Racemic amphetamine skeleton
|Chemical class||Substituted derivatives of amphetamine|
Substituted amphetamines are a class of compounds based upon the amphetamine structure; it includes all derivative compounds which are formed by replacing, or substituting, one or more hydrogen atoms in the amphetamine core structure with substituents. The compounds in this class span a variety of pharmacological subclasses, including stimulants, empathogens, and hallucinogens, among others. Examples of substituted amphetamines are amphetamine (itself), methamphetamine, ephedrine, cathinone, phentermine, mephentermine, bupropion, methoxyphenamine, selegiline, amfepramone, pyrovalerone, MDMA (ecstasy), and DOM (STP).
Some of amphetamine's substituted derivatives occur in nature, for example in the leaves of Ephedra and khat plants. These have been used since antiquity (at least 1000 years ago) for their pharmacological effects. Amphetamine was first produced at the end of the 19th century. By the 1930s, amphetamine and some of its derivative compounds found use as decongestants in the symptomatic treatment of colds and also occasionally as psychoactive agents. Their effects on the central nervous system are diverse, but can be summarized by three overlapping types of activity: psychoanaleptic, hallucinogenic and empathogenic. Various substituted amphetamines may cause these actions either separately or in combination.
|Generic or Trivial Name||Chemical Name||# of Subs|
|Phenylpropanolamine (PPA)||β-Hydroxyamphetamine, (1R,2S)-||1|
|para-Bromoamphetamine (PBA, 4-BA)||4-Bromoamphetamine||1|
|para-Chloroamphetamine (PCA, 4-CA)||4-Chloroamphetamine||1|
|para-Fluoroamphetamine (PFA, 4-FA, 4-FMP)||4-Fluoroamphetamine||1|
|para-Iodoamphetamine (PIA, 4-IA)||4-Iodoamphetamine||1|
|Pseudoephedrine (PSE)||β-Hydroxy-N-methylamphetamine, (1S,2S)-||2|
|para-Fluoromethamphetamine (PFMA, 4-FMA)||4-Fluoro-N-methylamphetamine||2|
|Nordefrin (α-Me-NE)||β,3,4-Trihydroxyamphetamine, (R)-||3|
A variety of prodrugs of amphetamine and/or methamphetamine exist, and include amfecloral, amphetaminil, benzphetamine, clobenzorex, D-deprenyl, dimethylamphetamine, ethylamphetamine, fencamine, fenethylline, fenproporex, furfenorex, lisdexamfetamine, mefenorex, mesocarb, prenylamine, and selegiline.
Amphetamines are a subgroup of the substituted phenethylamine class of compounds. Substitution of hydrogen atoms results in a large class of compounds. Typical reaction is substitution by methyl and sometimes ethyl groups at the amine and phenyl sites:
Ephedra was used 5000 years ago in China as a medicinal plant; its active ingredients are alkaloids ephedrine, pseudoephedrine, norephedrine (phenylpropanolamine) and norpseudoephedrine (cathine). Natives of Yemen and Ethiopia have a long tradition of chewing khat leaves to achieve a stimulating effect. The active substances of khat are cathinone and, to a lesser extent, cathine.
Amphetamine was first synthesized in 1887 by Romanian chemist Lazăr Edeleanu, although its pharmacological effects remained unknown until the 1930s. MDMA was produced in 1912 (according to other sources in 1914) as an intermediate product. However, this synthesis also went largely unnoticed. In the 1920s, both methamphetamine and the dextrorotatory optical isomer of amphetamine, dextroamphetamine, were synthesized. This synthesis was a by-product of a search for ephedrine, a bronchodilator used to treat asthma extracted exclusively from natural sources. Over-the-counter use of substituted amphetamines was initiated in the early 1930s by the pharmaceutical company Smith, Kline & French (now part of GlaxoSmithKline), as a medicine (Benzedrine) for colds and nasal congestion. Subsequently, amphetamine was used in the treatment of narcolepsy, obesity, hay fever, orthostatic hypotension, epilepsy, Parkinson's disease, alcoholism and migraine. The "reinforcing" effects of substituted amphetamines were quickly discovered, and the misuse of substituted amphetamines had been noted as far back as 1936.
During World War II, amphetamines were used by the German military to keep their tank crews awake for long periods, and treat depression. It was noticed that extended rest was required after such artificially induced activity. The widespread use of substituted amphetamines began in postwar Japan and quickly spread to other countries. Modified "designer amphetamines" gained popularity since the 1960s, such as MDA and PMA. In 1970, the United States adopted "the Controlled Substances Act" that limited non-medical use of substituted amphetamines. Street use of PMA was noted in 1972. MDMA emerged as a substitute to MDA in the early 1970s. American chemist Alexander Shulgin first synthesized the drug in 1976 and through him the drug was briefly introduced into psychotherapy. Recreational use grew and in 1985 MDMA was banned by the US authorities in an emergency scheduling initiated by the Drug Enforcement Administration.
Since the mid-1990s, MDMA has become a popular entactogenic drug among the youth and quite often non-MDMA substances were sold as ecstasy. Ongoing trials are investigating its efficacy as an adjunct to psychotherapy in the management of treatment-resistant post-traumatic stress disorder (PTSD).
|Agents||Legal status by 2009.|
|UN Convention on Psychotropic Substances of 1971||US||Russia||Australia|
|Amphetamine (racemic)||Schedule II||Schedule II||Schedule II||Schedule 8|
|Dextroamphetamine (D-amphetamine)||Schedule II||Schedule II||Schedule I||Schedule 8|
|Levoamphetamine (L-amphetamine)||Schedule II||Schedule II||Schedule III||Schedule 8|
|Methamphetamine||Schedule II||Schedule II||Schedule I||Schedule 8|
|Cathinone Methcathinone||Schedule I||Schedule I||Schedule I||Schedule 9|
|MDA, MDMA, MDEA||Schedule I||Schedule I||Schedule I||Schedule 9|
|PMA||Schedule I||Schedule I||Schedule I||Schedule 9|
|DOB, DOM, 3,4,5-TMA||Schedule I||Schedule I||Schedule I||Schedule 9|
Substituted amphetamines, which are also called phenylpropylamino alkaloids, are a diverse group of nitrogen-containing compounds that feature a phenethylamine backbone with a methyl group at the α-position relative to the nitrogen (Figure 1). Countless variation in functional group substitutions has yielded a collection of synthetic drugs with diverse pharmacological properties as stimulants, empathogens and hallucinogens . ... Beyond (1R,2S)-ephedrine and (1S,2S)-pseudoephedrine, myriad other substituted amphetamines have important pharmaceutical applications. The stereochemistry at the α-carbon is often a key determinant of pharmacological activity, with (S)-enantiomers being more potent. For example, (S)-amphetamine, commonly known as d-amphetamine or dextroamphetamine, displays five times greater psychostimulant activity compared with its (R)-isomer . Most such molecules are produced exclusively through chemical syntheses and many are prescribed widely in modern medicine. For example, (S)-amphetamine (Figure 4b), a key ingredient in Adderall® and Dexedrine®, is used to treat attention deficit hyperactivity disorder (ADHD) . ...
[Figure 4](b) Examples of synthetic, pharmaceutically important substituted amphetamines.
The simplest unsubstituted phenylisopropylamine, 1-phenyl-2-aminopropane, or amphetamine, serves as a common structural template for hallucinogens and psychostimulants. Amphetamine produces central stimulant, anorectic, and sympathomimetic actions, and it is the prototype member of this class (39).