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.
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.