Substance Misuse - Managing amphetamine use

GPs should be aware of illegal stimulants and the best ways to help users, says Dr Gordon Morse.

Cardiac arrthythmias are a common effect of amphetamine use (photograph: spl)
Cardiac arrthythmias are a common effect of amphetamine use (photograph: spl)

Humans have exploited chemicals to counteract negative feelings for centuries and developed the ability to make psychoactive drugs de novo.

Amphetamine sulphate and methamphetamine were formulated in 1930, and were recognised as powerful stimulants that elevated energy and mood.

The pharmaceutical industry promoted these drugs for the treatment of obesity, seizures, depression and schizophrenia.

As the harms of these powerful stimulants became apparent their medicinal use declined, but now amphetamines are some of the most widely misused drugs in the world.

Commonly known as 'whizz', amphetamine sulphate is usually sold as a putty-like substance, the purity varying from a few per cent to 30 per cent. It may be swallowed, snorted or injected.

Methamphetamine is known as crystal meth or ice, and is smoked or injected. There has been much made of a potential epidemic of methamphetamine use in the UK, but reports of use have been few so far.

This may be because cocaine and amphetamines are so readily available that the UK stimulant market is saturated with their use.

Effects and dangers
Amphetamines increase exercise tolerance, wakefulness, concentration, libido and mood, and it is understandable why these drugs are so widely misused.

The number of users who become dependent is low. Most use amphetamines as they might alcohol, but for some it is a highly damaging obsession.

Methamphetamine is a slightly longer acting drug than amphetamine sulphate and has a higher bioavailability, but the risks and harms of the two drugs are broadly similar.

Anorexia, insomnia, irritability and anxiety are common with infrequent use, and resolve promptly when use is stopped.

Muscle aches and tooth grinding are reported. Tolerance develops with regular use so larger amounts are consumed, sometimes several grams a day. Even allowing for some impurity, this is a huge amount of stimulation to the cardiovascular and neurological systems.

Cardiac arrhythmias are common, and there are increased risks of cardiomyopathy, MI and cerebral haemorrhage, particularly as age increases.

Depression and more serious psychotic illnesses are often associated with heavy use, especially when injected.

Injecting attracts all the associated harms of this practice, and as doses may be repeated many times a day in an atmosphere of increasing chaos, the risks of blood-borne virus transmission and damage to veins are high.

Heavy stimulant users are also likely to be co-dependent on sedative drugs such as alcohol, benzodiazepines and heroin to counteract over-stimulation and assist sleep.

Regular use of amphetamine leads to unpleasant withdrawal symptoms, characterised by lethargy and sleep, followed by a variable period of depression, which may be profound and associated with severe cravings.

Withdrawal symptoms are rarely severe; the reason most users give for relapse is to get back to what they describe as their 'normal' state.

Treatment
Treatment of amphetamine misuse relies on advice, motivational work, support and addressing coexisting social, physical and psychological harms.

Medication does not have a convincing evidence base of benefit, and the lack of availability in the UK of a long-acting stimulant as a substitute is frustrating.

Treatment of post-withdrawal depression also has a disappointing lack of evidence of benefit, although theoretically a noradrenaline reuptake inhibitor such as reboxitine should be useful.

Common problems
Insomnia is a common problem with amphetamine use, and many users look to alcohol or other sedatives to bring them down and aid sleep.

Users often ask their GP to prescribe hypnotics. Such requests should be resisted - sedation enables higher doses of amphetamines to be consumed.

Users may also present with palpitations, and a range of tachyarrhythmias with or without hypertension can occur. As they are direct consequences of amphetamine use, prescribing for them is not indicated. The arrhythmias should settle as misuse is reduced and stopped.

Cardiovascular events and MI also occur due to chronic amphetamine use. If amphetamine use persists, patients should be considered at high risk of cardiovascular disease and monitored and treated accordingly.

In common with most drug problems, adding other drugs, even if aimed at helping collateral harm, can create additional and unforeseen complications.

GPs should always be reluctant to prescribe and, if in doubt, seek specialist advice.

  • Dr Morse is a GP and clinical lead for Somerset Drug and Alcohol Service

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