Drug
misuse
Psychotropic drugs are taken
as a result of positive reinforcement, e.g. alcohol, cocaine, opium, nicotine,
eating and sex all increase dopamine activity.
Dependence – a pattern of
repeated self –administration that usually results in tolerance, withdrawal and
compulsive drug taking behaviour.
Nicotine
Causes stress, tension,
depression and irritability
Smokers feel normal with
nicotine but abnormal without it
Nicotine binds to
acetylcholine receptors in the PNS and CNS
Causes increased activity of
dopamine, noradrenaline, glutamate and serotonin
Increases heart rate by 10
beats per minute via sympathetic effects, so may increase BP and cardiac
distress directly.
Alcohol
Types of drinker
1. Social
2. Problem drinker, this
will lead to physical, psychological or social harm
3. Heavy drinker, medically
unsafe in the long term
4. Binge drinkers, people
who drink excessively over a period up to 48 hours
5. Alcohol dependent
drinkers, have a physical dependence on alcohol, `alcohol dependency syndrome`.
Delirium tremens (DTs)
Occurs 1 – 3 days after
alcohol cessation.
Features
Disorientated, agitated,
tremor, hallucinations, sweating, tachycardia, tachypnoea, pyrexia
Complications
Dehydration, infections,
hepatic disease, Wernick-Korsakoff syndrome
Solvents
Have an intoxicating effect
Death may occur through
asphyxiation or acute poisoning
Amfetamines
Stimulate the release of
monoamines from presynaptic neurone, so act as an indirect agonist
Cause stimulation and
euphoria followed by fatigue and depression.
Acute paranoid psychosis may
develop, same as acute paranoid schizophrenia
Ecstasy
3, 4-methylenedioxy-methamfetamine
(MDMA) is an amphetamine derivative
Psychodelic dance or rave
drug, acts for 4-6 hours
Ongoing use can cause neurotransmitter
changes in the brain
Can cause malignant
hyperpyrexia and dehydration.
Acute renal or hepatic
failure are possible.
Cocaine
CNS stimulant with similar
effects to amfetamines
Derived from South American
coca trees
Free base or `crack` cocaine
can be smoked
Increases dopamine activity
Hallucinogenic drugs
Lysergic acid diethylamide,
mescaline, psilocybin
Frank hallucinations with
possible long term psychosis.
Bind to serotonin receptors
Cannabis
Exaggerates the pre-existing
mood
Some analgesic and
antiemetic properties
Regular use leads to an
amotivational syndrome
Cannabis binds to a specific
CNS receptor
Tranquillizers
Benzodiazepines and
barbiturates
Benzodiazepines increase
GABA activity
Rebound effects may occur
Opiates
Physical dependence occurs
with opium, morphine codeine and heroin
Also occurs with synthetic
compounds such as methadone and pethidine
Opiates bind to endorphin
receptors
Tolerance is marked
Associated with complications
of injecting
Have a severe withdrawal
syndrome, worst after 2 – 3 days but recovery occurs after a week.