Opiates Flashcards
what is morphine
refined active ingredient of the opium poppy
what is codeine
substitution of one group in morphine produces codeine
less analgesic effect but fewer side effects
potent cough supressant
what is heroin
derivative of morphine
3X as potent (more lipid soluble)
Addition of acetyl group increases oil water coefficient
Once inside the brain, acetyl groups are removed making morphine
what are characteristic opiate effects
dreamy, euphoric state, lessened sensation of pain, slowed breathing, constipation, pinpoint pupils
what is fentanyl
80x more potent than morphine
mostly used for anesthesia and neuropathic pain
similar effects to heroin but more potent
what is carfentanil
10,000x more potent than morphine
100x more potent than fentanyl
depressed the CNS and ability to breathe
what are the medical uses of opiates
relief of severe pain (analgesic)
treatment of acute diarrhea
cough suppression
what are the routes of administration for medical use of opiates
oral
transdermal
mucous membranes
intravenous
what are the routes of administration for recreational use of opiates
inhalation
mucous membrane
subcutaneous
intravenous
what is the distribution of opiates
high levels usually not present in the brain (except for heroin)
How are opiates excreted
90% of morphine in metabolized by liver and excreted as urine; 10% as pure morphine
what effects do opiates have on the PNS
constricts pupils
decreases GI motility
dilation of peripheral blood vessels
warm, flushed skin due to dilation of subcutaneous blood vessels
itchy skin (release of histamines)
what effects do opiates have on the CNS
Analgesic
-Actions in medulla suppress cough and decrease rate and depth of breathing
- Depresses release of NT associated with pain
Reduces “psychological” pain
-pain signals aren’t experiences as unpleasant
- Acts on the limbic system
Sedative effects
-depress neuronal firing rate
what part of the brain do opiates effect to produce the sedative/hypnotic effects
cerebral cortex
what part of the brain do opiates effect to produce the euphoric effects
limbic system/nucleus accumbens
what part of the brain do opiates effect to produce analgesic effects
brainstem, spinal cord, and thalamus
what part of the brain do opiates effect to produce the respiratory depression, suppression of cough reflex, and nausea/vomiting
medulla
what are the opiate receptors
mu
delta
kappa
- all metabotropic
what happens when opiate receptors are activated
decrease in neuronal activity
How do opiates produce euphoria
heroin is converted to morphine in the brain which acts on the mu and delta receptors expressed on GABA neurons; Reduced amount of GABA disinhibits the VTA causing increase of DA release
what shows the fastest tolerance in opiate use
tolerance to euphoria effects
what are effects of opiates that show little to no tolerance
constipation
pupil constriction
what kinds of tolerance can you develop to opiates
Metabolic tolerance
- increase in liver enzymes
Receptor desensitization/down-reg.
Context Dependent tolerance
- likely to be attached to cue
Describe dependence to opiates
both psychological and physical dependence can develop
Describe physical dependence to opiates
serious and unpleasant withdrawal
intensity and duration of withdrawal directly correlated to intensity and duration of drug effects
withdrawal NEVER fatal on its own
what are opiate withdrawal symptoms
6 hours: drug craving, anxiety, restlessness, agitation
12-14 hours: yawning, increased agitation, perspiration
14-16 hours: hot and cold flashes, goosebumps, tremors, muscle aches
24-36: stomach, back and leg cramps, uncontrolled movements of limbs, nausea and vomiting, sweating
36-48: fetal position, vomiting, diarrhea
what are the leading factors in opiate overdose
1) concentration of drug bought on black market is high than the accustomed concentration
2) Patient abstains from use, relapses, then uses same amount before withdrawal
3) drugs in combination
4) context specific tolerance
treatment of opiate dependence
Antagonist treatment (naloxone)
Maintenance therapy (methadone)
- Opiate Agonist
what is methadone
Long acting mu receptor agonist with pharmacological properties similar to morphine
- blocks effects of other opiates, suppresses withdrawal, decreases craving
what is buprenorphine
partial agonist
