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Mode of action of heroin

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Georgia Pine

on 14 January 2015

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Transcript of Mode of action of heroin

Mode of action
Stimulates opioid receptors and mimics the effects of endorphins.
Endorphins reduce pain and provide rewards.
The attachment of these molecules to receptors inhibits the release of GABA.
As GABA serves to prevent dopamine release, this action stimulates the release of dopamine, which is extremely rewarding.
So indirectly, heroin causes a massive rise in dopamine in the synapses of affected brain areas, specifically the nucleus accumbens.
Rapid feeling of euphoria.
The analgesic (release of pain) effect gives a feeling of calm and aches and pains disappear.
It also depresses most of the body's activity, so breathing and heart rate becomes dangerously slow and the user feels sleepy and relaxed.
Peripheral blood vessels dilate causing the user to feel flushed, warm and sweaty. It gradually depresses activity of the vomiting center, so feelings of nausea gradually disappear.
Digestion also slows resulting in chronic constipation.
Develops very quickly and results in cross tolerance to all similar drugs.
Dosage rates can increase tenfold in 3-4 months, which would kill a non-user.
The slowing down effect on the body's mechanisms does not develop tolerance.
Thus, heart rate stays slow, causing low blood pressure, breathing is depressed and because the digestion system is under active the user may be permanently constipated.
Sex drive is also likely to be very low.
Prolonged abstinence may also result in depression.
Mini Test - What do the pictures relate to?
Psychological dependence
The makes the addict cease to be concerned with maintaining contact with family and friends, as the focus of life becomes finding the next fix.
Even with the readily-available supplies the addict may become dissatisfied with life.
When not in the immediate effects of heroin they tend to feel increasingly confused, anxious, restless and paranoid.
Such psychological symptoms can only be removed by more of the drug or treatment.
action of heroin
opioid receptor
reduce pain
stops release of gaba
it can't stop dopamine/ more dopamine is released
Dopamine is kind of like the fun friend at a party. There's nothing particularly wrong when they're not invited, but it's definitely better with them around.

The same goes for dopamine. When the release of dopamine is stimulated, it's extremely rewarding.
indirectly heroin causes a massive rise in dopamine in synapses of affected brain areas.
Like if the brain was a club, it would suddenly be filled with loads of those really fun friends (dopamine)
Physical Dependence
Develops very quickly, just one fix can produce withdrawal symptoms within 12 hrs i.e. the brain gets used to the drug very quickly.
The addict takes fixes to avoid the increasingly severe withdrawal symptoms.
However, as tolerance builds the amount taken increases, dependency gets greater and withdrawal symptoms worsen.
Because of this overuse, down regulation means that the brains opioid receptors stay the same in number yet become less sensitive.
This means more of the drug is needed to maintain normal brain functioning.
Symptoms start 12 hours after last use.
User becomes agitated and often very aggressive.
Initially, user is agitated and restless and then they alternate between hot and cold flushes and the skin develops goose bumps (i.e. the cold turkey).
Breathing becomes short and jerky. They may then sleep for 12 hours and wake to cramps, diarrhoea, sweating, shaking and twitching of the limbs.
Symptoms peak after 26-72 hours, but most are over within a week.
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