Amphetamines

Amphetamines are central nervous system stimulants used medically to treat narcolepsy and attention deficit hyperactivity disorder (ADHD) that are also used illegally for recreational and performance-enhancing purposes. The term amphetamine refers to a class of drugs that includes amphetamine itself as well as the compounds dextroamphetamine (known commercially as Dexedrine®), methamphetamine, and MDMA. Methamphetamine in its various forms is commonly referred to as “speed,” “crystal meth,” “ice,” or “Tina,” while MDMA is frequently called “ecstasy,” “E,” or “X.” The illicit usage of all amphetamines has emerged in recent years as an important public health problem.

In the United States, amphetamine, dextroamphetamine, and methamphetamine are classified as Drug Enforcement Administration (DEA) Schedule II drugs, which means that they have high potential for abuse, but can be made available in some medically necessary circumstances. MDMA is a Schedule I drug, implying that it also has a high potential for abuse, but has no currently accepted medical use.

The sensation acquired after using any of the various amphetamines varies with the route of administration. In general, injection produces the most immediate effects. Inhalation by smoking produces a slower “high,” and the ingestion of pills provides the most delayed physiological changes. A “rush” of euphoria, an intensely pleasurable feeling attained soon after taking an amphetamine, is unique to injection and inhalation.

Pharmacologically, amphetamines act by altering the transmission of central nervous system monoamine neurotransmitters, particularly norepinephrine, dopamine, and serotonin. The various amphetamines exert slightly different psychological changes, but in general, all act as potent stimulants, causing euphoria, enhancing alertness, improving attention, and increasing libido if taken in substantial doses. The abuse [Page 124]of amphetamines for recreational and performance-enhancing purposes is related to these effects.

Physiologically, amphetamines cause increased heart rate, blood pressure, respiratory rate, and temperature, and, in excess, can lead to cardiac arrhythmia, hyperthermia, stomach cramping, nystagmus (rapid beating) of the eyes, tremors, stereotyped behaviors, anxiety, aggression, paranoia, and insomnia. Cardiac abnormalities and stroke occur rarely but are often fatal. “Coming down” off amphetamines causes the opposite effects, most notably fatigue, difficulty concentrating, and mood depression.