What is methamphetamine?
Methamphetamine is a powerful, highly addictive stimulant that affects the central nervous system. Also known as meth, chalk, ice and crystal, among many other terms, it is a white, odourless, bitter-tasting crystalline powder that dissolves easily in water or alcohol.
Development of methamphetamine
Methamphetamine was developed early in the 20th century from its parent drug, amphetamine, and was originally used in nasal decongestants and bronchial inhalers. Like amphetamine, methamphetamine causes increased activity and talkativeness, decreased appetite, and a pleasurable sense of wellbeing or euphoria.
Methamphetamine is a man-made stimulant and a more potent form of amphetamine. It was first synthesised from ephedrine in 1918. In 1935, a study of the effects of amphetamine in hospital workers found that the most commonly reported effects were a sense of wellbeing and exhilaration, and reduced fatigue. During World War II, amphetamine was used extensively to combat fatigue and increase alertness in soldiers.
Methamphetamine today
Today, amphetamines and amphetamine derivatives are used in the treatment of narcolepsy (a sleep disorder) and attention deficit hyperactivity disorder (ADHD).
Methamphetamine differs from amphetamine in that, at comparable doses, much greater amounts of the drug reach the brain, making it a more potent stimulant. It also has longer-lasting and more harmful effects on the central nervous system. These characteristics give it a high potential for widespread abuse.
The U.S. Drug Enforcement Administration has classified methamphetamine as a Schedule II stimulant, which makes it legally available only through a nonrefillable prescription. Medically it may be indicated for the treatment of ADHD and as a short-term component of weight-loss treatments, but these uses are limited and it is rarely prescribed. The prescribed doses are also far lower than those typically abused.
There are different forms of methamphetamine, generally distinguished by their appearance and perceived purity. The three main forms are:
- crystalline (ice or crystal)
- powder (speed)
- base.
Crystalline methamphetamine (ice) is a highly purified form with a crystal-like appearance. The only difference between ice and the other forms, speed and base, is that ice undergoes additional refinement to remove impurities. Ecstasy, which is sold as a tablet, is also a methamphetamine derivative.
How methamphetamine is abused
Methamphetamine is taken orally, smoked, snorted, or dissolved in water or alcohol and injected. Smoking or injecting the drug delivers it very quickly to the brain, where it produces an immediate, intense euphoria. Because the pleasure also fades quickly, users often take repeated doses in a ‘binge and crash’ pattern.
People who use methamphetamine long term may experience anxiety, confusion, insomnia and mood disturbances, and may display violent behaviour. They may also show symptoms of psychosis, such as paranoia, visual and auditory hallucinations, and delusions (for example, the sensation of insects crawling under the skin).
Chronic methamphetamine use is accompanied by chemical and molecular changes in the brain. Imaging studies have shown changes in the activity of the dopamine system that are associated with reduced motor skills and impaired verbal learning. In studies of chronic users, severe structural and functional changes have been found in areas of the brain associated with emotion and memory, which may account for many of the emotional and cognitive problems seen in these people.