|
10. Amphetamines
In the past, amphetamines have been used to treat a number of medical conditions such
as epilepsy, obesity, narcolepsy, depression and hyperkinetic children. Since amphetamines
were prescribed and promoted quite readily after World War II, people assumed that these
drugs were less harmful, if harmful at all. Recent studies, however, have shown
amphetamines to be both potentially addictive and quite toxic. Another concern are the
recent signs of increased availability and use, and the knowledge that amphetamines can be
bought quite cheaply.
The best known members of this group of stimulants in Australia, in decreasing order of
potency, are dexamphetamine (eg dexedrine), methamphetamine (eg methedrine) and the
amphetamines (eg benzedrine).
Amphetamines are potent sympathomimetic amines of a simple structure with a
multiplicity of biological effects that include hyperthermic, anorectic, cardiovascular
and central nervous system stimulant actions. The stimulant action of amphetamines is
similar to the naturally occurring hormone adrenalin and is thought to work by stimulating
and exciting all areas of the nervous system, including the brain.
Since a major action of amphetamines is to inhibit sleep and fatigue, a present concern
is the self medication of amphetamines by truck drivers, students and businessmen, who use
amphetamines to stave off normal fatigue and enable them to work for days with little
sleep or food.
- Young males
- Those who frequent nightclubs an effect of amphetamine use is that it facilitates
energy and activation allowing users to dance all night
- Students, particularly at exam time
- Truck drivers it allows them to drive for long periods without rest and make more
trips per week
- Those people who are prescribed amphetamines for medical purposes and who develop a
dependence for them eg diet pills (Duromine)
- The drug has a reputation of facilitating social and sexual interactions:
- implications for HIV transmission, ie if enhanced sexuality is not accompanied by safer
sexual practices
- amphetamines are often used in a casual fashion accompanied by alcohol. The setting is
not conducive to the use of clean needles and amphetamine use is an independent risk
factor for HIV infection.
- Injecting drug user are increasingly emerging as a polydrug abusing group and as
amphetamines are cheaper than heroin on the street more IDUs are including amphetamines in
their repertoire of drug use.
The effects of amphetamines depend on a number of factors which include the dosage, the
mode of administration, the individual and the circumstances under which the drug is
taken.
Immediate effects at low doses
Effects at high doses
Long-term effects
Social problems
Tolerance and dependence
- Sensations of euphoria
- Enhanced self awareness and self confidence
- Increased visual awareness
- Heightened alertness
- Increased capacity for concentration
- Greater energy
- Users become hyperactive, talkative, excited, irritable and restless
- Reduction of appetite
- Increased breathing and heart rate
- Raised blood pressure
- Dilation of the pupils.
- Dry mouth
- Fever
- Stereotyped movements
- Sweating
- Headache
- Blurred vision
- Dizziness
- Flushing
- Pallor
- Tachycardia
- Tremor
- Loss of coordination
- Collapse
- Jaw clenching/tension
- Nausea/vomiting
- Gastrointestinal disturbances
- Insomnia
- Rapid or slurred speech
- Seizures
- Hyperthermia
- Cerebrovascular accidents can result from haemorrhagic stroke or ischaemic events
secondary to vascular occlusion
- Possibility of permanent organic brain damage in connection with psychosis associated
with chronic amphetamine abuse
- At high doses, amphetamine abusers may experience distortions and gross alterations in
body image which are often extremely frightening
- Amphetamine psychosis
- this is a paranoid psychosis with disorientation in some place or person
- amphetamine psychosis is often preceded by restlessness, irritability and increased
perceptual sensitivity
- symptoms include delusions of persecution, ideas of reference, and often bizarre visual
and auditory hallucinations
- amphetamine psychosis can often only be distinguished from paranoid schizophrenia by the
short time it takes the symptoms to disappear, usually a few days or weeks after drug use
is stopped.
- Malnutrition since amphetamines suppress appetite, illnesses related to nutrition
and vitamin deficiencies occur and there is increased susceptibility to disease
- Violence intense and sudden acts of aggression can occur. Aggressive acts are
often related to paranoia, feelings of persecution, and distortion of perception
- Multiple drug use depressant drugs such as alcohol and barbiturates may be used
in combination to combat the side effects of amphetamine use, such as sleeplessness
- Blockage of blood vessels impure amphetamines may contain particles which can
block small blood vessels and lead to kidney damage, lung emboli or stroke
- Depression often a vicious cycle exists. A patient suffering from chronic
depression takes amphetamine for relief, becomes dependent, tries to discontinue its use,
suffers depression as a withdrawal symptom, and renews amphetamine use.
- Violent aggressive behaviour
- The use of amphetamines by drivers of heavy road transport vehicles causing serious road
vehicle accidents
- Spread of HIV and other infections through the use of non-sterile injecting equipment
(sharing)
- Belief of users that amphetamines are not harmful and therefore those dependent on
amphetamines are unlikely to contact drug services
- Amphetamine use by adolescents may affect psychosexual development
- Misdiagnosis of amphetamine psychosis as paranoid schizophrenia
- Use can result in criminal activity
- When used to treat hyperkinetic children some children may show an exaggeration of
original symptoms as well as experience the side effects associated with amphetamine use.
Tolerance develops to many of the actions of amphetamines. These include euphoria,
anorexia, hyperthermia, tachycardia, hypertension and increased excretion of
noradrenaline.
Little tolerance seems to develop to the anti-sleep actions of these drugs
Psychostimulant withdrawal is generally described in three phases crash,
withdrawal and extinction. The characteristics of these phases are as follows:
- Crash the initial period which classically follows a 'run' of use. The most
common effects experienced include fatigue and exhaustion. Effects may last several hours
to several days.
- Withdrawal this phase may last for a number of weeks or even months and is
typically characterised by:
- lethargy/fatigue
- long but disturbed sleep
- irritability
- strong hunger
- deep depression that may lead to attempted suicide
- fits of violent action
- anxiety attacks
- psychic disruption and loss of self-control which may result in aggression
- headaches
- trouble breathing
- sweating
- muscle cramps
- gastrointestinal cramps
- severe secondary reactions ie influenza, pneumonia.
- Extinction normal mood and behaviour is interrupted by episodic craving often in
response to conditioned cues. These cravings may last minutes or hours and may continue to
occur months or years after cessation of amphetamine use.
The most florid symptoms
usually dissipate within a few days or weeks of cessation of use of amphetamines. Often, a
significant improvement in mood, energy, and paranoid thinking occurs within days.
Other symptoms such as normal sleep patterns, memory loss, confusion and paranoid
thinking and perceptual abnormalities may persist for perhaps six to twelve months.
After that time, residual symptoms, if present, are generally slight and not disabling,
and are noticed primarily by the user.
Abstinence is probably the most important therapeutic device, however, some crises may
yield to phenothiazine tranquillisers as first aid despite its risk of lowering seizure
threshold. Currently there is a trend for using tricyclic antidepressants as part of the
management of psychostimulant dependence.
|