Dextrostat

デキストロアンフェタミン

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/01/23 19:41:25」(JST)

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For the racemic compound, see Amphetamine.

Dextroamphetamine

Systematic (IUPAC) name
(2S)-1-phenylpropan-2-amine
Clinical data
Trade names	Dexedrine, Dextrostat
AHFS/Drugs.com	monograph
MedlinePlus	a605027
Licence data	US Daily Med:link
Pregnancy category	AU: B3 US: C
Legal status	AU: Controlled (S8) CA: Schedule I UK: Class B US: Schedule II
Dependence liability	Physical: None Psychological: Moderate
Addiction liability	Moderate
Routes	Medical (oral) non medical (Oral, IV, IM, intranasal)
Pharmacokinetic data
Bioavailability	Oral 75–100%
Metabolism	CYP2D6, DBH, FMO3, XM-ligase, and ACGNAT
Half-life	10-12 hours
Excretion	Renal (45%); urinary pH-dependent
Identifiers
CAS number	51-64-9 Y
ATC code	N06BA02
PubChem	CID 5826
DrugBank	DB01576
ChemSpider	5621 Y
UNII	TZ47U051FI Y
KEGG	D03740 Y
ChEBI	CHEBI:4469 Y
ChEMBL	CHEMBL612 Y
Chemical data
Formula	C9H13N
Molecular mass	135.20622
SMILES C[C@@H](N)CC1=CC=CC=C1
InChI InChI=1S/C9H13N/c1-8(10)7-9-5-3-2-4-6-9/h2-6,8H,7,10H2,1H3/t8-/m0/s1 Y Key:KWTSXDURSIMDCE-QMMMGPOBSA-N Y
Physical data
Density	0.913 g/cm3
Boiling point	201.5 °C (394.7 °F)
Solubility in water	20 mg/mL (20 °C)
Y (what is this?)  (verify)

Dextroamphetamine is a potent central nervous system (CNS) stimulant and amphetamine stereoisomer prescribed for the treatment of attention deficit hyperactivity disorder (ADHD) in children and adults and the rare sleep disorder, narcolepsy. Dextroamphetamine is also widely used by military air forces as a 'go-pill' during fatigue-inducing mission profiles such as night-time bombing missions. Preparations containing dextroamphetamine were also used in World War II as a treatment against fatigue.

The amphetamine molecule has two stereoisomers: levoamphetamine and dextroamphetamine. Dextroamphetamine is the more active dextrorotatory, or "right-handed", enantiomer of the amphetamine molecule. Dextroamphetamine is available as a generic drug or under several brand names, including Dexedrine and Dextrostat. Dextroamphetamine is also the active metabolite of the prodrug lisdexamfetamine.

Dextroamphetamine, like other amphetamines, elicits its stimulating effects via two distinct actions: first, it inhibits the transporter proteins for the monoamine neurotransmitters (namely the serotonin, norepinephrine and dopamine transporters) via trace amine-associated receptor 1 (TAAR1); and second, it releases these neurotransmitters from synaptic vesicles via vesicular monoamine transporter 2. It also shares many chemical and pharmacological properties with the human trace amine neurotransmiters, especially phenethylamine and N-methylphenethylamine, the latter being an isomer of amphetamine that is produced within the human body.

Uses

Part of this section is transcluded from Amphetamine. (edit | history)

Medical

Dexedrine Spansule 5, 10 and 15 mg capsules

Dextroamphetamine is used to treat attention deficit hyperactivity disorder (ADHD) and narcolepsy (a sleep disorder), and is sometimes prescribed off-label for its past medical indications, such as depression, obesity, and nasal congestion. Long-term amphetamine exposure in some animal species is known to produce abnormal dopamine system development or nerve damage, but, in humans with ADHD, pharmaceutical amphetamines appear to improve brain development and nerve growth. Magnetic resonance imaging (MRI) studies suggest that long-term treatment with amphetamine decreases abnormalities in brain structure and function found in subjects with ADHD, and improves function in several parts of the brain, such as the right caudate nucleus of the basal ganglia.

Reviews of clinical stimulant research have established the safety and effectiveness of long-term amphetamine use for ADHD. Controlled trials spanning two years have demonstrated treatment effectiveness and safety. One review highlighted a nine-month randomized controlled trial in children with ADHD that found an average increase of 4.5 IQ points, continued increases in attention, and continued decreases in disruptive behaviors and hyperactivity.

Current models of ADHD suggest that it is associated with functional impairments in some of the brain's neurotransmitter systems; these functional impairments involve impaired dopamine neurotransmission in the mesocorticolimbic projection and norepinephrine neurotransmission in the locus coeruleus and prefrontal cortex. Psychostimulants like methylphenidate and amphetamine are effective in treating ADHD because they increase neurotransmitter activity in these systems. Approximately 70% of those who use these stimulants see improvements in ADHD symptoms. Children with ADHD who use stimulant medications generally have better relationships with peers and family members, perform better in school, are less distractible and impulsive, and have longer attention spans. The Cochrane Collaboration's review on the treatment of adult ADHD with pharmaceutical amphetamines stated that while these drugs improve short-term symptoms, they have higher discontinuation rates than non-stimulant medications due to their adverse side effects.

A Cochrane Collaboration review on the treatment of ADHD in children with tic disorders such as Tourette syndrome indicated that stimulants in general do not make tics worse, but high doses of dextroamphetamine could exacerbate tics in some individuals. Other Cochrane reviews on the use of amphetamine following stroke or acute brain injury indicated that it may improve recovery, but further research is needed to confirm this.

Performance-enhancing

Therapeutic doses of amphetamine improve cortical network efficiency, resulting in higher performance on working memory tests in all individuals. Amphetamine and other ADHD stimulants also improve task saliency (motivation to perform a task) and increase arousal (wakefulness), in turn promoting goal-directed behavior. Stimulants such as amphetamine can improve performance on difficult and boring tasks and are used by some students as a study and test-taking aid. Based upon studies of self-reported illicit stimulant use, students primarily use stimulants such as amphetamine for performance enhancement rather than abusing them as recreational drugs. However, high amphetamine doses that are above the therapeutic range can interfere with working memory and cognitive control.

Amphetamine is used by some athletes for its psychological and performance-enhancing effects, such as increased stamina and alertness; however, its use is prohibited at sporting events regulated by collegiate, national, and international anti-doping agencies. In healthy people at oral therapeutic doses, amphetamine has been shown to increase physical strength, acceleration, stamina, and endurance, while reducing reaction time. Amphetamine improves stamina, endurance, and reaction time primarily through reuptake inhibition and effluxion of dopamine in the central nervous system. At therapeutic doses, the adverse effects of amphetamine do not impede athletic performance; however, at much higher doses, amphetamine can induce effects that severely impair performance, such as rapid muscle breakdown and elevated body temperature.

Contraindications

This section is transcluded from Amphetamine. (edit | history)

According to the International Programme on Chemical Safety (IPCS) and United States Food and Drug Administration (USFDA), amphetamine is contraindicated in people with a history of drug abuse, heart disease, severe agitation, or severe anxiety. It is also contraindicated in people currently experiencing arteriosclerosis (hardening of the arteries), glaucoma (increased eye pressure), hyperthyroidism (excessive production of thyroid hormone), or hypertension. People who have experienced allergic reactions to other stimulants in the past or who are taking monoamine oxidase inhibitors (MAOIs) are advised not to take amphetamine. These agencies also state that anyone with anorexia nervosa, bipolar disorder, depression, hypertension, liver or kidney problems, mania, psychosis, Raynaud's phenomenon, seizures, thyroid problems, tics, or Tourette syndrome should monitor their symptoms while taking amphetamine. Evidence from human studies indicates that therapeutic amphetamine use does not cause developmental abnormalities in the fetus or newborns (i.e., it is not a human teratogen), but amphetamine abuse does pose risks to the fetus. Amphetamine has also been shown to pass into breast milk, so the IPCS and USFDA advise mothers to avoid breastfeeding when using it. Due to the potential for reversible growth impairments, the USFDA advises monitoring the height and weight of children and adolescents prescribed an amphetamine pharmaceutical.

Side effects

This section is transcluded from Amphetamine. (edit | history)

Physical

At normal therapeutic doses, the physical side effects of amphetamine vary widely by age and from person to person. Cardiovascular side effects can include hypertension or hypotension from a vasovagal response, Raynaud's phenomenon (reduced blood flow to extremities), and tachycardia (increased heart rate). Sexual side effects in males may include erectile dysfunction, frequent erections, or prolonged erections. Abdominal side effects may include stomach pain, loss of appetite, nausea, and weight loss. Other potential side effects include dry mouth, excessive grinding of the teeth, acne, profuse sweating, blurred vision, reduced seizure threshold, and tics (a type of movement disorder). Dangerous physical side effects are rare at typical pharmaceutical doses.

Amphetamine stimulates the medullary respiratory centers, producing faster and deeper breaths. In a normal person at therapeutic doses, this effect is usually not noticeable, but when respiration is already compromised, it may be evident. Amphetamine also induces contraction in the urinary bladder sphincter, the muscle which controls urination, which can result in difficulty urinating. This effect can be useful in treating bed wetting and loss of bladder control. The effects of amphetamine on the gastrointestinal tract are unpredictable. If intestinal activity is high, amphetamine may reduce gastrointestinal motility (the rate at which content moves through the digestive system); however, amphetamine may increase motility when the smooth muscle of the tract is relaxed. Amphetamine also has a slight analgesic effect and can enhance the pain relieving effects of opiates.

USFDA commissioned studies from 2011 indicate that in children, young adults, and adults there is no association between serious adverse cardiovascular events (sudden death, heart attack, and stroke) and the medical use of amphetamine or other ADHD stimulants.

Psychological

Common psychological effects of therapeutic doses can include increased alertness, apprehension, concentration, decreased sense of fatigue, mood swings (elated mood followed by mildly depressed mood), increased initiative, insomnia or wakefulness, self-confidence, and sociability. Less common side effects include anxiety, change in libido, grandiosity, irritability, repetitive or obsessive behaviors, and restlessness; these effects depend on the user's personality and current mental state. Amphetamine psychosis (e.g., delusions and paranoia) can occur in heavy users. Although very rare, this psychosis can also occur at therapeutic doses during long-term therapy. According to the USFDA, "there is no systematic evidence" that stimulants produce aggressive behavior or hostility.

Overdose

This section is transcluded from Amphetamine. (edit | history)

An amphetamine overdose can lead to many different symptoms, but is rarely fatal with appropriate care. The severity of overdose symptoms increases with dosage and decreases with drug tolerance to amphetamine. Tolerant individuals have been known to take as much as 5 grams of amphetamine in a day, which is roughly 100 times the maximum daily therapeutic dose. Symptoms of a moderate and extremely large overdose are listed below; fatal amphetamine poisoning usually also involves convulsions and coma.

Pathological overactivation of the mesolimbic pathway, a dopamine pathway that connects the ventral tegmental area to the nucleus accumbens, plays a central role in amphetamine addiction. Individuals who frequently overdose on amphetamine during recreational use have a high risk of developing an amphetamine addiction, since repeated overdoses gradually increase the level of accumbal ΔFosB, a "molecular switch" and "master control protein" for addiction. Once nucleus accumbens ΔFosB is sufficiently overexpressed, it begins to increase the severity of addictive behavior (e.g., compulsive drug-seeking). While there are currently no effective drugs for treating amphetamine addiction, regularly engaging in sustained aerobic exercise appears to reduce the risk of developing such an addiction. Sustained aerobic exercise on a regular basis also appears to be an effective treatment for amphetamine addiction; exercise therapy improves clinical treatment outcomes and may be used as a combination therapy with cognitive behavioral therapy, which is currently the best clinical treatment available.

Overdose symptoms by system

System	Minor or moderate overdose	Severe overdose
Cardiovascular	Abnormal heartbeat High or low blood pressure	Cardiogenic shock (heart not pumping enough blood) Cerebral hemorrhage (bleeding in the brain) Circulatory collapse (partial or complete failure of the circulatory system)
Central nervous system	Confusion Abnormally fast reflexes Severe agitation Tremor (involuntary muscle twitching)	Amphetamine psychosis (e.g., delusions and paranoia) Compulsive and repetitive behavior Serotonin syndrome (excessive serotonergic nerve activity) Sympathomimetic toxidrome (excessive adrenergic nerve activity)
Musculoskeletal	Muscle pain	Rhabdomyolysis (rapid muscle breakdown)
Respiratory	Rapid breathing	Pulmonary edema (fluid accumulation in the lungs) Pulmonary hypertension (high blood pressure in the arteries of the lung) Respiratory alkalosis (reduced blood CO2)
Urinary	Painful urination Urinary retention (inability to urinate)	No urine production Kidney failure
Other	Elevated body temperature	Elevated or low blood potassium Hyperpyrexia (extremely elevated body temperature) Metabolic acidosis (excessively acidic bodily fluids)

Addiction

Addiction glossary
• addiction – a state characterized by compulsive engagement in rewarding stimuli, despite adverse consequences
• reinforcing stimuli – stimuli that increase the probability of repeating behaviors paired with them
• rewarding stimuli – stimuli that the brain interprets as intrinsically positive or as something to be approached
• addictive drug – a drug that is both rewarding and reinforcing
• addictive behavior – a behavior that is both rewarding and reinforcing
• sensitization – an amplified response to a stimulus resulting from repeated exposure to it
• drug tolerance – the diminishing effect of a drug resulting from repeated administration at a given dose
• drug sensitization or reverse tolerance – the escalating effect of a drug resulting from repeated administration at a given dose
• drug dependence – an adaptive state associated with a withdrawal syndrome upon cessation of repeated drug intake
• physical dependence – dependence that involves persistent physical–somatic withdrawal symptoms (e.g., fatigue)
• psychological dependence – dependence that involves emotional–motivational withdrawal symptoms (e.g., dysphoria and anhedonia)

Addiction is a serious risk with heavy recreational amphetamine use but is unlikely to arise from typical medical use at therapeutic doses. Tolerance develops rapidly in amphetamine abuse (i.e., a recreational amphetamine overdose), so periods of extended use require increasingly larger doses of the drug in order to achieve the same effect.

Biomolecular mechanisms

Current models of addiction from chronic drug use involve alterations in gene expression in certain parts of the brain, particularly the nucleus accumbens. The most important transcription factors that produce these alterations are ΔFosB, cAMP response element binding protein (CREB), and nuclear factor kappa B (NFκB). ΔFosB plays a crucial role in the development of drug addictions, since its overexpression in the nucleus accumbens is necessary and sufficient for most of the behavioral and neural adaptations that arise from addiction. Once ΔFosB is sufficiently overexpressed, it induces an addictive state that becomes increasingly more severe with further increases in ΔFosB expression. It has been implicated in addictions to alcohol, cannabinoids, cocaine, nicotine, opiates, phencyclidine, and substituted amphetamines.

ΔJunD is the transcription factor which directly opposes ΔFosB. Sufficiently overexpressing ΔJunD in the nucleus accumbens with viral vectors can completely block many of the neural and behavioral alterations seen in chronic drug abuse (i.e., the alterations mediated by ΔFosB). ΔFosB also plays an important role in regulating behavioral responses to natural rewards, such as palatable food, sex, and exercise. Since both natural rewards and addictive drugs induce expression of ΔFosB (i.e., they cause the brain to produce more of it), chronic acquisition of these rewards can result in a similar pathological state of addiction. Consequently, ΔFosB is the most significant factor involved in both amphetamine addiction and amphetamine-induced sex addictions, which are compulsive sexual behaviors that result from excessive amphetamine use. These sex addictions are caused by dopamine dysregulation syndrome, an addictive disorder which has been observed in some patients taking dopaminergic drugs, like amphetamine, for an extended period.

The effects of amphetamine on gene regulation are both dose- and route-dependent. Most of the research on gene regulation and addiction is based upon animal studies with intravenous amphetamine administration at very high doses. The few studies that have used equivalent (weight-adjusted) human therapeutic doses and oral administration show that these changes, if they occur, are relatively minor. This suggests that medical use of amphetamine does not significantly affect gene regulation.

Pharmacological treatments

A Cochrane Collaboration review on amphetamine and methamphetamine addiction indicates that the current evidence on pharmacological treatments (i.e., drugs) is extremely limited. Fluoxetine and imipramine have some limited benefits but neither drug is an effective monotherapy for amphetamine addiction. A corroborating review indicated that amphetamine addiction is mediated through increased activation of dopamine receptors and co-localized NMDA receptors in the mesolimbic pathway (i.e., the nucleus accumbens). This review also noted that magnesium ions and serotonin inhibit NMDA receptors and that the magnesium ions do so by blocking the receptor's calcium channels. It also suggested that, based upon animal testing, pathological (addiction-inducing) amphetamine use significantly reduces the level of intracellular magnesium throughout the brain. Supplemental magnesium, like fluoxetine treatment, has been shown to reduce amphetamine self-administration (doses given to oneself) in both humans and lab animals.

Behavioral treatments

Cognitive behavioral therapy is currently the most effective clinical treatment for psychostimulant addiction. Additionally, research on the neurobiological effects of physical exercise suggests that daily aerobic exercise, especially endurance exercise (e.g., marathon running), prevents the development of drug addiction and is an effective adjunct (supplemental) treatment for amphetamine addiction. Exercise leads to better treatment outcomes when used as an adjunct treatment, particularly for psychostimulant addictions. In particular, aerobic exercise decreases psychostimulant self-administration, reduces the reinstatement (i.e., relapse) of drug-seeking, and induces increased dopamine receptor D₂ (DRD2) density in the striatum. This is the opposite of pathological stimulant use, which induces decreased striatal DRD2 density.

Withdrawal

According to another Cochrane Collaboration review on withdrawal in individuals who compulsively use amphetamine and methamphetamine, "when chronic heavy users abruptly discontinue amphetamine use, many report a time-limited withdrawal syndrome that occurs within 24 hours of their last dose." This review noted that withdrawal symptoms in chronic, high-dose users are frequent, occurring in up to 87.6% of cases, and persist for three to four weeks with a marked "crash" phase occurring during the first week. Amphetamine withdrawal symptoms can include anxiety, drug craving, depressed mood, fatigue, increased appetite, increased movement or decreased movement, lack of motivation, sleeplessness or sleepiness, and lucid dreams. The review indicated that withdrawal symptoms are associated with the degree of dependence, suggesting that therapeutic use would result in far milder discontinuation symptoms. Manufacturer prescribing information does not indicate the presence of withdrawal symptoms following discontinuation of amphetamine use after an extended period at therapeutic doses.

Toxicity and psychosis

See also: Stimulant psychosis

In rodents and primates, sufficiently high doses of amphetamine cause dopaminergic neurotoxicity, or damage to dopamine neurons, which is characterized by reduced transporter and receptor function. There is no evidence that amphetamine is directly neurotoxic in humans. However, large doses of amphetamine may cause indirect neurotoxicity as a result of increased oxidative stress from reactive oxygen species and autoxidation of dopamine.

A severe amphetamine overdose can result in a stimulant psychosis that may involve a variety of symptoms, such as paranoia and delusions. A Cochrane Collaboration review on treatment for amphetamine, dextroamphetamine, and methamphetamine psychosis states that about 5–15% of users fail to recover completely. According to the same review, there is at least one trial that shows antipsychotic medications effectively resolve the symptoms of acute amphetamine psychosis. Psychosis very rarely arises from therapeutic use.

Pharmacology

Pharmacodynamics

The main section for this topic is on the page Amphetamine, in the section Pharmacodynamics.

Pharmacodynamics of amphetamine enantiomers in a dopamine neuron

via AADC

Amphetamine enters the presynaptic neuron across the neuronal membrane or through DAT. Once inside, it binds to TAAR1 or enters synaptic vesicles through VMAT2. When amphetamine enters the synaptic vesicles through VMAT2, dopamine is released into the cytosol (yellow-orange area). When amphetamine binds to TAAR1, it reduces dopamine receptor firing rate via potassium channels and triggers protein kinase A (PKA) and protein kinase C (PKC) signaling, resulting in DAT phosphorylation. PKA-phosphorylation causes DAT to withdraw into the presynaptic neuron (internalize) and cease transport. PKC-phosphorylated DAT may either operate in reverse or, like PKA-phosphorylated DAT, internalize and cease transport. Amphetamine is also known to increase intracellular calcium, a known effect of TAAR1 activation, which is associated with DAT phosphorylation through a CAMK-dependent pathway, in turn producing dopamine efflux.

Amphetamine and its enantiomers have been identified as potent full agonists of trace amine-associated receptor 1 (TAAR1), 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 (effluxion). 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 (effluxes) dopamine, norepinephrine, and serotonin, among other monoamines, into the cytosol in exchange.

Dextroamphetamine (the dextrorotary enantiomer) and levoamphetamine (the levorotary enantiomer) 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 (CNS) stimulation than levoamphetamine; however, levoamphetamine has slightly greater cardiovascular and peripheral effects.

Related endogenous compounds

For more details on related compounds, see Trace amines.

Amphetamine has a very similar structure and function to the endogenous trace amines, which are naturally occurring neurotransmitter molecules produced in the human body and brain. Among this group, the most closely related compounds are phenethylamine, the parent compound of amphetamine, and N-methylphenethylamine, an isomer of amphetamine (i.e., it has an identical molecular formula). In humans, phenethylamine is produced directly from L-phenylalanine by the aromatic amino acid decarboxylase (AADC) enzyme, which converts L-DOPA into dopamine as well. In turn, N‑methylphenethylamine is metabolized from phenethylamine by phenylethanolamine N-methyltransferase, the same enzyme that metabolizes norepinephrine into epinephrine. Like amphetamine, both phenethylamine and N‑methylphenethylamine regulate monoamine neurotransmission via TAAR1; unlike amphetamine, both of these substances are broken down by monoamine oxidase B, and therefore have a shorter half-life than amphetamine.

Pharmacokinetics

Amphetamine is well absorbed from the gut, and bioavailability is typically over 75% for dextroamphetamine. However, oral availability varies with gastrointestinal pH. Dextroamphetamine is a weak base with a pKa of 9–10; consequently, when the pH is basic, more of the drug is in its lipid soluble free base form, and more is absorbed through the lipid-rich cell membranes of the gut epithelium. Conversely, an acidic pH means the drug is predominantly in its water soluble cationic form, and less is absorbed.

Approximately 15–40% of dextroamphetamine circulating in the bloodstream is bound to plasma proteins.

The half-life of dextroamphetamine varies with urine pH. At normal urine pH, the half-life of dextroamphetamine is 9–11 hours. An acidic diet will reduce the half-life to 8–11 hours, while an alkaline diet will increase the range to 16–31 hours. The immediate-release and extended release variants of dextroamphetamine salts reach peak plasma concentrations at 3 hours and 7 hours post-dose respectively. Dextromphetamine is eliminated via the kidneys, with 30–40% of the drug being excreted unchanged at normal urinary pH. When the urinary pH is basic, more of the drug is in its poorly water soluble free base form, and less is excreted. When urine pH is abnormal, the urinary recovery of amphetamine may range from a low of 1% to as much as 75%, depending mostly upon whether urine is too basic or acidic, respectively. Amphetamine is usually eliminated within two days of the last oral dose. Apparent half-life and duration of effect increase with repeated use and accumulation of the drug.

CYP2D6, dopamine β-hydroxylase, flavin-containing monooxygenase, butyrate-CoA ligase, and glycine N-acyltransferase are the enzymes known to metabolize amphetamine or its metabolites in humans. Amphetamine has a variety of excreted metabolic products, including 4-hydroxyamfetamine, 4-hydroxynorephedrine, 4-hydroxyphenylacetone, benzoic acid, hippuric acid, norephedrine, and phenylacetone. Among these metabolites, the active sympathomimetics are 4‑hydroxyamphetamine, 4‑hydroxynorephedrine, and norephedrine.

The main metabolic pathways involve aromatic para-hydroxylation, aliphatic alpha- and beta-hydroxylation, N-oxidation, N-dealkylation, and deamination. The known pathways include:

Metabolic pathways of amphetamine

4-Hydroxyphenylacetone

Phenylacetone

Benzoic acid

Hippuric acid

Amphetamine

Norephedrine

4-Hydroxyamphetamine

4-Hydroxynorephedrine

Para-
Hydroxylation

Para-
Hydroxylation

Para-
Hydroxylation

Beta-
Hydroxylation

Beta-
Hydroxylation

Oxidative
Deamination

Oxidation

Glycine
Conjugation

The primary active metabolites of amphetamine are 4-hydroxyamphetamine and norephedrine; however, most of an administered dose is excreted as amphetamine itself and the inactive metabolites. Benzoic acid is metabolized by butyrate-CoA ligase into an intermediate product, benzoyl-CoA, which is then metabolized by glycine N-acyltransferase into hippuric acid.

History, society, and culture

Main article: History and culture of amphetamines

Racemic amphetamine was first synthesized under the chemical name "phenylisopropylamine" in Berlin, 1887 by the Romanian chemist Lazar Edeleanu. It was not widely marketed until 1932, when the pharmaceutical company Smith, Kline & French (now known as GlaxoSmithKline) 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.

Three years later, in 1935, the medical community became aware of the stimulant properties of amphetamine, specifically dexamfetamine, and in 1937 Smith, Kline, and French introduced tablets under the tradename Dexedrine. In the United States, Dexedrine was approved to treat narcolepsy, attention disorders, depression, and obesity. In Canada, epilepsy and parkinsonism were also approved indications. Dexamfetamine 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 dexamfetamine and amobarbital (a barbiturate) sold under the tradename Dexamyl and, in the 1950s, an extended release capsule (the "Spansule"). Preparations containing dextroamphetamine were also used in World War II as a treatment against fatigue.

It quickly became apparent that dexamfetamine 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. Dexamfetamine, 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 (Italy), Curban (US), Obetrol (Switzerland), Simpamina (Italy), Dexedrine/GSK (US & Canada), Dexedrine/UCB (United Kingdom), Dextropa (Portugal), and Stild (Spain).

In October 2010, GlaxoSmithKline sold the rights for Dexedrine Spansule to Amedra Pharmaceuticals (a subsidiary of CorePharma).

The U.S. Air Force uses dexamfetamine 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

Pharmaceuticals Brand name United States Adopted Name (D:L) ratio of salts Dosage form Source Adderall – 3:1 tablet Adderall XR – 3:1 capsule Dexedrine dextroamphetamine sulfate 1:0 capsule ProCentra dextroamphetamine sulfate 1:0 liquid Vyvanse lisdexamfetamine dimesylate 1:0 capsule Zenzedi dextroamphetamine sulfate 1:0 tablet

The skeletal structure of lisdexamfetamine

Dextroamphetamine sulfate

Dexamphetamine 5 mg generic name tablets

In the United States, an instant-release (IR) tablet preparation of dextroamphetamine sulfate is available under the brand name Dextrostat, in 5 mg and 10 mg strengths, with generic versions marketed by Barr (Teva Pharmaceutical Industries), Mallinckrodt Pharmaceuticals and Wilshire Pharmaceuticals. Dextroamphetamine sulfate is also available as a controlled-release (CR) capsule preparation in strengths of 5 mg, 10 mg, and 15 mg under the brand name Dexedrine Spansule, with generic versions marketed by Barr and Mallinckrodt. A bubblegum flavored oral solution is available under the brand name ProCentra, manufactured by FSC Pediatrics, which is designed to be an easier method of administration in children who have difficulty swallowing tablets, each 5 mL contains 5 mg dexamfetamine.

In Australia, dexamphetamine is available in bottles of 100 instant release 5 mg tablets as a generic drug. or slow release dexamfetamine preparations may be compounded by individual chemists. Similarly, in the United Kingdom it is only available in 5 mg instant release sulfate tablets under the generic name dexamfetamine sulphate having had been available under the brand name Dexedrine prior to UCB Pharma disinvesting the product to another pharmaceutical company (Auden Mckenzie).

Lisdexamfetamine

Main article: Lisdexamfetamine

Dextroamphetamine is the active metabolite of the prodrug lisdexamfetamine (L-lysine-dextroamphetamine), available by the brand name Vyvanse (lisdexamfetamine dimesylate). Lisdexamfetamine is metabolised in the gastrointestinal tract, while dextroamphetamine's metabolism is hepatic. Lisdexamfetamine is therefore an inactive compound until it is converted into an active compound by the digestive system. Vyvanse is marketed as once-a-day dosing as it provides a slow release of dextroamphetamine into the body. Vyvanse is available as capsules, and in six strengths; 20 mg, 30 mg, 40 mg, 50 mg, 60 mg, and 70 mg. The conversion rate of lisdexamfetamine dimesylate to dextroamphetamine base is 0.2948, thus a 30 mg-strength Vyvanse capsule is molecularly equivalent to 8.844 mg dexamfetamine base.

Amphetamine salts (Adderall)

Adderall 20 mg tablets, some broken in half, with a lengthwise-folded US dollar bill along the bottom

Main article: Adderall

Another pharmaceutical that contains dextroamphetamine is commonly known by the brand name Adderall. The drug formulation of Adderall, including both the immediate release (IR) and extended release (XR) forms, is:

One-quarter racemic (d,l-)amphetamine aspartate monohydrate

One-quarter dextroamphetamine saccharate

One-quarter dextroamphetamine sulfate

One-quarter racemic (d,l-)amphetamine sulfate

Adderall is roughly three-quarters dextroamphetamine, with it accounting for 72.7% of the amphetamine base in Adderall (the remaining percentage is levoamphetamine). The salt ratio, as noted above, is 75%:25% or 3:1 dextroamphetamine to levoamphetamine.

References

Notes

Reference notes

External links

• Dexedrine Spansule - Official U.S. Website
• Dextroamphetamine consumer information from Drugs.com
• Poison Information Monograph (PIM 178: Dexamphetamine Sulphate)

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English Journal

• Amphetamine increases errors during episodic memory retrieval.

• Ballard ME1, Gallo DA, de Wit H.Author information 1From the Departments of *Psychiatry and Behavioral Neuroscience, and †Psychology, University of Chicago, Chicago, IL.AbstractModerate doses of stimulant drugs are known to enhance memory encoding and consolidation, but their effects on memory retrieval have not been explored in depth. In laboratory animals, stimulants seem to improve retrieval of emotional memories, but comparable studies have not been carried out in humans. In the present study, we examined the effects of dextroamphetamine (AMP) on retrieval of emotional and unemotional stimuli in healthy young adults, using doses that enhanced memory formation when administered before encoding in our previous study. During 3 sessions, healthy volunteers (n = 31) received 2 doses of AMP (10 and 20 mg) and placebo in counterbalanced order under double-blind conditions. During each session, they first viewed emotional and unemotional pictures and words in a drug-free state, and then 2 days later their memory was tested, 1 hour after AMP or placebo administration. Dextroamphetamine did not affect the number of emotional or unemotional stimuli remembered, but both doses increased recall intrusions and false recognition. Dextroamphetamine (20 mg) also increased the number of positively rated picture descriptions and words generated during free recall. These data provide the first evidence that therapeutic range doses of stimulant drugs can increase memory retrieval errors. The ability of AMP to positively bias recollection of prior events could contribute to its potential for abuse.
• Journal of clinical psychopharmacology.J Clin Psychopharmacol.2014 Feb;34(1):85-92. doi: 10.1097/JCP.0000000000000039.
• Moderate doses of stimulant drugs are known to enhance memory encoding and consolidation, but their effects on memory retrieval have not been explored in depth. In laboratory animals, stimulants seem to improve retrieval of emotional memories, but comparable studies have not been carried out in huma
• PMID 24135845

• Amphetamine fails to alter cued recollection of emotional images: study of encoding, retrieval, and state-dependency.

• Weafer J1, Gallo DA2, de Wit H1.Author information 1Department of Psychiatry and Behavioral Neuroscience, University of Chicago, Chicago, Illinois, United States of America.2Department of Psychology, University of Chicago, Chicago, Illinois, United States of America.AbstractStimulant drugs facilitate both encoding and retrieval of salient information in laboratory animals, but less is known about their effects on memory for emotionally salient visual images in humans. The current study investigated dextroamphetamine (AMP) effects on memory for emotional pictures in healthy humans, by administering the drug only at encoding, only at retrieval, or at both encoding and retrieval. During the encoding session, all participants viewed standardized positive, neutral, and negative pictures from the International Affective Picture System (IAPS). 48 hours later they attended a retrieval session testing their cued recollection of these stimuli. Participants were randomly assigned to one of four conditions (N = 20 each): condition AP (20 mg AMP at encoding and placebo (PL) at retrieval); condition PA (PL at encoding and AMP at retrieval); condition AA (AMP at encoding and retrieval); or condition PP (PL at encoding and retrieval). Amphetamine produced its expected effects on physiological and subjective measures, and negative pictures were recollected more frequently than neutral pictures. However, contrary to hypotheses, AMP did not affect recollection for positive, negative, or neutral stimuli, whether it was administered at encoding, retrieval, or at both encoding and retrieval. Moreover, recollection accuracy was not state-dependent. Considered in light of other recent drug studies in humans, this study highlights the sensitivity of drug effects to memory testing conditions and suggests future strategies for translating preclinical findings to human behavioral laboratories.
• PloS one.PLoS One.2014 Feb 27;9(2):e90423. doi: 10.1371/journal.pone.0090423. eCollection 2014.
• Stimulant drugs facilitate both encoding and retrieval of salient information in laboratory animals, but less is known about their effects on memory for emotionally salient visual images in humans. The current study investigated dextroamphetamine (AMP) effects on memory for emotional pictures in hea
• PMID 24587355

• Pharmacological treatment and demographic characteristics of pediatric patients with Attention Deficit Hyperactivity Disorder, Sweden.

• Bahmanyar S1, Sundström A, Kaijser M, von Knorring AL, Kieler H.Author information 1Centre for Pharmacoepidemiology and Clinical Epidemiology Unit, Department of Medicine, Karolinska Institutet, SE-171 76 Stockholm, Sweden; Faculty of Medicine, Golestan University of Medical Sciences, Gorgan, Iran. Electronic address: Shahram.Bahmanyar@ki.se.AbstractThe aim of this study was to describe the pediatric population with ADHD and their pharmacological treatment. Using the Swedish National Patient Register and the Prescribed Drug Register we identified individuals below 19 years of age who were diagnosed or medically treated for ADHD for the first time 2006-2007. The unique patient identifiers were used to link information from the two registers to describe demographic characteristics, hospital care and drug treatments. Logistic regression model estimated the association between age, sex, frequency of hospitalization, diagnosis or treatment for other mental disorders and risk of gap in the treatment. Totally the study included 7931 patients of whom 74% were males. The mean age at first diagnosis was 12 years. Some 84% were medically treated for ADHD and approximately 90% received methylphenidate as the first substance. Combination therapy was rare and the most common combination was methylphenidate and atomoxetine. More than 55% of the patients, which could be followed up for two years after start of treatment, had at least one treatment gap of six months. Older age at diagnosis, lower number of hospitalizations and comorbidity with other mental disorders increased risks of gaps in medication. Approximately one fifth of the patients recorded in the National Patient Register as diagnosed with ADHD did not receive pharmacological treatment. Medication adherence seems to be low, when measured as gaps in treatment.
• European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology.Eur Neuropsychopharmacol.2013 Dec;23(12):1732-8. doi: 10.1016/j.euroneuro.2013.07.009. Epub 2013 Aug 1.
• The aim of this study was to describe the pediatric population with ADHD and their pharmacological treatment. Using the Swedish National Patient Register and the Prescribed Drug Register we identified individuals below 19 years of age who were diagnosed or medically treated for ADHD for the first ti
• PMID 23953271

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Related Pictures

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★リンクテーブル★

リンク元	「デキストロアンフェタミン」

「デキストロアンフェタミン」

　　[★]

英

dextroamphetamine

商

Adderall, Dexedrine, Dextrostat

関

d-アンフェタミン d-amphetamine、デキサンフェタミン。薬物濫用