what can increase the risk of respiratory depression
mixing alcohol with opioids
where do endogenous peptides imitating morphine come from
precursor peptides (propeptides; inactive) -> broken into smaller active opioids by proteases in golgi apparatus + axonal transport in vesicles
effect of electrostimulation of specific regions in CNS
produces analgesia -> effect partially reduced with opiate antagonist
inhibitory mechanisms of endogenous opioids (3)
- postsynaptic inhibition
- axoaxonic inhibition
- presynaptic autoreceptors
which protein are the 4 receptor subtypes linked to
Gi protein (inhibitory GPCR)