More commonly known by the street names speed, ice or crystal meth, both amphetamine and methamphetamine belong to a group of stimulant drugs called amphetamines.
Australia has one of the highest rates of illicit methamphetamine use in the world and the highest use among English-speaking countries. Around 2.5% of Australians over 14 years – around half a million people – have used methamphetamine in the last year. This rate is three-to five-times higher than the USA, Canada (0.5%) or the UK (1%).
But what exactly is methamphetamine? And if so many Australians are using it, how is addiction or dependence treated?
Amphetamine was first synthesised in the late 1800s. No medical use was found until the late 1920s, after which amphetamines became widely available as an over-the-counter drug in the form of an inhaler, much like a ventolin inhaler is today.
Methamphetamine was first synthesised shortly after amphetamine in the late 1890s and was approved for use in the United States and other countries at the end of the second world war for treatment of a wide range of problems including narcolepsy, mild depression, chronic alcoholism and hay fever.
Both amphetamine and methamphetamine were used extensively in the second world war by both allied and axis forces to prevent fatigue in their combat troops.
The release of the war stockpile created the first amphetamine epidemic in the 1950s. Civilian users of both drugs began to see the recreational potential and the rise in use around the world caused many countries to ban or restrict production.
Today, amphetamines are prescription-only medicines used to treat attention deficit and hyperactivity disorder (ADHD) and narcolepsy (a sleep disorder), and sometimes depression and obesity.
Occasionally, prescription amphetamines such as dexamphetamine are also diverted to the illicit market.
The illegal manufacture of street amphetamines in Australia is almost exclusively methamphetamine.
Illicit methamphetamine is manufactured in local “meth labs” and also imported from South-East Asia.
The drug usually comes in powder or pills (speed) or crystalline (ice) forms. Although both can be used in many ways, speed is usually swallowed or snorted and ice is usually smoked or injected.
Methamphetamine in small to moderate doses increases energy and wakefulness, self-esteem and sociability and sexual arousal, and reduces appetite and lowers inhibitions.
Large quantities can result in paranoia and hallucinations, and a range of physical effects such as chest pain, dangerously high body temperature, muscle spasm, brain haemorrhage, heart attack and seizures.
How it works
Methamphetamine increases the level of dopamine, the brain’s natural pleasure chemical, to ten times its normal levels. Very little else can increase dopamine like methamphetamine.
Over time, the brain stops being able to produce enough dopamine on its own. It then needs more and more to get the same high (tolerance).
When a person stops using methamphetamine, they may start to feel depressed because their dopamine system has been worn out from over-producing dopamine. This is part of the withdrawal process when the brain misses having the drug in its system. Symptoms of methamphetamine withdrawal include intense craving, anxiety, flat mood, decreased energy and motivation, and problems sleeping.
Currently, the main treatment for methamphetamine dependence is cognitive behaviour therapy (CBT). The main premise of CBT is that unhelpful thinking drives feelings and behaviour.
A methamphetamine user who has quit, for example, might think, “I can’t cope with these cravings,” and go back to using. CBT would teach them to identify and modify those thoughts that lead to relapse. A new thought might be, “these cravings are hard, but if I wait the feeling will go away.”
However, methamphetamine users are often reluctant to seek treatment. The lack of an effective pharmaceutical therapy is considered a significant barrier to getting methamphetamine users into treatment.
The search for a medicine to treat methamphetamine dependence has been ongoing for the best part of two decades. More than 18 different medicines have been trialled but none have been approved for methamphetamine treatment. While some of these medicines have shown some effects for some users, none have shown a big enough or widespread enough effect to be considered broadly useful.
One of the difficulties in finding an effective medicine is that methamphetamine can have a very complex action in the brain, affecting (and damaging) many systems, including reward pathways and multiple systems that control thinking, memory, attention and mood.
Now the US Food and Drug Administration has reportedly fast-tracked human tests of a potential new treatment after UCLA researchers conducted tests that showed that this new medicine is safe for people who use methamphetamine, and seemed to reduce craving and improve brain functioning.
The new medicine, ibudilast, is an anti-inflammatory substance that is used to treat asthma and stroke in Japan, and is thought to reduce reward from the activation of the dopamine system.
But the current UCLA ibudilast trial is still in the early stages of development. Further investigations are still needed to see whether the medicine helps reduce or stop methamphetamine use, before it can be considered for general use.
The testing of any promising medicine is a crucial step forward for the treatment of methamphetamine dependence. Many medicines have previously looked promising and have made it through early testing, but failed to show any significant benefits for dependent amphetamine users.
Associate Professor at the National Drug Research Institute, Curtin University.