Heroin —————- Diamorphine Hydrochloride
Heroin is an opiate, which acts as a depressant and analgesic (painkiller) in the central nervous system. It is produced from morphine, which comes from the opium or Asian Poppy.
Mode of Action:
Heroin acts at the opioid receptor sites in the brain. It changes the action of dopamine in the reward pathway of the brain, releasing more dopamine than usual. Heroin is converted into morphine that works at the opioid receptors at the synapse. The morphine binds to receptors to reduce the inhibitory (preventing) effect of GABA on dopaminergic neurones (those that release dopamine). The result is more dopamine activity and the release of dopamine into the synaptic cleft. If the dopaminergic reward pathway continues to be stimulated, this leads to feelings of euphoria.
Heroin User
Heroin mimics the effects of endorphins (pleasure). It is therefore an agonist.
During everyday activity, a moderate amount of endorphin is naturally produced, causing the release of dopamine and facilitates the reward systems in the brain. Heroin acts like a massive release of endorphin in the brain. The heroin floods the endorphin receptors, stimulating the two actions of endorphins. Large quantities of dopamine are released, activating the reward system and producing feelings of well-being.
Effects:
Short-term Effects:
- Pleasure
- Reduction of pain
- A ‘rush’ (dry mouth, heavy limbs, flushing of the skin, feelings of sickness and severe itching)
- A sense of relaxation
- Drowsiness
- Slowing of breathing and heart rate
- Pupil constriction
- Constipation
Long-term Effects:
- Collapsed veins and infections (through the use of needles)
- Clogging of blood vessels
- Difficulty in concentrating
- Lack of attention
- Memory problems
- Increased risk of miscarriage
- Death (may occur if the user stops breathing)
Tolerance
Tolerance means that, as a drug is taken increasingly over a period of time, more of it is needed to obtain the feelings that were first produced. The same dose of drug will not produce the same feeling of euphoria. Tolerance goes with being physically dependent. It is also linked to addiction.
Studies have shown dosage rates can increase tenfold in three to four months (Griffiths, Bigelow and Heningfield, 1980). Regular uses take heroin at a high enough level to kill a non-user.
Withdrawal:
Even if heroin is taken (in a sustained way) for only three days, withdrawal symptoms can occur when it is stopped.
Immediate symptoms include:
- Pain
- Nausea
- Sweating
- Diarrhoea
- Extreme anxiety
- Depression
Symptoms start 6 – 12 hours after the last fix. These symptoms peak after 26 – 72 hours.
Sources:
- Russell, J. (2011). Angles on psychology. Haddenham: Folens.
- Brain, C. (2009). Edexcel A2 psychology. London: Edexcel.
- Brain, C. (2009). Edexcel A2 psychology. London: Philip Allan.
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