Amphetamine

Amphetamine is a potent central nervous system (CNS) stimulant of the phenethylamine class that is primarily prescribed for the medical treatment of attention deficit hyperactivity disorder (ADHD) and narcolepsy, while also carrying a significant risk of recreational abuse and psychological dependence.

Chemistry and Pharmacology

Amphetamine, chemically known as alpha-methylphenethylamine, is a synthetic compound that exists as two enantiomers: dextroamphetamine and levoamphetamine. The racemic mixture contains equal parts of both, though dextroamphetamine possesses significantly stronger CNS stimulant effects, whereas levoamphetamine has more pronounced peripheral cardiovascular effects. Pharmacologically, amphetamine acts primarily as a releasing agent and reuptake inhibitor of the monoamine neurotransmitters dopamine, norepinephrine, and serotonin. It enters the presynaptic neuron primarily via the plasma membrane monoamine transporters or by diffusion, where it forces the reversal of these transporters and displaces neurotransmitters from vesicular storage via the vesicular monoamine transporter 2 (VMAT2). This mechanism results in a massive efflux of monoamines into the synaptic cleft, leading to the characteristic stimulant effects of increased alertness, elevated mood, and enhanced physical and cognitive performance.

Medical Uses

In modern clinical practice, amphetamine and its derivatives are primarily utilized as a first-line treatment for attention deficit hyperactivity disorder (ADHD). By increasing dopamine and norepinephrine levels in the prefrontal cortex, the drug improves executive function, sustained attention, and impulse control in affected individuals. It is also a standard treatment for narcolepsy, a chronic sleep disorder characterized by excessive daytime sleepiness and sudden sleep attacks, as the stimulant properties promote prolonged wakefulness. Historically, amphetamine was widely prescribed as an anorectic agent for the short-term treatment of obesity due to its appetite-suppressing effects, though this use has declined significantly due to the availability of safer alternatives and the high potential for abuse. Other off-label or historical uses have included the treatment of treatment-resistant depression and chronic fatigue, though these are rarely indicated today.

Recreational Use and Abuse

Due to its ability to induce euphoria, increase energy, and enhance sociability, amphetamine is frequently diverted for non-medical use. Recreational users often take the drug to experience a "rush" or "high," to stay awake for extended periods, or to enhance physical and cognitive performance in academic or occupational settings. It is also used as a club drug in nightlife settings and as an aphrodisiac. However, the repeated use of amphetamine for recreational purposes rapidly leads to tolerance, requiring higher doses to achieve the same effects. This pattern of use significantly increases the risk of developing a substance use disorder, characterized by compulsive drug-seeking behavior and loss of control over intake.

Adverse Effects and Toxicity

The adverse effects of amphetamine are dose-dependent and can range from mild to life-threatening. Physical side effects include tachycardia, hypertension, hyperthermia, dry mouth, insomnia, and gastrointestinal disturbances. At high doses or with chronic abuse, the cardiovascular strain can lead to arrhythmias, myocardial infarction, or stroke. Psychiatric adverse effects are equally concerning and include anxiety, agitation, irritability, and panic attacks. Severe intoxication or prolonged bingeing can precipitate amphetamine psychosis, a condition characterized by paranoia, visual and auditory hallucinations, and delusions, which closely resembles paranoid schizophrenia. Upon cessation of chronic use, individuals typically experience a withdrawal syndrome marked by severe fatigue, hypersomnia, increased appetite, vivid unpleasant dreams, and profound depression, which can sometimes lead to suicidal ideation.

History

Amphetamine was first synthesized in 1887 by the Romanian chemist Lazăr Edeleanu in Germany, but its pharmacological properties were not fully explored until the late 1920s. In 1930, Smith, Kline & French introduced the Benzedrine inhaler as a decongestant, and its stimulating side effects quickly led to its widespread medical and recreational use. During World War II, amphetamine was extensively used by military personnel on both sides of the conflict to combat fatigue and maintain alertness during prolonged missions. In the post-war era, the drug became highly popular in civilian society for weight loss and mood enhancement, leading to a surge in abuse and addiction. Consequently, governments began to tighten regulations in the 1960s and 1970s, restricting medical prescriptions and shifting the focus toward safer, longer-acting formulations for specific psychiatric conditions.

Legal Status

Due to its high potential for abuse and dependence, amphetamine is strictly regulated globally. Under the United Nations Convention on Psychotropic Substances of 1971, it is classified as a Schedule II substance, indicating that it has a high potential for abuse but also possesses accepted medical uses with severe restrictions. In the United States, the Drug Enforcement Administration (DEA) classifies amphetamine as a Schedule II controlled substance under the Controlled Substances Act, meaning it can only be dispensed with a written prescription that cannot be refilled without a new evaluation by a healthcare provider. Similar stringent scheduling and prescription monitoring programs are in place in most other countries to prevent diversion and illicit use.