Dextroamphetamine
Dextroamphetamine is a central nervous system stimulant and enantiomer of amphetamine that is used in the treatment of attention deficit hyperactivity disorder and narcolepsy. It is also used illicitly to enhance cognitive and athletic performance, and recreationally as an aphrodisiac and euphoriant. Dextroamphetamine is generally regarded as the prototypical stimulant.
The amphetamine molecule exists as two enantiomers, levoamphetamine and dextroamphetamine. Dextroamphetamine is the dextrorotatory, or 'right-handed', enantiomer and exhibits more pronounced effects on the central nervous system than levoamphetamine. Pharmaceutical dextroamphetamine sulfate is available as both a brand name and generic drug in a variety of dosage forms. Dextroamphetamine is sometimes prescribed as the inactive prodrug lisdexamfetamine.
Side effects of dextroamphetamine at therapeutic doses include elevated mood, decreased appetite, dry mouth, excessive grinding of the teeth, headache, increased heart rate, increased wakefulness or insomnia, anxiety, and irritability, among others. At excessive doses, psychosis, addiction, and rapid muscle breakdown may occur. However, for individuals with pre-existing psychotic disorders, there may be a risk of psychosis even at therapeutic doses.
Dextroamphetamine, like other amphetamines, elicits its stimulating effects via several distinct actions: it inhibits or reverses the transporter proteins for the monoamine neurotransmitters either via trace amine-associated receptor 1 or in a TAAR1 independent fashion when there are high cytosolic concentrations of the monoamine neurotransmitters and it releases these neurotransmitters from synaptic vesicles via vesicular monoamine transporter 2. It also shares many chemical and pharmacological properties with human trace amines, particularly phenethylamine and, the latter being an isomer of amphetamine produced within the human body. It is available as a generic medication. In 2022, mixed amphetamine salts was the 14th most commonly prescribed medication in the United States, with more than 34million prescriptions.
Uses
Medical
Dextroamphetamine is used to treat attention deficit hyperactivity disorder and narcolepsy, and is sometimes prescribed for depression and obesity.ADHD
Narcolepsy
Enhancing performance
Recreational
Dextroamphetamine is also used recreationally as a euphoriant and aphrodisiac, and, like other amphetamines, is used as a club drug for its energetic and euphoric high. Dextroamphetamine is considered to have a high potential for misuse in a recreational manner since individuals typically report feeling euphoric, more alert, and more energetic after taking the drug. Dextroamphetamine's dopaminergic properties affect the mesocorticolimbic circuit; a group of neural structures responsible for incentive salience, positive reinforcement and positively-valenced emotions, particularly ones involving pleasure. Large recreational doses of dextroamphetamine may produce [|dextroamphetamine overdose]. Recreational users sometimes open dexedrine capsules and crush the contents in order to insufflate it or subsequently dissolve it in water and inject it. Immediate-release formulations have higher potential for abuse via insufflation or intravenous injection due to a more favorable pharmacokinetic profile and easy crushability.The reason for using crushed spansules for insufflation and injection methods is evidently due to the instant-release forms of the drug seen in tablet preparations often containing a sizable amount of inactive binders and fillers alongside the active d-amphetamine, such as dextrose. Injection into the bloodstream can be dangerous because insoluble fillers within the tablets can block small blood vessels. Chronic overuse of dextroamphetamine can lead to severe drug dependence, resulting in withdrawal symptoms when drug use stops.
Contraindications
Adverse effects
Overdose
Interactions
Many types of substances are known to interact with amphetamine, resulting in altered drug action or metabolism of amphetamine, the interacting substance, or both. Inhibitors of the enzymes that metabolize amphetamine will prolong its elimination half-life, meaning that its effects will last longer. Amphetamine also interacts with, particularly monoamine oxidase A inhibitors, since both MAOIs and amphetamine increase plasma catecholamines ; therefore, concurrent use of both is dangerous. Amphetamine modulates the activity of most psychoactive drugs. In particular, amphetamine may decrease the effects of sedatives and depressants and increase the effects of stimulants and antidepressants. Amphetamine may also decrease the effects of antihypertensives and antipsychotics due to its effects on blood pressure and dopamine respectively. Zinc supplementation may reduce the minimum effective dose of amphetamine when it is used for the treatment of ADHD. Norepinephrine reuptake inhibitors like atomoxetine prevent norepinephrine release induced by amphetamines and have been found to reduce the stimulant, euphoriant, and sympathomimetic effects of dextroamphetamine in humans.Pharmacology
Pharmacodynamics
Amphetamine and its enantiomers have been identified as potent full agonists of trace amine-associated receptor 1, a GPCR, discovered in 2001, that is important for regulation of monoaminergic systems in the brain. Activation of TAAR1 increases cAMP production via adenylyl cyclase activation and inhibits the function of the dopamine transporter, norepinephrine transporter, and serotonin transporter, as well as inducing the release of these monoamine neurotransmitters. Amphetamine enantiomers are also substrates for a specific neuronal synaptic vesicle uptake transporter called VMAT2. When amphetamine is taken up by VMAT2, the vesicle releases dopamine, norepinephrine, and serotonin, among other monoamines, into the cytosol in exchange.Dextroamphetamine and levoamphetamine have identical pharmacodynamics, but their binding affinities to their biomolecular targets vary. Dextroamphetamine is a more potent agonist of TAAR1 than levoamphetamine. Consequently, dextroamphetamine produces roughly three to four times more central nervous system stimulation than levoamphetamine; however, levoamphetamine has slightly greater cardiovascular and peripheral effects.
Related endogenous compounds
Pharmacokinetics
History, society, and culture
amphetamine was first synthesized under the chemical name "phenylisopropylamine" in Berlin, 1887 by the Romanian chemist Lazăr Edeleanu. It was not widely marketed until 1932, when the pharmaceutical company Smith, Kline & French introduced it in the form of the Benzedrine inhaler for use as a bronchodilator. Notably, the amphetamine contained in the Benzedrine inhaler was the liquid free-base, not a chloride or sulfate salt.In 1935, the medical community became aware of the stimulant properties of amphetamine, specifically the dextroamphetamine isomer, and in 1937 Smith, Kline, and French introduced tablets under the brand name Dexedrine. In the United States, Dexedrine was approved to treat narcolepsy and attention deficit hyperactivity disorder. In Canada indications once included epilepsy and parkinsonism. Dextroamphetamine was marketed in various other forms in the following decades, primarily by Smith, Kline, and French, such as several combination medications including a mixture of dextroamphetamine and amobarbital sold under the brand name Dexamyl and, in the 1950s, an extended release capsule. Preparations containing dextroamphetamine were also used in World War II as a treatment against fatigue.
It quickly became apparent that dextroamphetamine and other amphetamines had a high potential for misuse, although they were not heavily controlled until 1970, when the Comprehensive Drug Abuse Prevention and Control Act was passed by the United States Congress. Dextroamphetamine, along with other sympathomimetics, was eventually classified as Schedule II, the most restrictive category possible for a drug with a government-sanctioned, recognized medical use. Internationally, it has been available under the names AmfeDyn, Curban, Obetrol, Simpamina, Dexedrine/GSK, Dexedrine/UCB, Dextropa, and Stild. It became popular on the mod scene in England in the early 1960s, and carried through to the Northern Soul scene in the north of England to the end of the 1970s.
In October 2010, GlaxoSmithKline sold the rights for Dexedrine Spansule to Amedra Pharmaceuticals.
The U.S. Air Force uses dextroamphetamine as one of its "go pills", given to pilots on long missions to help them remain focused and alert. Conversely, "no-go pills" are used after the mission is completed, to combat the effects of the mission and "go-pills". The Tarnak Farm incident was linked by media reports to the use of this drug on long term fatigued pilots. The military did not accept this explanation, citing the lack of similar incidents. Newer stimulant medications or awakeness promoting agents with different side effect profiles, such as modafinil, are being investigated and sometimes issued for this reason.
Formulations
| Brand name | United States Adopted Name | ratio | Dosage form | Marketing start date | Sources |
| Adderall | Mixed amphetamine salts | 3:1 | tablet | 1996 | |
| Adderall XR | Mixed amphetamine salts | 3:1 | capsule | 2001 | |
| Mydayis | Mixed amphetamine salts | 3:1 | capsule | 2017 | |
| Adzenys XR-ODT | amphetamine | 3:1 | ODT | 2016 | |
| Dyanavel XR | amphetamine | 3.2:1 | suspension | 2015 | |
| Evekeo | amphetamine sulfate | 1:1 | tablet | 2012 | |
| Dexedrine | dextroamphetamine sulfate | 1:0 | capsule | 1976 | |
| Zenzedi | dextroamphetamine sulfate | 1:0 | tablet | 2013 | |
| Vyvanse | lisdexamfetamine dimesylate | 1:0 | capsule | 2007 | |
| Vyvanse | lisdexamfetamine dimesylate | 1:0 | tablet | 2007 | |
| Xelstrym | dextroamphetamine | 1:0 | patch | 2022 |