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Amphetamines

Amphetamines

Definition

Amphetamines are a group of drugs that stimulate the central nervous system. Some of the brand names of amphetamines sold in the United States are Dexedrine, Biphetamine, Das, Dexampex, Ferndex, Oxydess II, Spancap No 1, Desoxyn, and Methampex. Some generic names of amphetamines include amphetamine, dextroamphetamine, and methamphetamine.

Purpose

Amphetamines stimulate the nervous system and are used in the treatment of depression, attention-deficit disorder, obesity , and narcolepsy , a disorder that causes individuals to fall asleep at inappropriate times during the day. Amphetamines produce considerable side effects and are especially toxic in large quantities. Amphetamines are commonly abused recreational drugs and are highly addictive.

Description

Amphetamines are usually given orally and their effects can last for hours. Amphetamines produce their effects by altering chemicals that transmit nerve messages in the body.

Recommended dosage

The typical dose for amphetamines in the treatment of narcolepsy in adults ranges from 5 mg to 60 mg per day. These daily doses are usually divided into at least two small doses taken during the day. Doses usually start on the low end of the range and are increased until the desired effects occur. Children over the age of 12 years with narcolepsy receive 10 mg per day initially. Children between the ages of six and 12 years start with 5 mg per day. The typical dose for adults with obesity ranges from 5 mg to 30 mg per day given in divided doses. The medication is usually given about one-half hour to one hour before meals.

The typical starting dose of amphetamines given to children with attention-deficit disorder over the age of six years is 5 mg per day. This is increased by 5 mg per day over a period of time until the desired effect is achieved. Children under the age of six years with this condition are usually started at 2.5 mg per day.

Precautions

People who are taking amphetamines should not stop taking these drugs suddenly. The dose should be lowered gradually and then discontinued. Amphetamines should only be used while under the supervision of a physician. People should generally take the drug early in the day so that it does not interfere with sleep at night. Hazardous activities should be avoided until the person's condition has been stabilized with medication. The effects of amphetamine can last up to 20 hours after the medication has last been taken. Amphetamine therapy given to women for medical reasons does not present a significant risk to the developing fetus for congenital disorders. In such cases, there may be mild withdrawal in the newborn. However, illicit use of amphetamines for non-medical reasons presents a significant risk to the fetus and the newborn because of uncontrolled doses.

Amphetamines are highly addictive and should be used only if alternative approaches have failed. They should be used with great caution in children under three years of age, anyone with a history of slightly elevated blood pressure, people with neurological tics, and in individuals with Tourette's syndrome. Amphetamines should not be taken by individuals with a history of an overactive thyroid, those with moderate-to-severe high blood pressure, those with the eye disease called glaucoma, those who have severe arteriosclerosis (hardening of the arteries), or anyone with psychotic symptoms (hallucinations and delusions ). Individuals with a history of drug abuse, psychological agitation, or cardiovascular system disease should also not receive amphetamine therapy. In addition, patients who have taken MAO inhibitors, a type of antidepressant, within the last 14 days should not receive amphetamines. MAO inhibitors include phenelzine (Nardil), and tranylcypromine (Parnate).

Side effects

The most common side effects that are associated with amphetamines include the development of an irregular heartbeat, increased heart rate, increased blood pressure, dizziness, insomnia , restlessness, headache, shakiness, dry mouth, metallic taste, diarrhea, constipation, and weight loss. Other side effects can include changes in sexual drive, nausea, vomiting, allergic reactions, chills, depression, irritability, and other problems involving the digestive system. High doses, whether for medical purposes or illicit ones, can cause addiction , dependence, increased aggression, and, in some cases, psychotic episodes.

Interactions

Patients taking amphetamines should always tell their physicians and dentists that they are using this medication. Patients should consult their physician before taking any over-the-counter medication while taking amphetamines. The interaction between over-the-counter cold medications with amphetamine, for instance, is particularly dangerous because this combination can significantly increase blood pressure. Such cold medications should be avoided when using amphetamine unless a physician has carefully analyzed the combination.

The combination of amphetamines and antacids slows down the ability of the body to eliminate the amphetamine. Furazolidone (Furoxone) combined with amphetamine can significantly increase blood pressure. Sodium bicarbonate can reduce the amount of amphetamine eliminated from the body and dangerously increase amphetamine levels in the body. Certain medications taken to control high blood pressure, including guanadrel (Hylorel) and guanethidine (Ismelin), MAO inhibitors, and selegiline (Eldepryl) should not be used in conjunction with amphetamines. In addition, tricyclic antidepressants [including desipramine (Norpramin) and imipramine (Tofranil)], antihistamines, and anticonvulsant drugs should not be combined with amphetamines.

Resources

BOOKS

Consumer Reports staff. Consumer Reports Complete Drug Reference. 2002 ed. Denver: Micromedex Thomson Healthcare, 2001.

Ellsworth, Allan J. and others. Mosby's Medical Drug Reference, 20012002. St. Louis: Mosby, 2001.

Hardman, Joel G. and Lee E. Limbird, eds. Goodman & Gilman's The Pharmacological Basis of Therapeutics. 10th ed. New York: McGraw-Hill, 2001.

Mosby's GenRx Staff. Mosby's GenRx. 9th ed. St. Louis: Mosby, 1999.

Venes, Donald and Clayton L. Thomas. Taber's Cyclopedic Medical Dictionary. 19th ed. Philadelphia: F. A. Davis, 2001.

Mark Mitchell, M.D.

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Amphetamines

Amphetamines

Amphetamines are a family of chemical compounds that are indirect stimulants of the central nervous system (CNS). Amphetamines cause the increased release into the brain of dopamine and norepinephrine, two endogenous (produced by the body) chemical messengers, which in turn stimulate the nervous system. Many drug abusers seeking a boost of physical energy and mental stimulation consume amphetamines due to their cocaine-like behavioral effects. Determining the presence or absence of amphetamines in the blood is included in most forensic drug screening tests.

Effects of amphetamines that may be experienced include: increased alertness, appetite inhibition, insomnia, decreased fatigue, and emotional euphoria. In high doses, amphetamines can induce delirium, panic attacks, confusion, aggressiveness, and suicidal tendencies. Chronic users sometimes develop a state of amphetamine-induced psychosis that shares similarities with an acute schizophrenic crisis. Drug abusers usually inject amphetamines intravenously or inhale them by smoking.

MDMA (Methylenedioxymethamphetamine), an amphetamine derivative also known as Ecstasy, is swallowed in tablets or capsules, in doses ranging from 60120 milligrams, usually in association with alcoholic drinks. Drug abusers in general tend to consume these stimulants together with alcohol or marijuana, whose alkaloids further enhance the effects of amphetamines. The amphetamine-induced euphoric state lasts an average of 46 hours, which is more than twice the time of cocaine effects.

Like cocaine, some amphetamines also cause addiction and progressive tolerance within a few weeks of use, leading its users to increase doses to achieve the same initial effects. Other physical effects of amphetamine abuse are cardiac arrhythmias, dangerously high blood pressure, chest pain, circulatory collapse, chills, excessive perspiration, and headaches. Nausea, anorexia, diarrhea, vomiting and abdominal cramps, and coma may also occur. A national survey by the Drug Abuse Warning Network under commission of the Substance and Mental Health Services Administration, reported that between 1999 and 2001, more than 86% of all life-threatening cases of intoxication recorded by hospital emergency services in the U.S. were associated with the use of MDMA in combination with either alcohol, marijuana, cocaine, or heroin.

The U.S. Department of Justice, Drug Enforcement Administration (DEA ), classifies both illegal and controlled substances under five levels of Schedules, I to V. Most amphetamines are categorized in Schedule I, along with other substances such as LSD, marijuana, peyote, mescaline, heroin, etc. A drug or substance scheduled at level I is thus classified because the drug has a high potential for abuse, has no currently accepted medical use in treatment in the United States, and there is a lack of accepted safety for use of the drug. Therefore, amphetamine parent chemicals scheduled under level I cannot be prescribed by physicians in the United States.

Other amphetamine derivatives such as methamphetamine, phenmetrazine, and methylphenidate are under Schedule II, along with cocaine. Schedule II drugs are described as drugs with a high potential for abuse and physical or psychological dependence, but with currently accepted medical uses in the United States with severe restrictions. Schedule II drugs are tightly regulated and require a written prescription from a licensed physician.

Schedule IIIV amphetamines also require prescription by a physician, but their manufacture and supply are less controlled and the potential for abuse is less. Therapeutic drugs such as some appetite suppressants and some drugs prescribed for attention deficit disorder fall into this category. Some amphetamines are approved by the Food and Drug Administration either as ingredients of pharmaceutical drugs or as a one-salt drug, such as methylphenidate, used in the treatment of narcolepsy, a clinical condition that induces patients to an uncontrollable state of sleepiness that leads to suddenly falling asleep anywhere and at any time.

see also FDA (United States Food and Drug Administration; Illicit drugs; Narcotic; Nervous system overview; Neurotransmitters.

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amphetamine

amphetamine (ămfĕt´əmēn), any one of a group of drugs that are powerful central nervous system stimulants. Amphetamines have stimulating effects opposite to the effects of depressants such as alcohol, narcotics, and barbiturates. They raise the blood pressure by causing the body to release epinephrine, postpone the need for sleep, and can reverse, partially and temporarily, the effects of fatigue. Amphetamines enhance mental alertness and the ability to concentrate, and also cause wakefulness, euphoria, and talkativeness. Benzedrine is the trade name for the drug amphetamine; dextroamphetamine is marketed as Dexedrine. Methamphetamine, a potent stimulant marketed as Desoxyn, is the most rapidly acting amphetamine. They are available by prescription for limited uses; illegal sources include stolen or diverted supplies or clandestine laboratories.

Uses

Prescription amphetamines have been used for short periods of time in weight-control programs to suppress appetite and to treat narcolepsy. They were used as vasoconstrictors in inhalant therapy to shrink nasal mucous membranes in such conditions as nasal allergies and asthma; now such inhalants have been banned because of their toxicity. For unknown reasons, amphetamines have a paradoxically calming effect on some hyperactive children, but the use of these drugs to treat such children has been controversial.

Amphetamine Abuse

Popularly known as bennies, crank, speed, pep pills, wakeups, or uppers, amphetamines are addictive and easily abused: users can become psychologically dependent on the drugs and, developing a tolerance for them, can require increasingly large doses (see drug addiction and drug abuse). When the drugs wear off, a long period of sleep ensues, often followed by hunger and depression, which can lead to further use of amphetamines. Amphetamine addiction has been common among such diverse groups as truck drivers, students, and athletes, who have used the drugs for increased energy, alertness, or endurance. Methamphetamine, made from ephedrine and other chemicals in clandestine laboratories in the the United States or Mexico, experienced a resurgence in use in the United States beginning the mid-1990s, and its abuse also has increased worldwide. Amphetamines are inhaled, taken orally, or injected; as with other injected drugs, needle sharing increases the risk of contracting the AIDS virus. One form of methamphetamine, "ice," is smoked. For law enforcement purposes in the United States, most amphetamines are grouped with such drugs as cocaine and morphine because of the similarity in their effects, medical usefulness, and high potential for abuse.

Side Effects

Amphetamines can produce severe systemic effects, including cardiac irregularities and gastric disturbances. Chronic use often results in insomnia, hyperactivity, irritability, and aggressive behavior. Addiction can result in psychosis or death from overexhaustion or cardiac arrest. Amphetamine-induced psychosis often mimics schizophrenia, with paranoia and hallucinations.

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Amphetamine

AMPHETAMINE

Amphetamine was first synthesized in 1887, but its central nervous system (CNS) stimulant effects were not noted at that time. After rediscovery, in the early 1930s, its use as a respiratory stimulant was established and its properties as a central nervous system stimulant were described. Reports of abuse soon followed. As had occurred with cocaine products when they were first introduced in the 1880s, amphetamine was promoted as being an effective cure for a wide range of ills without any risk of addiction. The medical profession enthusiastically explored the potentials of amphetamine, recommending it as a cure for everything from alcohol hangover and depression to the vomiting of pregnancy and weight reduction. These claims that it was a miracle drug contributed to public interest in the amphetamines, and they rapidly became the stimulant of choicesince they were inexpensive, readily available, and had a long duration of action.

Derivatives of amphetamine, such as Methamphetamine, were soon developed and both oral and intravenous preparations became available for therapeutic uses. Despite early reports of an occasional adverse reaction, enormous quantities were consumed in the 1940s and 1950s, and their liability for abuse was not recognized. During World War II, the amphetamines, including methamphetamine, were widely used as stimulants by the military in the United States, Great Britain, Germany, and Japan, to counteract fatigue, to increase alertness during battle and night watches, to increase endurance, and to elevate mood. It has been estimated that approximately 200 million Benzedrine (amphetamine) tablets were dispensed to the U.S. armed forces during World War II. In fact, much of the research on performance effects of the amphetamines was carried out on enlisted personnel during this period, as the various countries sought ways of maintaining an alert and productive armed force. Although amphetamine was found to increase alertness, little data were collected supporting its ability to enhance performance.

Since 1945, use of the amphetamines and Co-Caine appears to have alternated in popularity, with several stimulant epidemics occurring in the United States. There was a major epidemic of amphetamine and methamphetamine abuse (both oral and intravenous) in Japan right after the war. The epidemic was reported to have involved, at its peak, some half-million users and was related to the release with minimal regulatory controls of huge quantities of surplus amphetamines that had been made for use by the Japanese military. Despite this experience, there were special regulations governing their manufacture, sale, or prescription in the United States until 1964 (Kalant, 1973).

The first major amphetamine epidemic in the United States peaked in the mid-1960s, with approximately 13.5 percent of the university population estimated, in 1969, to have used amphetamines at least once. By 1978, use of the amphetamines had declined substantially, contrasting with the increase of cocaine use by that time. The major amphetamine of concern in the United States in the 1990s is methamphetamine, with pockets of "ice" (smoked methamphetamine) abuse.

Amphetamines are now controlled under Schedule II of the Controlled Substances Act. Substances classified within this schedule are found to have a high potential for abuse as well as currently accepted medical use within the United States. Amphetamine, methamphetamine, cocaine, Methylphenidate, and phenmetrazine are all stimulants included in this schedule.

MEDICAL UTILITY

Amphetamines are frequently prescribed for the treatment of narcolepsy, obesity, and for childhood Attention Deficit Disorder. They are clearly efficacious in the treatment of narcolepsy, one of the first conditions to be successfully treated with these drugs. Although patients with this disorder can require large doses of amphetamine for prolonged periods of time, attacks of sleep can generally be prevented. Interestingly, tolerance does not seem to develop to the therapeutic effects of these drugs, and most patients can be maintained on the same dose for years.

Although the amphetamines have been used extensively in the treatment of obesity, considerable evidence exists for a rapid development of tolerance to the anorectic (appetite loss) effects of this drug, with continued use having little therapeutic effect. These drugs are extremely effective appetite suppressants, but after several weeks of use the dose must be increased to achieve the same appetite-suppressant effect. People remaining on the amphetamines for prolonged periods of time to decrease food intake can reach substantial doses, resulting in toxic side effects (e.g., insomnia, irritability, increased heart rate and blood pressure, and tremulousness). Therefore, these drugs should only be taken for relatively short periods of time (4-6 weeks). In addition, long-term follow-up studies of patients who were prescribed amphetamines for weight loss have not found any advantage in using this medication to maintain weight loss. Data indicate that weight lost under amphetamine maintenance is rapidly gained when amphetamine use is discontinued. In addition to the lack of long-term efficacy, the dependence-producing effects of amphetamines make them a poor choice of maintenance medication for this problem.

The use of amphetamines in the treatment of attention deficit disorders in children, remains extremely controversial. It has been found that the amphetamines have a dramatic effect in reducing restlessness and distractibility as well as lengthening attention span, but there are side effects. These include reports of growth impairment in children, insomnia, and increases in heart rate. Those promoting their use point to their potential benefits and they advocate care in limiting treatment dose and duration. Opponents of their use, while agreeing that they provide some short-term benefits, conclude that these do not outweigh their disadvantages. Amphetamine therapy has also been attempted, but with little success, in the treatment of Parkinson's disease, and both amphetamine and cocaine have been suggested for the treatment of depression, although the evidence to support their efficacy does not meet current standards demanded by the U.S. Food and Drug Administration.

PHARMACOLOGY

The amphetamines act by increasing concentrations of the neurotransmitters Dopamine and Norepinephrine at the neuronal synapse, thereby augmenting release and blocking uptake. It is the augmentation of release that differentiates amphetamines from cocaine, which also blocks uptake of these transmitters. Humans given a single moderate dose of amphetamine generally show an increase in activity and talkativeness, and they report euphoria, a general sense of well-being, and a decrease in both food intake and fatigue. At higher doses repetitive motor activity (i.e., stereotyped behavior) is often seen, and further increases in dose can lead to convulsions, coma, and death. This class of drugs increases heart rate, respiration, diastolic and systolic blood pressure, and high doses can cause cardiac arrhythmias. In addition, the amphetamines have a suppressant effect on both rapid eye movement sleep (REM)the stage of sleep associated with dreamingand total sleep. The half-life of amphetamine is about ten hours, quite long when compared to a stimulant like cocaine, which has a half-life of approximately one hour, or even methamphetamine which has a half-life of about five hours.

The amphetamine molecule has two isomers: the d -(+) and l -(-) isomers. There is marked stereo-selectivity in their biological actions, with the d -isomer (dextroamphetamine) considerably more potent. For example, it is more potent as a locomotor stimulant, in inducing stereotyped behavior patterns, and in eliciting central nervous system excitatory effects. The isomers appear to be equipotent as cardiovascular stimulants. The basic amphetamine molecule has been modified in a number of ways to accentuate various of its actions. For example, in an effort to obtain appetite suppressants with reduced cardiovascular and central nervous system effects, structural modifications yielded such medications as diethylproprion and fenfluramine, while other structural modifications have enhanced the central nervous system stimulant effects and reduced the cardiovascular and anorectic actions, yielding medications such as methylphenidate and phenmetrazine. These substances share, to a greater or lesser degree, the properties of amphetamine.

TOXICITY

A major toxic effect of amphetamine in humans is the development of a schizophrenia-like psychosis after repeated long-term use. The first report of an amphetamine psychosis occurred in 1938, but the condition was considered rare. Administration of amphetamine to normal volunteers with no histories of psychosis (Griffith et al., 1968) resulted in a clear-cut paranoid psychosis in five of the six subjects who received d -amphetamine for one to five days (120-220 mg/day), which cleared when the drug was discontinued. Unless the user continues to take the drug, the psychosis usually clears within a week, although the possibility exists for prolonged symptomology. This amphetamine psychosis has been thought to represent a reasonably accurate model of schizophrenia, including symptoms of persecution, hyperactivity and excitation, visual and auditory hallucinations, and changes in body image. In addition, it has been suggested that there is sensitization to the development of a stimulant psychosisonce an individual has experienced this toxic effect, it is readily reinitiated, sometimes at lower doses and even following long drug-free periods.

Amphetamine abusers taking repeated doses of the drug can develop repetitive behavior patterns which persist for hours at a time. These can take the form of cleaning, the repeated dismantling of small appliances, or the endless picking at wounds on the extremities. Such repetitive stereotyped patterns of behavior are also seen in nonhumans administered repeated doses of amphetamines and other stimulant drugs, and they appear to be related to dopaminergic facilitation. Cessation of amphetamine use after high-dose chronic intake is generally accompanied by lethargy, depression, and abnormal sleep patterns. This pattern of behavior, opposite to the direct effects of amphetamine, does not appear to be a classical abstinence syndrome. The symptoms may be related to the long-term lack of sleep and food intake that accompany chronic stimulant use as well as to the catecholamine depletion that occurs as a result of chronic use.

Animals given unlimited access to amphetamine will self-administer it reliably, alternating days of high intake with days of low intake. They become restless, tremulous, and ataxic, eating and sleeping little. If allowed to continue self-administering the drug, most will take it until they die. Animals maintained on high doses of amphetamines develop tolerance to many of the physically and behaviorally debilitating effects, but they also develop irreversible damage in some parts of the brain, including long-lasting depletion of dopamine. It has been suggested that the prolonged anhedonia seen after long-term human amphetamine use may be related to this, although the evidence for this is not very strong.

BEHAVIORAL EFFECTS

Nonhumans.

As with all Psychomotor Stimulant drugs, at low doses animals are active and alert, showing increases in responding maintained by other reinforcers, but often decreasing food intake. Higher doses produce species-specific repetitive behavior patterns (stereotyped behavior), and further increases in dose are followed, as in humans, by convulsions, hyperthermia, and death. Tolerance (loss of response to a certain dose) develops to many of amphetamine's central effects, and cross-tolerance among the stimulants has been demonstrated in rats. Thus, for example, animals tolerant to the anorectic effects of amphetamine also show tolerance to cocaine's anorectic effects. Although there is tolerance development to many of amphetamine's effects, sensitization develops to amphetamine's effects on locomotor activity. Thus, with repeated administration, doses of amphetamine that initially did not result in hyperactivity or stereotypy can, with repeated use, begin to induce those behaviors when injected daily for several weeks. In addition, there is cross-sensitization to this effect, such that administration of one stimulant can induce sensitization to another one. In contrast to cocaine, however (in which an increased sensitivity to its convulsant effects develops with repeated use), amphetamines have an anticonvulsive effect.

Learned behaviors, typically generated by operant schedules of reinforcement, are generally affected by the amphetamines in a rate-dependent fashion. Thus, behaviors that occur at relatively low rates in the absence of the drug tend to be increased at low-to-moderate doses of amphetamine, while behaviors occurring at relatively high frequencies tend to be suppressed by those doses of amphetamine. In addition, with high doses most behaviors tend to be suppressed. As is seen with other stimulants, such as cocaine, environmental variables and behavioral context can play a role in modulating these effects. For example, behavior under strong stimulus control shows tolerance to repeated amphetamine administration much more rapidly than does behavior under weak stimulus control. In addition, if the amphetamine-induced behavioral disruption has the effect of interfering with reinforcement delivery, tolerance to that effect develops rapidly. Tolerance does not develop to the amphetamine-induced disruptions when reinforcement density is increased or remains the same.

Amphetamines can serve as reinforcers in nonhumans and, as described above, can produce severely toxic consequences when available in an unlimited fashion. However, when available for a few hours a day, animals will take them in a regular fashion, showing little or no tolerance to their reinforcing effects.

Humans.

A substantial number of studies have been carried out evaluating the effects of amphetamines on learning, cognition, and other aspects of performance. The data indicate that under most conditions the amphetamines are not general performance enhancers. When there is improvement in performance associated with amphetamine administration, it can usually be attributed to a reduction in the deterioration of performance due to fatigue or boredom. Attention lapses that impair performance after sleep deprivation appear to be reduced by amphetamine administration; however, as sleep deprivation is prolonged, this effect is reduced. A careful review of the literature in this area (Laties & Weiss, 1981) concluded that improvement is more obvious with complex, as compared with simple, tasks.

In addition, in trained athletes, whose behavior shows little variability, only very small improvements can be seen. Laties and Weiss have argued persuasively, however, that the small changes in performance induced by amphetamines can result in the 1 to 2 percent improvement that may make the difference in a close athletic competition. Although the facilitation in performance after amphetamine does not appear to be substantial, it is sufficient to "spell the difference between a gold medal" and any other. Unfortunately, such data have led athletes to take stimulants prior to athletic events, particularly those in which strenuous activity is required over prolonged periods (e.g., bicycle racing), leading to hyperthermia, collapse, and even death in some cases.

The mood-elevating effects of the amphetamines are generally believed to be related to their abuse. Their use is accompanied by reports of increased self-confidence, elation, frequently euphoria, friendliness, and positive mood. When amphetamine is administered repeatedly, tolerance develops rapidly to many of its subjective effects (such that the same dose no longer exerts much of an effect). This means that the user must take increasingly larger amounts of amphetamine to achieve the same effect. As with nonhuman research subjects, there is however, little or no evidence for the development of tolerance to amphetamine's reinforcing effects.

Experienced stimulant users, given a variety of stimulant drugs, often cannot differentiate among cocaine, amphetamine, methamphetamine, and methlyphenidateall of which appear to have similar profiles of action. Since these drugs have different durations of action, however, it becomes easier to make this differentiation over time.

ABUSE

In the United States in the 1950s, nonmedical amphetamine use was prevalent among college students, athletes, truck drivers, and housewives. The drug was widely publicized by the media when very little evidence of amphetamine toxicity was available. Pills were the first form to be widely abused. Use of the drug expanded as production of amphetamine and methamphetamine increased significantly, and abusers began to inject it. An extensive black market in amphetamines developed, and it has been estimated that 50 to 90 percent of the quantity commercially produced was diverted into illicit channels. In the 1970s, manufacture of amphetamines was substantially curtailed, amphetamines were placed in Schedule II of the Controlled Substances Act, and abuse of these substances was substantially reduced. Perhaps only by coincidence, as amphetamine use declined, cocaine use increased.

The amphetamines, as with other stimulants, are generally abused in multiple-dose cycles (i.e., binges), in which people take the drug repeatedly for some period of time, followed by a period in which they take no drug. Amphetamines are often taken every three or four hours for periods as long as three or four days, and dosage can escalate dramatically as tolerance develops. Like cocaine binges, these amphetamine-taking occasions are followed by a "crash" period in which the user sleeps, eats, and does not use the drug. Abrupt cessation from amphetamine use is usually accompanied by depression. Mood generally returns to normal within a week, although craving for the drug can last for months.

There is little evidence for the development of physical dependence to the amphetamines. Although some experts view the "crash" (with lethargy, depression, exhaustion, and increased appetite) that can follow a few days of moderate-to-high dose use as meeting the criteria for a withdrawal syndrome, others believe that the symptoms can also be related to the effects of chronic stimulant use. When using stimulants people do not eat or sleep very much and, as well, catecholamine depletion may well be contributing to these behavioral changes.

TREATMENT

As of the mid-1990s, little information is available about the treatment of amphetamine abusers, and no reports of successful pharmacological interventions exist in the treatment literature. As with cocaine abuse, the most promising nonpharmacological approaches include behavioral therapy, Relapse Prevention, rehabilitation (e.g., vocational, educational, and social-skills training), and supportive psychotherapy. Unlike cocaine, however, minimal clinical trials with potential treatment medications for amphetamine abuse have been carried out. The few that have been attempted report no success in reducing a return to amphetamine use.

(See also: Amphetamine Epidemics ; Pharmacokinetics ; Treatment )

BIBLIOGRAPHY

Angrist, B., & Sudilovsky, A. (1978). Central nervous system stimulants: Historical aspects and clinical effects. In L. L. Iversen, S. D. Iverson, & S. H. Snyder (Eds.), Handbook of psychopharmacology. New York: Plenum.

Griffith, J. D., et al. (1970). E. Costa and S. Garattini (Eds.), Amphetamines and related compounds. New York: Raven Press.

Grilly, D. M. (1989). Drugs and human behavior. Needham, MA: Allyn & Bacon.

Kalant, O. J. (1973). The amphetamines: Toxicity and addiction. Springfield, IL: Charles C. Thomas.

Laties, V.G., & Weiss, B. (1981). Federation proceedings, 40, 2689-2692.

Marian W. Fischman

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amphetamines

amphetamines (am-fet-ăminz) pl. n. a group of sympathomimetic drugs that have a marked stimulant action on the central nervous system. Dexamfetamine (dexamphetamine; Dexedrine), administered by mouth, is used in the treatment of narcolepsy and attention-deficit/hyperactivity disorder. Tolerance to amphetamines develops rapidly, and prolonged use may lead to dependence.

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amphetamine

amphetamine Drug that stimulates the central nervous system. These drugs (also known as ‘pep pills’ or ‘speed’) can lead to drug abuse and dependence. They can induce a temporary sense of well-being, often followed by fatigue and depression. An example is the synthetic drug methamphetamine, a methyl derivative of amphetamine. See also addiction

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"amphetamine." World Encyclopedia. . Encyclopedia.com. (April 25, 2017). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/amphetamine

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amphetamine

amphetamine A drug, 1-phenyl-2-aminopropane (or a derivative of this compound), that stimulates the central nervous system by causing the release of the transmitters noradrenaline and dopamine from nerve endings. It inhibits sleep, suppresses the appetite, and has variable effects on mood; prolonged use can lead to addiction.

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"amphetamine." A Dictionary of Biology. . Encyclopedia.com. 25 Apr. 2017 <http://www.encyclopedia.com>.

"amphetamine." A Dictionary of Biology. . Encyclopedia.com. (April 25, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amphetamine-0

"amphetamine." A Dictionary of Biology. . Retrieved April 25, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amphetamine-0

amphetamine

am·phet·a·mine / amˈfetəˌmēn; -min/ • n. a synthetic, addictive, mood-altering drug, C6H5CH2CH(CH3)NH2, used illegally as a stimulant and as a prescription drug to treat ADD and narcolepsy.

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"amphetamine." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 25 Apr. 2017 <http://www.encyclopedia.com>.

"amphetamine." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (April 25, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/amphetamine-0

"amphetamine." The Oxford Pocket Dictionary of Current English. . Retrieved April 25, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/amphetamine-0

amphetamine

amphetamine Also known as benzidrine. A chemical at one time used as an appetite suppressant; addictive, and a common drug of abuse (‘speed’), its use is strictly controlled by law.

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"amphetamine." A Dictionary of Food and Nutrition. . Encyclopedia.com. 25 Apr. 2017 <http://www.encyclopedia.com>.

"amphetamine." A Dictionary of Food and Nutrition. . Encyclopedia.com. (April 25, 2017). http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/amphetamine

"amphetamine." A Dictionary of Food and Nutrition. . Retrieved April 25, 2017 from Encyclopedia.com: http://www.encyclopedia.com/education/dictionaries-thesauruses-pictures-and-press-releases/amphetamine

amphetamine

amphetamine 1-phenyl-2-aminopro-pane, a drug that stimulates the central nervous system and prevents sleep.

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"amphetamine." A Dictionary of Zoology. . Encyclopedia.com. 25 Apr. 2017 <http://www.encyclopedia.com>.

"amphetamine." A Dictionary of Zoology. . Encyclopedia.com. (April 25, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amphetamine

"amphetamine." A Dictionary of Zoology. . Retrieved April 25, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/amphetamine

amphetamine

amphetamine •gamine • bromine • thiamine •dopamine • amphetamine • histamine •quinine • strychnine • mezzanine •spalpeen • Philippine • lycopene •gangrene • terrene • silkscreen •windscreen • citrine • Dexedrine •putting green • Benzedrine •Irene, polystyrene •widescreen • sight screen •chlorine, chorine, Doreen, Maureen, Noreen, taurine •smokescreen • rood screen •sunscreen • fluorine • helleborine •Gadarene • Hippocrene •glycerine (US glycerin), nitroglycerine (US nitroglycerin) •nectarine • wintergreen • Methedrine •evergreen • wolverine • vaccine •glassine • Essene • Rexine • piscine •epicene • glycine • pyroxene •Palaeocene (US Paleocene) •Pliocene • Miocene • Holocene •damascene • kerosene • Plasticine •Pleistocene

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"amphetamine." Oxford Dictionary of Rhymes. . Encyclopedia.com. 25 Apr. 2017 <http://www.encyclopedia.com>.

"amphetamine." Oxford Dictionary of Rhymes. . Encyclopedia.com. (April 25, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/amphetamine

"amphetamine." Oxford Dictionary of Rhymes. . Retrieved April 25, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/amphetamine