Amphetamine

• 1. Introduction

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  Amphetamine is a central nervous system stimulant with a history stretching back to 1887, when Romanian chemist Lazăr Edeleanu first synthesized it in Germany and named it phenylisopropylamine. For nearly four decades, the molecule sat largely unexamined. Then, in 1927, Gordon Alles independently resynthesized it and reported its sympathomimetic properties, setting in motion one of the most consequential pharmaceutical stories of the twentieth century.

  By the mid-1930s, Smith, Kline and French were selling it over the counter as an inhaler called Benzedrine, marketed as a decongestant. Within years it was being prescribed for narcolepsy, obesity, low blood pressure, depression, and chronic pain. During World War II, both Allied and Axis forces distributed it widely to soldiers who needed to stay alert and push through exhaustion. Decades later, it became the backbone of some of the most prescribed medications in the world, including Adderall and Vyvanse.

  Today amphetamine occupies a strange dual position: a tightly regulated schedule II controlled substance in the United States, and a drug used daily by millions of people for legitimate medical reasons. How does a single molecule treat attention deficits in children, suppress compulsive binge eating, and keep narcolepsy patients awake, while also carrying real risks of addiction and psychosis at high doses? The answers lie deep inside the brain's monoamine systems, in the politics of postwar drug regulation, and in decades of clinical research that have only recently begun to clarify amphetamine's full profile.

• 2. A Drug Goes to War

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  Late 1933 marked amphetamine's entry into commerce, when Smith, Kline and French launched Benzedrine as a nasal inhaler. Three years on, Benzedrine sulfate tablets appeared, prescribed for a striking range of conditions: narcolepsy, obesity, low blood pressure, low libido, and chronic pain. The molecule's stimulant properties were commercially useful almost immediately.

  World War II turned a pharmaceutical curiosity into a mass-issued compound. Both Allied and Axis forces distributed amphetamine and methamphetamine extensively, relying on their performance-enhancing and fatigue-suppressing effects to keep soldiers functional under extreme conditions. The scale of that wartime use made the drug's addictive potential undeniable, and governments moved to restrict it in the postwar decades. In the United States, the early 1970s brought amphetamine under the Controlled Substances Act as a schedule II drug. The United Nations 1971 Convention on Psychotropic Substances extended schedule II status across all 183 state parties to that treaty.

  Even as official controls tightened, amphetamine continued circulating through popular culture. A notable strand of British 1960s mod subculture centered on recreational amphetamine use, with all-night dancing at clubs like Manchester's Twisted Wheel fueled by the drug. Newspaper reports from that period described dancers leaving clubs at 5 a.m. with dilated pupils. Researcher Andrew Wilson argues that for a significant minority of mods, amphetamines symbolized a "smart, on-the-ball, cool image" and that they sought "stimulation not intoxication" and "greater awareness, not escape." That distinction, between the controlled alertness users sought and the intoxication they rejected, would resurface in debates about therapeutic versus recreational use for the rest of the century.

• 3. ADHD and the Therapeutic Case

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  Approximately 80% of people with ADHD who use stimulant medications see improvements in their symptoms, a figure drawn from clinical research on drugs that include amphetamine and methylphenidate. That figure is striking, but what the research has built up around it is more striking still.

  Models of ADHD point to functional impairments in dopamine neurotransmission along the mesocorticolimbic projection and in norepinephrine signaling from the locus coeruleus to the prefrontal cortex. Stimulants address those impairments directly by increasing neurotransmitter activity in both systems. Reviews of magnetic resonance imaging studies suggest that long-term amphetamine treatment at therapeutic doses can actually decrease abnormalities in brain structure and function found in people with ADHD, improving areas such as the right caudate nucleus of the basal ganglia.

  A nine-month randomized controlled trial of amphetamine treatment in children found an average IQ increase of 4.5 points, along with continued improvements in attention and reductions in hyperactivity and disruptive behavior. A 2024 meta-analytic systematic review reported moderate improvements in quality of life when amphetamine treatment is used for ADHD. A 2025 review of 113 randomized controlled trials found stimulant medications to be the only intervention with robust short-term efficacy for ADHD, and associated with lower all-cause treatment discontinuation rates than non-stimulants such as atomoxetine.

  Long-term studies suggest the benefits extend across many life domains. Reviews covering 9 categories of outcomes found improvements in academics, antisocial behavior, driving, non-medicinal drug use, obesity, occupation, self-esteem, service use, and social function. Perhaps most surprising to many people is the finding, from lifetime follow-up studies, that stimulant therapy beginning in childhood reduces the risk of developing a substance use disorder as an adult.

• 4. Binge Eating and the Lisdexamfetamine Pivot

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  As of July 2024, lisdexamfetamine is the only medication approved by both the US Food and Drug Administration and Australia's Therapeutic Goods Administration for the treatment of binge eating disorder. That singular status reflects both the novelty of the approval and the specificity of the mechanism researchers believe underlies it.

  Binge eating disorder involves recurrent compulsive eating episodes accompanied by marked distress and a felt loss of control. Researchers believe the disorder involves dysfunctional dopaminergic reward circuitry along the cortico-striatal-thalamic-cortical loop, and there is a proposed psychopathological overlap with ADHD, with both conditions involving deficits in cognitive control. Lisdexamfetamine is a prodrug: it is structurally inactive until the body converts it into dextroamphetamine, which then increases dopaminergic and noradrenergic signaling in the prefrontal cortex, the brain region responsible for regulating behavioral control.

  Three medical reviews conclude that lisdexamfetamine's enhancement of cognitive control is the primary therapeutic mechanism for reducing binge-eating symptoms, not mere appetite suppression. That conclusion is supported by the failure of anti-obesity drugs and other appetite suppressants to significantly reduce binge eating disorder symptom severity, despite being able to produce weight loss. Medical reviews of randomized controlled trials show that lisdexamfetamine at doses between 50-70 mg is safe and effective for moderate-to-severe binge eating disorder in adults, producing significant reductions in the number of binge eating days and episodes per week. An open-label 12-month extension study found the drug remained effective at reducing binge eating days for its full duration.

• 5. How the Brain Changes

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  Amphetamine enters axon terminals through monoamine transporters, including the dopamine transporter (DAT), the norepinephrine transporter (NET), and the serotonin transporter (SERT), or by diffusing directly across neuronal membranes. Once inside the cell, it triggers a cascade of molecular events that ultimately flood the synaptic cleft with dopamine and norepinephrine.

  The mechanism involves phosphorylation: protein kinases such as PKA, PKC, CaMKII, and RhoA attach phosphate groups to specific amino acid residues on monoamine transporters, shifting those transporters into a state that pumps monoamines outward rather than inward. Amphetamine also disrupts the storage of dopamine inside synaptic vesicles. It collapses the vesicular pH gradient maintained by VMAT2, releasing dopamine from vesicles into the neuronal cytosol, where the reversed transporters can push it into the synapse. The compound TAAR1, a G-protein coupled receptor discovered in 2001, has been identified as a key molecular target linking amphetamine to these transporter effects.

  At higher doses and with chronic use, those same mechanisms become pathological. Repeated high-dose exposure drives sustained overexpression of a protein called ΔFosB in the nucleus accumbens. ΔFosB acts as a molecular switch, and once it accumulates sufficiently in D1-type medium spiny neurons, it begins to drive compulsive drug-seeking that intensifies with further expression. The same protein is implicated in addictions to a broad range of substances, including alcohol, cocaine, nicotine, opioids, and methamphetamine. Critically, gene regulation studies using doses and routes equivalent to human therapeutic use show that these changes, if they occur at all at therapeutic levels, are relatively minor.

• 6. Addiction, Exercise, and Recovery

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  Addiction is a serious risk with heavy recreational amphetamine use, involving doses far above the therapeutic range. At those levels, drug tolerance develops rapidly, so users require progressively larger amounts to achieve the same effect. A Cochrane review on withdrawal in chronic heavy users found that symptoms occur in roughly 88% of cases within 24 hours of stopping the drug, persist for 3-4 weeks, and include a marked "crash" in the first week. Symptoms can include anxiety, drug craving, depressed mood, fatigue, increased appetite, sleeplessness or excessive sleeping, and lucid dreams. The severity correlates with the individual's age and the extent of their dependence.

  There is currently no effective pharmacotherapy for amphetamine addiction. A 2019 systematic review and meta-analysis assessed 17 different medications tested in randomized controlled trials and found only low-strength evidence that methylphenidate might reduce amphetamine self-administration. Most other medications showed low to moderate evidence of no benefit.

  Aerobic exercise stands out from that list as an exception with genuine supporting evidence. Research suggests that daily aerobic exercise, particularly endurance activities like marathon running, both reduces the risk of developing addiction and serves as an effective adjunct therapy alongside behavioral treatments. Mechanically, aerobic exercise decreases psychostimulant self-administration, reduces relapse rates, and increases the density of dopamine receptor D2 in the striatum. That last effect is directly opposite to what pathological stimulant use does: heavy amphetamine use decreases striatal DRD2 density. The most effective behavioral combination identified in a 2018 network meta-analysis of 50 trials was contingency management paired with community reinforcement approach, which produced the highest abstinence rates and lowest dropout rates among 12 psychosocial interventions studied.

• 7. The Chemical Landscape

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  Amphetamine belongs to the phenethylamine class and is also the parent compound of its own structural class, the substituted amphetamines, which includes bupropion, cathinone, MDMA, and methamphetamine. Understanding what amphetamine shares with, and how it differs from, compounds produced naturally in the human body is central to understanding why it has the effects it does.

  Phenethylamine, the parent compound of amphetamine, is produced inside the human body from L-phenylalanine by the same enzyme that converts L-DOPA into dopamine. A positional isomer called N-methylphenethylamine is metabolized from phenethylamine by the same enzyme that converts norepinephrine into epinephrine. Both of these endogenous compounds regulate monoamine neurotransmission through the same TAAR1 receptor that amphetamine activates. The difference is persistence: phenethylamine and N-methylphenethylamine are rapidly broken down by monoamine oxidase B, giving them far shorter half-lives than amphetamine.

  The two mirror-image forms of amphetamine, levoamphetamine and dextroamphetamine, behave differently in the brain. Dextroamphetamine binds the dopamine transporter more strongly than its counterpart, producing roughly three to four times more stimulation, and is the enantiomer responsible for most of the drug's rewarding and wakefulness-promoting properties. Levoamphetamine, meanwhile, has slightly stronger cardiovascular and peripheral effects. At normal urine pH, the half-lives of dextroamphetamine and levoamphetamine are 9-11 hours and 11-14 hours, respectively. Highly alkaline urine can extend those half-lives up to 34 hours. Dextroamphetamine sulfate, sold under the brand name Dexedrine since 1976, remains the only enantiopure amphetamine product currently available in the United States.