Amphetamines (World of Forensic Science)

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 6020 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 4 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 III 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.