This is the 2007 version. Click here for the 2017 chapter 03 table of contents.

Different Categories of Drugs

Depressants are drugs that lower the overall level of activity in the nervous system. Among the chemically distinct families of depressant drugs are sedatives, hypnotics, and alcohol. All are capable of producing relaxation or sluggish and lethargic behavior. In large doses all can produce coma or death. Sedatives include drugs like PCP (phencyclidine), a drug commonly abused in the 1970s and 1980s, and barbiturates, used in sleeping potions and pills from the 1800s through the first half of the 20th Century. Depressants are often potentiated (made much more powerful) by combination with alcohol.

What are depressants?

Hypnotics include muscle-relaxants like methaqualone (quaaludes). Like PCP, its manufacture requires sophisticated processes, so it was "taken off the streets" by limiting the number of factories authorized to produce it.

What are effects of stimulants?

Stimulants are drugs that increase overall activity and excitability in the nervous system. Commonly known stimulants are caffeine, amphetamines ("speed"), and cocaine. Stimulants increase alertness and activity. In large amounts, they cause nervousness, shaking movements or jitters, insomnia, and irregular heartbeats. Sometimes they cause anxiety or panic states accompanied by hyperventilation and lightheadedness.

What are opiates? Which types of drugs are properly called "narcotics" and which are not?

Opiates are drugs derived from the opium poppy or synthetic drugs similar to natural opiates in chemical structure and action. Opiates include heroin, morphine, and codeine, as well as the endorphins-natural pain-killing substances secreted by the body. To pharmacologists, opiates are the only drugs properly termed narcotics. Cocaine, marijuana, sedatives, and LSD are not narcotics, unless the term is used loosely to refer to all illegal drugs.

Why is marijuana in a category by itself?

Marijuana (cannabis) is in a category by itself, because it does not resemble other drugs either in chemical structure or effect. The active ingredient in marijuana is delta-4-tetrahydrocannabinol or THC. Marijuana achieves its effect by altering levels of a particular type of transmitter-anandamide-that is not affected by other drugs. Anandamide receptors are very common in the human nervous system, so the transmitter must be involved in important brain processes, but its normal function is not yet clear. Hashish is a form of concentrated cannabis resin.

What are common psychedelics, and what are their effects?

Hallucinogens or psychedelic drugs include LSD (lysergic acid diethylamide or "acid"), mescaline (the active ingredient in peyote buttons), and psilocybin (the active ingredient in psychoactive mushrooms). They cause a dreamlike state ("trip") with dramatic alterations of thought and emotion. The major psychedelics are all chemically related. Their hallucinogenic effects are thought to be caused by reduction in a variety of the neurotransmitter serotonin (see Chapter 2).

The internet provides many web sites about drugs and their effects, ranging from sites focusing on prevention of substance abuse (such as <> to sites where users share experiences and cautions about drugs ranging from caffeine to hallucinogens <>.

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