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Stimulants (also referred to as psychostimulants) are psychoactive drugs which induce temporary improvements in either mental or physical functions or both. Examples of these kinds of effects may include enhanced alertness, wakefulness, and locomotion, among others. Due to their effects typically having an "up" quality to them, stimulants are also occasionally referred to as "uppers". Depressants or "downers", which decrease mental and/or physical function, are in stark contrast to stimulants and are considered to be their functional opposites. Stimulants are widely used throughout the world as prescription medicines and as illicit substances of recreational use or abuse.
Stimulants produce a variety of different kinds of effects by enhancing the activity of the central and peripheral nervous systems. Common effects, which vary depending on the substance in question, may include enhanced alertness, awareness, wakefulness, endurance, productivity, and motivation, increased arousal, locomotion, heart rate, and blood pressure, and the perception of a diminished requirement for food and sleep. Many stimulants are also capable of improving mood and relieving anxiety, and some can even induce feelings of euphoria. However, many of these drugs are also capable of causing anxiety and heart failure, even the ones that may paradoxically reduce it to a degree at the same time. Stimulants exert their effects through a number of different pharmacological mechanisms, the most prominent of which include facilitation of norepinephrine (noradrenaline) and/or dopamine activity (e.g., via monoamine transporter inhibition or reversal), adenosine receptor antagonism, and nicotinic acetylcholine receptor agonism.
Stimulants are used both individually and clinically for therapeutic purposes in the treatment of a number of indications, including the following:
Recently, there have been improvements in the area of stimulant pharmacology, producing a class of chemicals known as ampakines, or eugeroics, (good arousal). These stimulants tend to increase alertness without the peripheral (body) effects or addiction/tolerance/abuse potential of the traditional stimulants. They have minimal effect on sleep structure, and do not cause rebound hypersomnolence or "come down" effects. Ampakines such as ampalex and CX717 have been developed but are still in clinical trials and have not yet been sold commercially. Another compound with similar effects to these drugs is carphedon, which is sold as a general stimulant in Russia under the brand name Phenotropil.
Amphetamines are a group of phenylethylamine stimulants such as amphetamine and methamphetamine. Like NDRIs, amphetamine increases the levels of norepinephrine and dopamine in the brain via reuptake inhibition; however, the more important mechanism by which amphetamines cause stimulation is through the direct release of these catecholamines from storage vesicles in cells. Amphetamines are known to cause elevated mood and euphoria as well as rebound depression and anxiety.
Amphetamines are often used for their therapeutic effects; physicians occasionally prescribe amphetamines to treat major depression, where subjects do not respond well to traditional SSRI medications, and numerous studies have demonstrated the effectiveness of drugs such as Adderall in controlling symptoms associated with ADD/ADHD. Due to their availability and fast-acting effects, amphetamines are prime candidates for abuse.
Khat contains a monoamine alkaloid called cathinone, an amphetamine-like stimulant, which is said to cause excitement, loss of appetite and euphoria. In 1980, the World Health Organization (WHO) classified it as a drug of abuse that can produce mild to moderate psychological dependence (less than tobacco or alcohol), although the WHO does not consider khat to be seriously addictive. It is a controlled substance in some countries, such as the United States, Canada and Germany, while its production, sale and consumption are legal in other nations, including Djibouti, Ethiopia, Somalia and Yemen.
Bupropion (// bew-PROH-pee-on) is a drug marketed as Wellbutrin, Budeprion, Prexaton, Elontril, Aplenzin, or other trade names. It is one of the most frequently prescribed antidepressants in the United States. Marketed in lower-dose formulations as Zyban, Voxra, or other names, it is also widely used as a smoking cessation aid. It is taken in the form of pills, and in the United States is available only by prescription.
Medically, bupropion serves as a non-tricyclic antidepressant fundamentally different from most commonly prescribed antidepressants such as selective serotonin reuptake inhibitors (SSRIs). It is an effective antidepressant on its own, but is also popular as an add-on medication in cases of incomplete response to first-line SSRI antidepressants. In contrast to many other antidepressants, it does not cause weight gain or sexual dysfunction. The most important side effect is an increase in risk for epileptic seizures, which lead to the recommended dosage to be reduced. 300mg a day (for average body weight) has been shown to maintain the same 0.1% unprovoked seizure rate of the general population.
Bupropion affects a number of neurotransmitter systems, and its mechanisms of action are only partly understood. The primary pharmacological action of the drug is as a mild dopamine reuptake inhibitor and also a much weaker norepinephrine reuptake inhibitor as well as a nicotinic acetylcholine receptor antagonist. Chemically, bupropion belongs to the class of aminoketones and is similar in structure to stimulants such as cathinone and amfepramone, and to phenethylamines in general.
Bupropion is patented by GlaxoSmithKline. It was originally called amfebutamone, before being renamed in 2000. Its chemical name is 3-chloro-N-tert-butyl-β-ketoamphetamine. It is a substituted cathinone (β-ketoamphetamine), as well as a substituted amphetamine.
Ephedrine is a sympathomimetic amine similar in molecular structure to the well-known drugs phenylpropanolamine and methamphetamine, as well as to the important neurotransmitter epinephrine (adrenalin). Ephedrine is commonly used as a stimulant, appetite suppressant, concentration aid, decongestant, and to treat hypotension associated with anaesthesia.
Chemically, it is an alkaloid with a phenethylamine skeleton found in various plants in the genus Ephedra (family Ephedraceae). It works mainly by increasing the activity of norepinephrine (noradrenalin) on adrenergic receptors. It is most usually marketed as the hydrochloride or sulfate salt.
The herb má huáng (麻黄, Ephedra sinica), used in traditional Chinese medicine (TCM), contains ephedrine and pseudoephedrine as its principal active constituents. The same may be true of other herbal products containing extracts from other Ephedra species.
Levoamphetamine (also levamfetamine, (R)-amphetamine or (−)-amphethamine) is a psychostimulant known to increase wakefulness and focus in association with decreased appetite and fatigue. Levoamphetamine is the levorotatory stereoisomer of the amphetamine molecule. It possesses much weaker dopaminergic activity than the dextrorotary isomer (dextroamphetamine) and acts as a selective releasing agent of norepinephrine, similarly to levomethamphetamine. The amphetamine racemate contains two stereoisomers, dextroamphetamine and levoamphetamine, both exhibiting amphetaminergic (amphetamine-like) effects.
MDA differs from most stimulants in that its primary pharmacological effect is on the neurotransmitter serotonin rather than dopamine, epinephrine, or norepinephrine. Because of this, it is considered to be primarily an entactogen or an empathogen.
Methylenedioxymethamphetamine (MDMA), known by its common street name "Ecstasy", typically comes in either tablet, capsule, or powder/crystal form. It had a medical application as a treatment for depression and a psychotherapy aid until 1985 when the DEA listed MDMA as a Schedule I controlled substance, prohibiting most medical studies and applications. Notably, MDMA is also unique and very popular for its entactogenic properties. The stimulant effects of MDMA include hypertension, anorexia (appetite loss), euphoria, social disinhibition, insomnia (or enhanced wakefulness), improved energy, increased arousal, and increased perspiration, among others.
MDMA differs from most stimulants in that its primary pharmacological effect is on the neurotransmitter serotonin rather than dopamine, epinephrine, or norepinephrine. Because of this, it is considered to be primarily an entactogen or an empathogen.
Dextromethamphetamine and levomethamphetamine (see earlier sections) are the two enantiomers of methamphetamine, and are separate medications indicated for different uses. Unless otherwise specified "methamphetamine" refers to a racemic mixture (50%/50%) of the two.
Unlike amphetamines, and other substances which are dopamine agonists, which either stimulate the release or inhibit the reuptake of dopamine or norepinephrine (which itself is synthesized from dopamine, typically with the help of the amino acid SAM-e, also available as a supplement), dopamine precursors are used by the body in the manufacturing of dopamine.
L-Dopa can cross the blood-brain barrier, and can be converted by the body into dopamine.
L-Tyrosine is the precursor that is 'closest' to being dopamine among those supplements legally available without prescription in most jurisdictions. It cannot cross the blood-brain barrier, but is converted by the body into L-Dopa, which can. Tyrosine must be taken on an empty stomach and the dosages recommended by most supplement companies may not be sufficient for a noticeable effect.
Phenylalanine is 'one step back' from L-Tyrosine--it must be converted into Tyrosine before the Tyrosine can be converted into L-Dopa, which in turn becomes dopamine.
Adrafinil is the prodrug of Modafinil, and is metabolized into it in about one hour, when taken on an empty stomach.
Armodafinil is an enantiopure (non-racemic) version of Modafinil with similar psychoactive properties.
JZ-IV-10 is also an SNDRI.
Modafinil (Provigil/Alertec/Modavigil) is an analeptic drug approved by the (FDA) for the treatment of narcolepsy, shift work sleep disorder, and excessive daytime sleepiness associated with obstructive sleep apnea.
Modafinil, like other stimulants, increases the release of monoamines but also elevates hypothalamic histamine levels, leading some researchers to consider Modafinil a "wakefulness promoting agent" rather than a classic amphetamine-like stimulant.
Modafinil has been shown to be effective in the treatment of Attention-Deficit Hyperactivity Disorder (ADHD), depression, cocaine addiction, Parkinson's Disease, schizophrenia, shift workers' sleep disorder and disease-related fatigue.
Nicotine is the active chemical constituent in tobacco, which is available in many forms, including cigarettes, cigars, chewing tobacco, and smoking cessation aids such as nicotine patches, nicotine gum and electronic cigarettes. Nicotine is used widely throughout the world for its stimulating, and relaxing effects.
These drugs inhibit the reuptake of norepinephrine and/or dopamine, resulting in increased extracellular levels and therefore enhanced neurotransmission, ultimately producing a stimulant effect. Many of these compounds are used as ADHD medications and antidepressants. The two best-known NRIs are atomoxetine (Strattera) and reboxetine (Edronax). Many of these drugs have a considerably lower abuse potential in comparison to other stimulants like the amphetamines and cocaine. Reboxetine has been withdrawn from the market in the USA due to unproven efficacy and an unacceptable occurrence of dangerous side effects.
Cocaine is an SNDRI. Cocaine is made from the leaves of the coca shrub, which grows in the mountain regions of South American countries such as Bolivia, Colombia, and Peru. In Europe, North America, and in some parts of Asia, the most common form of cocaine is a white crystalline powder. Cocaine is a stimulant but is not normally prescribed therapeutically for its stimulant properties, although it sees clinical use as a local anesthetic, particularly in ophthalmology. Most cocaine use is recreational and its abuse potential is high, and so its sale and possession are strictly controlled in most jurisdictions. Other tropane derivative drugs related to cocaine are also known such as troparil and lometopane but have not been widely sold or used recreationally.
Fenetylline is a prodrug of both Theophyline and Amphetamine.
Methylphenidate (MPH; Ritalin, Concerta, Metadate, or Methylin) is a drug approved for treatment of attention-deficit hyperactivity disorder, postural orthostatic tachycardia syndrome, and narcolepsy. It belongs to the piperidine class of compounds and increases the levels of dopamine and norepinephrine in the brain through reuptake inhibition of the monoamine transporters. It also increases the release of dopamine and norepinephrine. MPH possesses structural similarities to amphetamine, and, though it is less potent, its pharmacological effects are even more closely related to those of cocaine.
Caffeine is a stimulant compound that is found naturally in coffee, tea, and to a lesser degree, in cocoa or chocolate. It is included in many soft drinks, as well as a larger amount in energy drinks. Caffeine is the world's most widely used psychoactive drug and by far the most common stimulant. The vast majority (over 85%) of people in the United States consume caffeine on a daily basis.A few jurisdictions restrict its sale and use. Caffeine is also included in some medications, usually for the purpose of enhancing the effect of the primary ingredient, or reducing one of its side effects (especially drowsiness). Tablets containing standardized doses of caffeine are also widely available.
Yohimbine is a psychoactive drug of the tryptamine chemical class with stimulant and aphrodisiac effects. Yohimbine is sometimes used to remedy Type-2 Diabetes in animals and humans that carry the polymorphisms of the α2A-adrenergic receptor gene.
Abuse of central nervous system stimulants is common. Addiction to some CNS stimulants can quickly lead to medical, psychiatric and psychosocial deterioration. Drug tolerance, dependence, sensitization as well as a withdrawal syndrome can occur.
The presence of stimulants in the body may be tested by a variety of procedures. Serum and urine are the common sources of testing material although saliva is sometimes used. Commonly used tests include chromatography, immunologic assay and mass spectrometry. Patients taking ADHD-prescribed, Adderall-type amphetamine compounds are commonly surprised upon being tested as "positive" for "meth", or methamphetamine (Desoxyn its licit, FDA-licensed, medicinal form) in forensically unsophisticated urinalysis, as methamphetamine is the active ingredient of the drug Desoxyn, and is chemically similar to the active ingredients of other ADHD medications.
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